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Oberlin Astronomy
CCD Manual
Contents
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Introduction
It was soon discovered after the advent of film that the human eye was not the best tool for astronomy. Photographic plates, able to capture minutes or hours of photons, could collect light from stars and gas far fainter than the eye could ever see. Astrophotography has since become the backbone of some of the greatest scientific discoveries of the past century.
The digital age brought about a new tool that improved astronomy as much as film did to the eye: the CCD camera. Standing for Charged Coupled Device, this instrument has a silicon chip that takes advantage of the photoelectric effect to create digital images. The sensitivity and precision of such chips far surpasses the best film plates.
That said, CCD imaging can be a difficult and sometimes trying process. Unlike using a simple point-and-shoot digital camera in daylight, Astrophotography typically requires exposures that last many minutes or hours. In order to avoid streaking, the camera must keep all of the stars and other objects exactly in the same position for the entire exposure. This is not easy considering that the earth rotates one quarter of a degree every minute and no telescope mount is perfect. Other obstacles include focusing, changing atmospheric conditions and various technical mishaps. This manual is designed to glide its users through these difficulties with as much speed and ease as possible.
The manual is full of pictures and diagrams. Besides the "main idea" pictures, there are many links after technical terms and confusing descriptions that may be clicked on for further clarification. They are followed by this camera icon:
.
If you are reading this off a dim computer screen, you may want to
increase the text size in your browser's View menu.| Contents | Previous | Next |
Requirements
This manual is
designed for all students, faculty, and staff with varying levels of
experience.
However, there are a few basic requirements needed before one can begin
this process.
- Knowledge of a few constellations: This is a necessity. There is a useful aid in finding celestial objects, but it requires alignment with a star. Simply knowing Orion will do, as long as it is up. Sky and Telescope magazine is a good place to start learning the skies. The planetarium has copies and you may buy it in the college bookstore.
- Patience: The manual is designed to make imaging as easy as possible, but a few tries will probably be needed before producing satisfactory results. It is recommended that one allot at least three hours to find some objects and take exposures.
- Keys and passwords: For access to the camera and equipment, see Lee Lumpkin, Mike Williams, Dan Stinebring or Chris Martin. They also will have the computer passwords on a CCD Imaging Information Sheet.
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Getting Started
Turn on the fan
The dome tends to heat up during the day. The temperature differential
with the outside air can significantly impair seeing conditions. For
this reason, there is a fan in the lower room that will help blow
air upstairs and out the dome. Turn it on by plugging it in about 5
hours before you begin work.
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Refractor or
Reflector?
There are two kinds of setups for CCD work. The refractor 
setup
is much easier, but it has a few drawbacks. The images tend to be very
wide. That is, lots of the sky is captured with each exposure. This
makes it easier to guide, find objects, and make nice pictures, but
small star clusters, nebulas, and galaxies barely fill up a tiny
portion of the field of view. Only huge objects like the Andromeda
galaxy are expansive enough for this setup. The other drawback is that
scientific data and photometry tend to be very imprecise. Beginners and
those looking for easy pretty pictures should use the refractor.
The 14" Schmidt-Cassegrain Reflector
is far more difficult use. The area covered by the sky tends to
be very small, making it harder to find celestial objects. Each step of
the process takes longer and has a greater chance of failure. However,
this setup will provide good close-ups, high detail, and precise
photometric data. Small objects can fill the entire CCD chip.
setup
is much easier, but it has a few drawbacks. The images tend to be very
wide. That is, lots of the sky is captured with each exposure. This
makes it easier to guide, find objects, and make nice pictures, but
small star clusters, nebulas, and galaxies barely fill up a tiny
portion of the field of view. Only huge objects like the Andromeda
galaxy are expansive enough for this setup. The other drawback is that
scientific data and photometry tend to be very imprecise. Beginners and
those looking for easy pretty pictures should use the refractor.The 14" Schmidt-Cassegrain Reflector
is far more difficult use. The area covered by the sky tends to
be very small, making it harder to find celestial objects. Each step of
the process takes longer and has a greater chance of failure. However,
this setup will provide good close-ups, high detail, and precise
photometric data. Small objects can fill the entire CCD chip.| Contents | Previous | Next |
Make sure you have all the equipment you'll need
1. A red flashlight (any
kind will do)
2. CCD Camera
3. Power cable for camera
4. USB cable
5. Robofocuser box with 9-pin ribbon cable, serial cable, and power cable
(reflector setup only)
6. Relay box with camera cable and drive controller cable
7. Eyepiece illuminator,
usually stored in the eyepiece cabinet
(reflector only)
2. CCD Camera
3. Power cable for camera
4. USB cable
5. Robofocuser box with 9-pin ribbon cable, serial cable, and power cable
(reflector setup only)6. Relay box with camera cable and drive controller cable
7. Eyepiece illuminator
,
usually stored in the eyepiece cabinet 
(reflector only)
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Opening Up
1. Open all possible
windows in the room
below the telescope. For the best viewing, the dome,
telescope, inside and outside air should be in thermal equilibrium. The
northeast window must be held open with a block so it does not bang
around.
2. Turn off the fan
by unplugging it. The vibrations of the fan
can disturb images.
3. Open the dome shutters. The loud squeaks are normal.
4. Lift the dust cover off the Schmidt-Cassegrain telescope.
5. Store the ladder on the outside perimeter of the dome. Open the black chest, take out the cylindrical dew shield and put in the dust cover.
5. Remove the telescope lid
and replace it with the dew shield.
It is
best to slide the top of the dew shield on first. Store the lid in the
chest with the dust cover. If the telescope does not stay upright, you
may lock the declination and
right ascension knobs by
turning them clockwise.
NOTE: Even if you use the refractor, the dew shield is necessary for balancing purposes.
6. Remove the dust cap from the refractor finderscope.
7. Wake up the Windows computer (on the right) by pressing any key. (If it is off, you will need to start it up and use the password you were given). Find a red screen
in the cabinet and place it on the computer
so it does not destroy your night vision later.
2. Turn off the fan
by unplugging it. The vibrations of the fan
can disturb images.3. Open the dome shutters. The loud squeaks are normal.
4. Lift the dust cover off the Schmidt-Cassegrain telescope.
5. Store the ladder on the outside perimeter of the dome. Open the black chest, take out the cylindrical dew shield and put in the dust cover.
5. Remove the telescope lid
and replace it with the dew shield.
It is
best to slide the top of the dew shield on first. Store the lid in the
chest with the dust cover. If the telescope does not stay upright, you
may lock the declination 
and
right ascension knobs 
by
turning them clockwise.NOTE: Even if you use the refractor, the dew shield is necessary for balancing purposes.
6. Remove the dust cap from the refractor finderscope.
7. Wake up the Windows computer (on the right) by pressing any key. (If it is off, you will need to start it up and use the password you were given). Find a red screen
in the cabinet and place it on the computer
so it does not destroy your night vision later. | Contents | Previous | Next |
Initial Setup
The following setup should
already be done, but you may wish to check it anyway. Otherwise, skip
to the next section.
1. Make sure that the drive motors are plugged in. There should be a Losmandy Drive System box
located on the pier. The RA should be plugged
into the lower motor
and the Declination should be plugged into the
upper motor
(upper and lower are referenced to when the
telescope is upright and North). The power chord
should be connected to the Anderson Power supply hub on the side of the
pier .
There should also be a hand paddle
plugged into the CCD/HC
port .
2. The Van Slyke focuser
should already be in the telescope. If not, thread it on and lock it.
NOTE: Refractor setup is better balanced with this focuser on.
3. (Refractor Only) Make sure the Robofocus motor gear is engaged in the focuser.
If
not, the focus settings will have to be re-calibrated.
1. Make sure that the drive motors are plugged in. There should be a Losmandy Drive System box
located on the pier. The RA should be plugged
into the lower motor 
and the Declination should be plugged into the
upper motor
(upper and lower are referenced to when the
telescope is upright and North). The power chord
should be connected to the Anderson Power supply hub on the side of the
pier 
.
There should also be a hand paddle 
plugged into the CCD/HC
port 
.2. The Van Slyke focuser
should already be in the telescope. If not, thread it on and lock it.NOTE: Refractor setup is better balanced with this focuser on.
3. (Refractor Only) Make sure the Robofocus motor gear is engaged in the focuser
.
If
not, the focus settings will have to be re-calibrated.4. Make sure there is an
extension tube on the refractor.
5. Make sure that the refractor finderscope has the 9mm eyepiece with a hole for the red illuminator.
5. Make sure that the refractor finderscope has the 9mm eyepiece with a hole for the red illuminator.
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Attaching the Camera
Putting it on the Scope (Refractor setup only. Click to skip to Reflector setup)
1. Lock down the
declination and
right ascension knobs .
2. Remove the 9mm eyepiece
and 2" adapter
from the refractor
by loosening the two set screws .
Set them on a level surface.
and
right ascension knobs .2. Remove the 9mm eyepiece
and 2" adapter
from the refractor
by loosening the two set screws 
.
Set them on a level surface.3. Remove the camera's lens
cap .
Carefully put the
camera in the
back of the refractor so the ports all face downward. You may
need to loosen the set screws
to get it in.
Push the camera flush against
the tube and tighten the set screws .
.
Carefully put the
camera in the
back of the refractor so the ports all face downward. You may
need to loosen the set screws
to get it in.
Push the camera flush against
the tube and tighten the set screws .4. Loosen the focus lock
knob and
adjust the focus knob
until the CCD
line is approximately at the mark. Tighten down the focus lock knob
again. Check to make sure there is no wobble in the CCD.
and
adjust the focus knob
until the CCD
line is approximately at the mark. Tighten down the focus lock knob
again. Check to make sure there is no wobble in the CCD.5. Tie the
camera's strap to the left D ring, but leave some
slack for focusing.
Putting it on the Scope (Reflector setup only. Click to skip)
1. Lock down the
declination and
right ascension knobs .
2. Remove the eyepiece
from the focuser by loosening the nylon set screws .
Set it on
a level surface.
3. Remove the camera's lens cap
and carefully put the
camera in the
back of the focuser. You may need to loosen the lock screws
first. The ports should all be oriented downward .
Push it flush against
the tube and tighten the lock screws.
4. Tie the camera's strap to the left D ring, but leave some slack for focusing.
5. Screw in the finderscope illuminator.
and
right ascension knobs .2. Remove the eyepiece
from the focuser by loosening the nylon set screws 
.
Set it on
a level surface.3. Remove the camera's lens cap
and carefully put the
camera in the
back of the focuser. You may need to loosen the lock screws
first. The ports should all be oriented downward 
.
Push it flush against
the tube and tighten the lock screws.4. Tie the camera's strap to the left D ring, but leave some slack for focusing.
5. Screw in the finderscope illuminator.
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Making the Connections
1. Camera connections
a. Plug the USB cable into one the Windows computer's top left USB port.
Run the wire safely across the floor and
up to
the camera's USB port
b. Plug the autoguider controls in with the relay box.
Looking down on the box so that it reads “SBIG
astronomical
images,” the right side goes to the camera
(AO/CFW/SCOPE)
and the left side goes to the digital drive system (HC/CCD) ,
but that
should have a hand paddle already plugged in .
Leave the hand paddle for
now and be ready to switch these later.
c. Find the surge protector at the base of the pier.
Make sure it is on.
If the red LED doesn't light, you may
need to plug in the extension chord in the room below .
Plug one end of
the power box into the surge protector
and the other end into the
camera's power port .
Place the power box
on the pier so it wedges between the mount and an allen screw .
This is necessary because the power chord is slightly short and you can
end up dragging the power box around.
d. Turn the camera on by flipping the (I/O) switch on the power box.
2. Turn on the Anderson supply hub by flipping the I/O switch on the transformer box.
3. Robofocuser Box (Reflector setup only. Click to skip)
a. Connect the PC cable to the computer's S4 serial port
b. Connect the 9-pin ribbon cable to the ROBOFOCUS motor.
c. Connect the power to the red and black Anderson Power Poles hub.
d. Turn the Robofocuser box on. It should have a red LED indicator light.
4. IMPORTANT! First, ground your hand against the pier. Turn on the Losmandy digital drive system.
Starting
the Software and Cooling
a. Plug the USB cable into one the Windows computer's top left USB port
.
Run the wire safely across the floor and
up to
the camera's USB port 
b. Plug the autoguider controls in with the relay box
.
Looking down on the box so that it reads “SBIG
astronomical
images,” the right side goes to the camera
(AO/CFW/SCOPE) 
and the left side goes to the digital drive system (HC/CCD) ,
but that
should have a hand paddle already plugged in .
Leave the hand paddle for
now and be ready to switch these later.c. Find the surge protector at the base of the pier
.
Make sure it is on.
If the red LED doesn't light, you may
need to plug in the extension chord in the room below 
.
Plug one end of
the power box into the surge protector
and the other end into the
camera's power port 
.
Place the power box 
on the pier so it wedges between the mount and an allen screw 
.
This is necessary because the power chord is slightly short and you can
end up dragging the power box around.d. Turn the camera on by flipping the (I/O) switch on the power box
.NOTE: This image is the
reflector setup, but the refractor setup has the same connections.
2. Turn on the Anderson supply hub by flipping the I/O switch on the transformer box.
3. Robofocuser Box (Reflector setup only. Click to skip)
a. Connect the PC cable to the computer's S4 serial port
b. Connect the 9-pin ribbon cable to the ROBOFOCUS motor
.c. Connect the power to the red and black Anderson Power Poles hub
.d. Turn the Robofocuser box on. It should have a red LED indicator light.
4. IMPORTANT! First, ground your hand against the pier. Turn on the Losmandy digital drive system.
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Starting
the Software and Cooling
1. Double click on the
CCDsoft shortcut on the desktop.
2. Once it is open, go to the Camera menu and select "Setup..." This will open a new window.
3. Click on the Connect button to connect to the camera. If it does not connect, try unplugging the USB cable and plugging it back in. Once it has connected, you will see the status of both the Imager and Autoguider at the bottom of the window.
4. Click on the "Temperature..." button. Set the target temperature to about 20-30 degrees below the temperature indicated in the bottom of the Camera Control window. Turn the cooling on and click OK.
will stay on, but you may cover it up so that the light only goes
down .
A red flashlight should be used for the rest session so that you
keep your night vision. If you need to see better, try using the dim
red lights first .
2. Look for a 3rd magnitude star or brighter. For reference, all but one of the main seven Big Dipper stars are far brighter than 3rd magnitude. All of the seven main stars in Orion are also far brighter than 3rd magnitude.
3. Use the hand controller to rotate the dome and center it on the bright star you have chosen. The dome can squeak, bang and pop while moving, but any excessively loud sounds indicate a failure. In case of a failure, see the emergency contact info on the CCD Imaging Information Sheet.
4. Make sure the right ascension
and declination
knobs are loose. Point the telescope at
the star using the D rings .
If it appears to be imbalanced, see section on balance.
Turn on the Telrad finder
by flipping the right dimmer
switch
and sight the red circles
through it.
Put the star directly inside the circles. Now, lock down the right
ascension
and declination
knobs.
5. (Reflector setup only. Click here to skip) Turn on the finderscope's illuminated reticle.
Look through the finderscope's eyepiece .
There should be a
bright star near the center. If it is out of focus, loosen the focus
lock knob ,
adjust the focus
and tighten the focus lock knob
so there is no wobble. Use the hand paddle
to center the star in the crosshairs.
The hand controller's movements can be very slow. If you want to speed
them up, hold
the button in the direction you wish to move and then press the
opposite side at the same time (high speed).
5. If the Camera Control window has been closed, re-open it by selecting "Setup..." from the Camera menu. Click on the Take Image tab and check that the settings match the following picture.
6. You are now ready to take your first image. Switch to the Focus Tools tab. Change the settings so they look like the following:
2. Once it is open, go to the Camera menu and select "Setup..." This will open a new window.
3. Click on the Connect button to connect to the camera. If it does not connect, try unplugging the USB cable and plugging it back in. Once it has connected, you will see the status of both the Imager and Autoguider at the bottom of the window
.4. Click on the "Temperature..." button. Set the target temperature to about 20-30 degrees below the temperature indicated in the bottom of the Camera Control window. Turn the cooling on and click OK.
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Aligning the Scopes
1. At this point, all bright lights should be turned off. One staircase light
will stay on, but you may cover it up so that the light only goes
down 
.
A red flashlight should be used for the rest session so that you
keep your night vision. If you need to see better, try using the dim
red lights first 
.2. Look for a 3rd magnitude star or brighter. For reference, all but one of the main seven Big Dipper stars are far brighter than 3rd magnitude. All of the seven main stars in Orion are also far brighter than 3rd magnitude.
3. Use the hand controller to rotate the dome and center it on the bright star you have chosen. The dome can squeak, bang and pop while moving, but any excessively loud sounds indicate a failure. In case of a failure, see the emergency contact info on the CCD Imaging Information Sheet.
4. Make sure the right ascension
and declination
knobs are loose. Point the telescope at
the star using the D rings 
.
If it appears to be imbalanced, see section on balance.
Turn on the Telrad finder 
by flipping the right dimmer
switch
and sight the red circles
through it.
Put the star directly inside the circles. Now, lock down the right
ascension
and declination
knobs.5. (Reflector setup only. Click here to skip) Turn on the finderscope's illuminated reticle
.
Look through the finderscope's eyepiece .
There should be a
bright star near the center. If it is out of focus, loosen the focus
lock knob ,
adjust the focus
and tighten the focus lock knob
so there is no wobble. Use the hand paddle
to center the star in the crosshairs.
The hand controller's movements can be very slow. If you want to speed
them up, hold
the button in the direction you wish to move and then press the
opposite side at the same time (high speed).5. If the Camera Control window has been closed, re-open it by selecting "Setup..." from the Camera menu. Click on the Take Image tab and check that the settings match the following picture.
6. You are now ready to take your first image. Switch to the Focus Tools tab. Change the settings so they look like the following:
7. Click on Take Image. The
Status bar below this window will show the exposure and download taking
place. After the focus shot has been loaded, it will repeat the process
so that it continually updates the view.
8. If all is well, you will see a large star somewhere in the focus frame. If not, see appendix on serious misalignment. If it appears significantly larger
than the one below, you need to adjust the
focus (refractor
focusing. reflector
focusing).
8. If all is well, you will see a large star somewhere in the focus frame. If not, see appendix on serious misalignment. If it appears significantly larger
than the one below, you need to adjust the
focus (refractor
focusing. reflector
focusing).8. Center the star in the
window using the hand paddle. The following is a directional guide, but
it depends
on the position of your star with respect to the meridian. Remember
to
switch to the correct RA and DEC settings. You may have
to hold an arrow for a few
seconds to see a change, but don't use high speed with the reflector
setup.
9. When the star is approximately in the center, align the Telrad.
Use the
three black knobs to re-center the red target.
10. (Reflector Only. Click here to skip) Look through the finderscope eyepiece.
If the star is off-center, the finderscope must be re-aligned. Use the
three nearest knobs to change the direction. Adjust them until
the
star is directly in the center .
 |
 |
 |
 |
9. When the star is approximately in the center, align the Telrad
.
Use the
three black knobs to re-center the red target.10. (Reflector Only. Click here to skip) Look through the finderscope eyepiece
.
If the star is off-center, the finderscope must be re-aligned. Use the
three nearest knobs to change the direction. Adjust them until
the
star is directly in the center .| Contents | Previous | Next |
Focusing
Focusing with the Refractor (Click here to skip to Reflector)
1. Point the telescope at
any bright star.
2. Use the Focus Tools tab again
and click the Take Image button. The camera should take repeated 1
second exposures.
3. Loosen the focus lock knob.
Adjust the focus knob
until
the stars are the smallest size possible. As better focus is
approached, dimmer stars can come into view .
4. Click in the window and draw a box around some of the fainter stars. This will set the sub-frame for future exposures.
In order to use
the sub-frame, press the Abort button and then click Take Image again.
You should now see a sub-frame and the downloading should take much
less time.
2. Use the Focus Tools tab again
and click the Take Image button. The camera should take repeated 1
second exposures.3. Loosen the focus lock knob
.
Adjust the focus knob
until
the stars are the smallest size possible. As better focus is
approached, dimmer stars can come into view 
.4. Click in the window and draw a box around some of the fainter stars. This will set the sub-frame for future exposures
.
In order to use
the sub-frame, press the Abort button and then click Take Image again.
You should now see a sub-frame and the downloading should take much
less time.5. Press Control-2 to zoom
in. This will
make focusing easier. (Control 2,3, and 4 zoom in while Alt 2,3,4 zoom
out. Control-1 = Alt-1 = normal size.)
6. Fine-tune the focus with
the focus
knob (until the stars are as small as possible). Lock down the focus
with the lock knob .
7. Check to make sure there is no wobble in the refractor. Nothing should be loose.
.7. Check to make sure there is no wobble in the refractor. Nothing should be loose.
Focusing with the Reflector (Click here to skip)
1. Point the telescope at a star slightly less bright than the one you
just aligned with. First use the Telrad
to roughly center the star. Next, use the finderscope and hand
paddle
to put the camera where it needs to be .
In other words go back to steps 3-5 in Aligning the Scopes.
Click the Take Image button to make sure it is
inside the frame. If the star looks unreasonably large or has a dark
hole in the center ,
see appendix on
focusing.
2. Open the FocusMax program on the desktop. It will automatically open several windows, which you may want to re-arrange.
5. You now need to set the v-curve options. As circled above, set the Half Width to 6,000 steps. Set the Step Incr. to -500. The center position should be the current focuser position. You can obtain the current focuser position in the Robofocus control program next to A/R.
to roughly center the star. Next, use the finderscope and hand
paddle
to put the camera where it needs to be .
In other words go back to steps 3-5 in Aligning the Scopes.
Click the Take Image button to make sure it is
inside the frame. If the star looks unreasonably large or has a dark
hole in the center 
,
see appendix on
focusing.2. Open the FocusMax program on the desktop. It will automatically open several windows, which you may want to re-arrange.
3. FocusMax should have
opened the Robofocus control program and it should be visible in
the Task Bar. You can see the absolute position by clicking the A/R
button. To focus, use the In and Out buttons to move the stepper motor.
500 steps is a good size.
4. Once the star is roughly
focused, switch to the FocusMax program and click on the V Curve
button to set up a V-curve. The parameters in the window will probably
be different than yours.
5. You now need to set the v-curve options. As circled above, set the Half Width to 6,000 steps. Set the Step Incr. to -500. The center position should be the current focuser position. You can obtain the current focuser position in the Robofocus control program next to A/R
.6. Click Run to begin the V
curve. You can watch as each data point is taken. Also, the Log
button
will give you an idea of what the program is doing.
7. When the v-curve is finished running, you will see a Profile window. This contains the results of this v-curve as well as previous ones. Ideally, you should see a L Slope and R Slope that vary by no more than 3%. If they differ considerably, you may want to re-run the v-curve.
will give you an idea of what the program is doing.7. When the v-curve is finished running, you will see a Profile window. This contains the results of this v-curve as well as previous ones. Ideally, you should see a L Slope and R Slope that vary by no more than 3%. If they differ considerably, you may want to re-run the v-curve.
8. Choose the data sets
that you want to use by clicking the Y/N box. Old ones should be used
only if the setup has not changed since the last person used the
camera. Obsolete data can be deleted by clicking the box left of the
Y/N and clicking the Delete Records button.
9. Now that a V-curve has been taken, you are ready to focus. Use the FocusMax Setup tab to set the parameters. Click the arrow to calculate a good start position for a half-width of 20.
9. Now that a V-curve has been taken, you are ready to focus. Use the FocusMax Setup tab to set the parameters. Click the arrow to calculate a good start position for a half-width of 20.
10. Switch back to the
Focus tab and
click Focus to begin focusing. If you need
to focus again, you can simply click the focus button.
and
click Focus to begin focusing. If you need
to focus again, you can simply click the focus button.| Contents | Previous | Next |
Flat-Fielding
Flat-fielding is the process where you compensate for the telescope system's optical imperfections. It is absolutely necessary for photometry (measuring star brightness) and it also helps enhance detail in images. The refractor images tend to look far better when flat-fielding is done. However, if you are in a rush and willing to sacrifice quality, you may skip this section.1. Turn the white
dome lights on with the right switch
(Yes, they will destroy your
night vision, but this must be done after focusing). If it is a buggy
time of year, close the shutters so they do not all come in.
2. Reflector only - Use the dome controller
to point the white poster to the south, but slightly off to the side.
(Yes, they will destroy your
night vision, but this must be done after focusing). If it is a buggy
time of year, close the shutters so they do not all come in.2. Reflector only - Use the dome controller
to point the white poster to the south, but slightly off to the side.3. Plug in and turn on the
light source.
4. Reflector only - Aim the telescope at the white poster
Refractor only - Place the diffuser mask on the refractor and
point the refractor at the light source.
5. Lock down the right ascension
and declination
knobs.
6. Tag your images. The Setup tab has an option for File Defaults. Type in your name and the telescope information. The following shows the information for the reflector. The refractor should have the following settings: Description="Refractor", Focal Length="600", Aperture area="7854", Aperture diameter="100"
7. Auto-save your images. Switch to the AutoSave tab. Everything should match the window below except the the folder to save it in. The convention for saving files is to put them in a folder with the date. For example, images taken on 8/18/06 should be saved in "C:\Documents and Settings\ccd\My Documents\CCD images\8.18.06" Set the File name to flat.
8. Change to the Take Image tab. Set the frame type to Light and Reduction to Auto-dark. Why not flat frame?
9. Switch to the Color tab. Make the settings match the window below by
clicking on the Edit buttons. You may need to adjust exposure times,
depending on the setup. Ideally the average pixel value should be
around 30,000 (the scale is 1 to 65,535). You can check this by
hovering the cursor over the image and watching the bottom left corner
of the screen.
4. Reflector only - Aim the telescope at the white poster
Refractor only - Place the diffuser mask on the refractor
and
point the refractor at the light source.5. Lock down the right ascension
and declination
knobs.6. Tag your images. The Setup tab has an option for File Defaults. Type in your name and the telescope information. The following shows the information for the reflector. The refractor should have the following settings: Description="Refractor", Focal Length="600", Aperture area="7854", Aperture diameter="100"
7. Auto-save your images. Switch to the AutoSave tab. Everything should match the window below except the the folder to save it in. The convention for saving files is to put them in a folder with the date. For example, images taken on 8/18/06 should be saved in "C:\Documents and Settings\ccd\My Documents\CCD images\8.18.06" Set the File name to flat.
8. Change to the Take Image tab. Set the frame type to Light and Reduction to Auto-dark. Why not flat frame?
10. Click on Take Color to
take a shot through each filter.
11. For high-precision work, repeat step 10 but move the telescope slightly. You can average these frames later. Three sets of images will do.
11. For high-precision work, repeat step 10 but move the telescope slightly. You can average these frames later. Three sets of images will do.
What do you want to
take a picture of? Chances are, you already came with some ideas, but
not everything is easy to image. First
off, the camera is ill-suited for planetary and lunar work. The moon is
far too
bright for the sensitive pixels and furthermore, the atmospheric
turbulence around the dome makes resolving fine details near
impossible. If you decide to image a planet anyway, use a mask
to stop down the aperture.
For the refractor, bigger nebulas and close galaxies work well, but rarely do they fill the whole screen. Andromeda is the only galaxy that fills the entire chip. The C14 reflector is suited for smaller nebulas and almost all galaxies. To see what the frame sizes are, see the section on star hopping.
If you have no ideas on where to start, try using the Starry Night Pro planetarium program, located on the desktop. Click OK on the registration screen. Once it has loaded, go to the options tab and select the "labels" checkboxes next to Messier objects and bright NGC objects. This will show you in the sky what sort of objects are up. The following section shows how to find these objects if you are unfamiliar with telescopes. Bright objects with a magnitude less than 8 can usually be found easily. Dimmer objects might require more hunting around.
The most important recommendation is DON'T IMAGE OBJECTS AT THE ZENITH (straight overhead). This position can be extremely awkward for viewing, tracking and pointing through the dome. Conversely, imaging right on the horizon is unwise because there tends to be considerable light pollution and atmospheric distortion. Altitudes of 30 to 75 degrees work well.
to stop down the aperture.For the refractor, bigger nebulas and close galaxies work well, but rarely do they fill the whole screen. Andromeda is the only galaxy that fills the entire chip. The C14 reflector is suited for smaller nebulas and almost all galaxies. To see what the frame sizes are, see the section on star hopping.
If you have no ideas on where to start, try using the Starry Night Pro planetarium program, located on the desktop. Click OK on the registration screen. Once it has loaded, go to the options tab and select the "labels" checkboxes next to Messier objects and bright NGC objects. This will show you in the sky what sort of objects are up. The following section shows how to find these objects if you are unfamiliar with telescopes. Bright objects with a magnitude less than 8 can usually be found easily. Dimmer objects might require more hunting around.
The most important recommendation is DON'T IMAGE OBJECTS AT THE ZENITH (straight overhead). This position can be extremely awkward for viewing, tracking and pointing through the dome. Conversely, imaging right on the horizon is unwise because there tends to be considerable light pollution and atmospheric distortion. Altitudes of 30 to 75 degrees work well.
| Contents | Previous | Next |
Using the Digital Setting Circles
Finding dim deep-sky
objects requires good knowledge of the night sky and some experience.
If you are comfortable finding things through a telescope, do so now
and skip
this section. Otherwise,
you can use the digital setting circles.
1. Choose a star in the guide star catalog, preferably away from the north or south celestial poles. This is where knowledge of a few constellations is necessary. The catalog can be accessed in three ways.
a. There are printed sky charts
in the north most cabinet .
b. Use the Starry Night Pro software (opened from the desktop or start menu). Once you have clicked OK to the registration and loaded the program, find the Options tab. Click on Sky Commander Guide stars under the Other menu and click on the "label" checkbox. This will label all the DSC stars.
c. If you are already familiar with common star names, you can scroll through the catalog with the up and down keys in step 4.
2. Connect the DSC power chord to
the Losmandy digital drive system box 12V DC port .
1. Choose a star in the guide star catalog, preferably away from the north or south celestial poles. This is where knowledge of a few constellations is necessary. The catalog can be accessed in three ways.
a. There are printed sky charts
in the north most cabinet 
.b. Use the Starry Night Pro software (opened from the desktop or start menu). Once you have clicked OK to the registration and loaded the program, find the Options tab. Click on Sky Commander Guide stars under the Other menu and click on the "label" checkbox. This will label all the DSC stars.
c. If you are already familiar with common star names, you can scroll through the catalog with the up and down keys in step 4.
2. Connect the DSC power chord
to
the Losmandy digital drive system box 12V DC port 
.2. Connect the mount's
optical encoders
to the Losmandy DSC box.
3. Flip the power switch on and you will see a screen with the date. Set it to the day after the current one (unless it is past 12AM - in this case, set the day to the current day). Press E for enter.
to the Losmandy DSC box.3. Flip the power switch on and you will see a screen with the date. Set it to the day after the current one (unless it is past 12AM - in this case, set the day to the current day). Press E for enter.
4. When the next screen has
loaded, select one star align by pressing the up arrow.
5. Take an image of the
guide star with the CCD using the same procedure as in the alignment
section. First center the dome slit on the guide star and find it in
the Telrad ,
then center it on the camera with the computer (Reflector setup must
use the finderscope ).
If you need to review the process, return to the alignment
section.
6. When you have the guide star directly centered on the camera chip, press the left or right arrow to select either 1st star or 2nd star depending on which side of the meridian you are on. West of meridian = 2nd star. East of meridian = 1rst star. Note: The number just refers to the side of the horizon. You will be aligning with only one star.
7. Use the down and up arrows to select the name of the guide star that you have in the camera now. In the above example, the star is Alpha Cassiopeiae.
8. Press E to align. You will now be in the main screen.
5. Use the arrow keys to select an object by it's Messier number, NGC number, or planet name. For example, if you were going to find NGC 7635 (The bubble nebula), you would first move the cursor (_) under 'Mes' with the left and right arrows. Then you would press down so that the NGC catalog is displayed. Finally, you would use the cursor (_) to select 7635.
6. Once the object has been selected, press E for enter. The underscore cursor should move to the left of the numbers. Once it is there, press the up arrow to select relative position. This is indicated by an asterisk.
7. Move the telescope so that the right ascension and declination are zeroed out. Lock down the declination
first, then the right ascension .
A more complete manual on the digital setting circles is available here.
Autoguider Calibration
The camera has the ability to control the telescope so that it corrects
for any tracking errors that may occur in the mount. A separate CCD
chip, called the autoguider is used to follow a guide star.
At this point, you should have acquired an object to image. If it is a
bright planet or you are willing to take noisier short pictures, so you
may skip this section.
.
1x1 bin and auto-darked images are best.
2. Change the radio button back to Imager.
Go to the Autoguider tab and change the settings to match the window
below. Click on Take Image.
3. Ideally, there should be many suitable calibration stars in the frame. If not, try moving the telescope slightly with the hand paddle or increasing exposure time.
4. Switch the hand controller cable and the relay cable so that the computer controls the drive motors.
5. Click on the calibrate button to initiate. The X and Y direction should move 20 seconds each.
Calibrating
the
Autoguider - (Reflector
setup only - click
to skip)
1. Go to the Take Image tab in CCDsoft and select the autoguider radio button.
Match your settings with the window below. 3x3 bin and auto-darked
images are best.
2. Change the radio button back to Imager.
3. Look through the finderscope. If the eyepiece illuminator is on,
you should see some red crosshairs.
The following diagram shows approximately where the autoguider is
inside the finderscope eyepiece .
4. Find a suitable calibration star in the eyepiece.
It should be
completely BY ITSELF with no other stars as bright nearby. Almost any
star that can be seen in the finderscope will do, but the brighter the
better. Using the hand controller ,
move the telescope so that a suitable guide star is inside the
autoguider area .
5. In CCDsoft, click on the Autoguide tab in the Camera Control window. Make the settings match the window below. Click Take Image. A bright star should be visible in the autoguider frame. If not, keep trying to place the star where it should be in the finderscope eyepiece
or increase exposure time if needed.
Another method for placing the
guide star is available in the autoguide
trouble appendix.
6. Once the star is in the autoguider frame, switch the hand controller cable and the relay cable so that the computer controls the drive motors.
8. Click on the Calibrate button. Set the X move and Y move to 6
seconds. The star will move during the process.
If calibration is successful, it will briefly say so in the status
bar .
If not, you will likely get a message that there was insufficient
movement .
This is the standard error if anything goes wrong. Try again with
longer exposures, different stars or see the appendix on autoguider
trouble.
9. If the calibration is successful, the software will briefly say so in the status bar of the Camera Control window.
Move the telescope back
to the object you wish to image. To do this, you may have to plug the
hand controller back in .
10. Look in the eyepiece of the finderscope.
If there is a star right in the autoguider area, you are in luck - skip to step 13.
Otherwise, search the nearby area for a suitable guide star. If none is
available, you can try the alternative method in the autoguider
trouble appendix.
11. Switch the hand paddle and camera relay wires again so that you can use the hand paddle.
1. Organize your images. The following diagram gives a good folder structure to follow. It is important to have the images labeled by their name and to know where the flat frames and dark frames are. If there are many different exposure times, it is useful to label the dark frames with the exposure duration in the title.
2. Click on "Image | Reduce | Image Reduction ..." to open up the reduction window.
3. Click "+" on a reduction group (any will do) to open up the frame folders.
4. Delete any old images in that reduction group.
5. Click on Dark Frames and then click the Add Frames button. In the selection window, select all relevant dark frames (those with equivalent exposure time to the image you are working on). Control-clicking will allow you to select multiple frames. Do the same for Flat-frames, keeping in mind a specific filter. Skip bias frames and Darks for Flats only. Why?
Note: Multiple frames are averaged to increase the signal to noise ratio.
Note: If you do not have flat-frames, delete any old ones with the Remove button.
5. Once the relevant frames are loaded, use the Reduce or Reduce Folder command to reduce an entire folder of images. If a whole folder is to be reduced, nothing else can be inside that folder.
6. Repeat steps 3-5 for all images, treating each filter separately.
Raw CCD images have millions of pixels. Each pixel can range in value from 1 to 65,535. Often, most of the detail is contained in a range of a few thousand brightness values. Honing this area is easy and non-destructive. We simply adjust the black point and white point, which set the maximum and minimum brightness. This technique, along with being easy, is one of the most effective tools for enhancing faint nebulosity.
1. Open up the desired image.
2. Open the histogram editor by clicking "Image | Brightness & Contrast | Histogram..."
3. Adjust the green sliders until the desired detail is reached. Putting the white point (left triangle) at the first peak of dark pixels
tends to help cut out any background noise.
4. Save the image when you are done. You can always adjust the histogram again without destroying anything.
Note: this should only be done after images have been reduced.
1. Place all images to be stacked in a folder with no other files.
2. Select "Image | Align | Align Folder of Images"
3. Select the correct folder.
4. Select the folder to place the aligned images in. You should create another folder in a similar spot, but it needs to be outside of the un-aligned shots.
5. Click Align.
6. Select "Image | Combine | Combine Folder of Images"
7. Select the folder that contains the aligned images.
8. Select the Add function.
9. Click Combine.
1. Click on "Image | Brightness & Contrast | Mid-Range Brighten". The modified image will open in a new window, leaving the original untouched.
For color shots, you need to have at least one exposure through red, green, and blue filters. A luminous shot is desirable, but not necessary. If you have multiple shots through each filter, they should be combined, as described in the multiple image combination section. This leaves you with a master luminance, red, green and blue.
1. Align the images as described in the the multiple image combination section. Open them with CCDsoft.
2. Select "Image | Color | Color Combine..."
3. In the new window, make sure that the red, green, blue and luminance (if you have one) selections match the appropriate shots.
4. If there is no color preview, click on the Preview button. It may be necessary to shrink this window by pressing Alt-3.
5. Adjust the color sliders until the majority of the stars are white. You can also compare your image with published ones to reach the appropriate color balance.
6. Click on Combine.
7. Repeat steps 5-6 several times until you have a few versions. Compare them and choose the best.
Note: You may wish to adjust the background and range of the individual filter shots first. Modifications to the luminance affect results more than modifications of the red, green or blue.
1. Find the magnitude of a particular star in the image. It should not be a variable.
2. Click on the set magnitude button.
,
declination axis ,
or both.
1. If the declination and
right ascension knobs
have been tightened, turn them counter-clockwise
until they feel loose.
2. Move the telescope with the two D rings
located on the sides.
Point it directly West. If the telescope moves when you
let go, it is imbalanced in declination.
3. Rotate the right ascension axis so the counterweights bar is horizontal. If the moves from the horizontal position, it is imbalanced in right ascension.
4. IMPORTANT - Lock down the right ascension
and declination
knobs. You don't want things swinging around as you adjust them.
5. If there is a small amount of imbalance on the right ascension axis, you may
compensate for it by moving back and forth the small brass weights on
the end of the telescope .
Do NOT move the large counterweights unless it is absolutely necessary.
If it is necessary, turn on the dome lights. To move a large
counterweight, loosen the lock knob slightly and screw the
counterweight in the desired direction. Do not move the counterweight
with the brass ones attached.
Check to make sure all lock knobs for counterweights are secure before proceeding.
6. If there is imbalance in the declination axis, you have to decide whether it is tolerable or not because this procedure can be very tricky: Please read through it before beginning.
a. Remove the camera so that if the telescope drops, at least the camera is not destroyed. (See cleanup for procedure)
b. Brace your arm and shoulder against the telescope back with all your might (you will be holding up about 60% of the weight of everything but you will have friction to help you).
c. Loosen the two lock knobs so that you can slide the telescope forward or backward to change the weighting
7. Retest the balance and make further adjustments if necessary.
1. Find a really bright object in the sky, preferably a planet like Jupiter, but a bright star will work as well. Avoid using the moon.
2. Prepare the camera to take continuous, short exposures as described in the alignment section.
3. Make sure the right ascension
and declination
knobs are loose. Point the telescope's Telrad
at the bright object.
4. If the camera does not record the planet or star, make circles around it by pointing the telrad. Start with small circles, and move outward while watching the computer the whole time. When the object is in view, it will probably streak across the screen.
5. Adjust the telrad as in the alignment section, step 9 so that the target centers the star.
6. (Reflector setup only) If the finderscope is off, re-center the star/planet as in the alignment section, step 10.
If the focus is way off, so that stars are unreasonably large or have holes in the center, it is probably necessary to take out the camera and make some adjustments.
1. Remove the camera as described in the cleanup section, step 11. You can leave the power on and set it in the padded case, as long as you are careful and put on the dust cap.
2. Attach the ground glass
in place of where the camera goes.
3. Point the telescope at a bright star (Not a planet!), making sure the right ascension
and declination
knobs are loose.
4. There should be a disk visible on the ground glass, unless it is too far out of focus. Turn the SCT focus knob until the star becomes a point. You may have to turn it far to observe a change in size of the disk.
5. When the star has approached a point on the ground glass, it should be very close if not exactly where the camera should focus. Proceed with the normal focusing procedure.
The standard message for any kind of problem is that there was insufficient movement in the X or Y direction. This error sometimes describes the problem and sometimes not. Here are some tips:
,
then center it on the camera with the computer (Reflector setup must
use the finderscope ).
If you need to review the process, return to the alignment
section.6. When you have the guide star directly centered on the camera chip, press the left or right arrow to select either 1st star or 2nd star depending on which side of the meridian you are on. West of meridian = 2nd star. East of meridian = 1rst star. Note: The number just refers to the side of the horizon. You will be aligning with only one star.
|
|
 |
 |
7. Use the down and up arrows to select the name of the guide star that you have in the camera now. In the above example, the star is Alpha Cassiopeiae.
8. Press E to align. You will now be in the main screen.
5. Use the arrow keys to select an object by it's Messier number, NGC number, or planet name. For example, if you were going to find NGC 7635 (The bubble nebula), you would first move the cursor (_) under 'Mes' with the left and right arrows. Then you would press down so that the NGC catalog is displayed. Finally, you would use the cursor (_) to select 7635.
6. Once the object has been selected, press E for enter. The underscore cursor should move to the left of the numbers. Once it is there, press the up arrow to select relative position. This is indicated by an asterisk.
7. Move the telescope so that the right ascension and declination are zeroed out. Lock down the declination
first, then the right ascension .8. (Refractor only)
Take a quick exposure of the object with the Focus Tools tab .
(Reflector only) Look through the finderscope.
If you are looking for a relatively bright object, it should appear somewhere in the field of view as a gray blob. If you are hunting for a very dim object that cannot be seen right away, you can try a longer exposure or you can adjust the background and range. If the object is not visible, see the section on star-hopping.
9. Center the object by using the hand controller.
The section on aligning contains the directional
information.
.(Reflector only) Look through the finderscope
.If you are looking for a relatively bright object, it should appear somewhere in the field of view as a gray blob. If you are hunting for a very dim object that cannot be seen right away, you can try a longer exposure or you can adjust the background and range. If the object is not visible, see the section on star-hopping.
9. Center the object by using the hand controller
.
The section on aligning contains the directional
information.A more complete manual on the digital setting circles is available here.
| Contents | Previous | Next |
Autoguider Calibration
The camera has the ability to control the telescope so that it corrects
for any tracking errors that may occur in the mount. A separate CCD
chip, called the autoguider is used to follow a guide star.
At this point, you should have acquired an object to image. If it is a
bright planet or you are willing to take noisier short pictures, so you
may skip this section.Calibrating the Autoguider (Refractor setup only - click to skip to reflector)
1. Go to the Take Image tab in CCDsoft and select the autoguider radio button
.
1x1 bin and auto-darked images are best.2. Change the radio button back to Imager
.
Go to the Autoguider tab and change the settings to match the window
below. Click on Take Image.3. Ideally, there should be many suitable calibration stars in the frame. If not, try moving the telescope slightly with the hand paddle or increasing exposure time.
4. Switch the hand controller cable and the relay cable so that the computer controls the drive motors.
5. Click on the calibrate button to initiate. The X and Y direction should move 20 seconds each.
6. If calibration is
successful, it will briefly say so in the status bar .
If not, you will likely get a message that there was insufficient
movement .
Try increasing the exposure time if you receive the error message.
Sometimes the
star can drift out of the screen during calibration. In this case, see
the reflector
section on calibration star placement.
7. Click the Autoguide button. The telescope will now exactly follow one star.
.
If not, you will likely get a message that there was insufficient
movement .
Try increasing the exposure time if you receive the error message.
Sometimes the
star can drift out of the screen during calibration. In this case, see
the reflector
section on calibration star placement.7. Click the Autoguide button. The telescope will now exactly follow one star.
Calibrating
the
Autoguider - (Reflector
setup only - click
to skip)
1. Go to the Take Image tab in CCDsoft and select the autoguider radio button
.
Match your settings with the window below. 3x3 bin and auto-darked
images are best.2. Change the radio button back to Imager
.3. Look through the finderscope. If the eyepiece illuminator is on
,
you should see some red crosshairs.
The following diagram shows approximately where the autoguider is
inside the finderscope eyepiece .4. Find a suitable calibration star in the eyepiece
.
It should be
completely BY ITSELF with no other stars as bright nearby. Almost any
star that can be seen in the finderscope will do, but the brighter the
better. Using the hand controller ,
move the telescope so that a suitable guide star is inside the
autoguider area . 5. In CCDsoft, click on the Autoguide tab in the Camera Control window. Make the settings match the window below. Click Take Image. A bright star should be visible in the autoguider frame. If not, keep trying to place the star where it should be in the finderscope eyepiece
or increase exposure time if needed.
Another method for placing the
guide star is available in the autoguide
trouble appendix.6. Once the star is in the autoguider frame, switch the hand controller cable and the relay cable so that the computer controls the drive motors.
7. Depending on if you are
on the
western or eastern side of the meridian, put the
star near the
appropriate corner, but not too close, because it will move during
calibration.
.
If not, you will likely get a message that there was insufficient
movement .
This is the standard error if anything goes wrong. Try again with
longer exposures, different stars or see the appendix on autoguider
trouble.9. If the calibration is successful, the software will briefly say so in the status bar of the Camera Control window
.
Move the telescope back
to the object you wish to image. To do this, you may have to plug the
hand controller back in .10. Look in the eyepiece of the finderscope
.
If there is a star right in the autoguider area, you are in luck - skip to step 13.
Otherwise, search the nearby area for a suitable guide star. If none is
available, you can try the alternative method in the autoguider
trouble appendix.11. Switch the hand paddle and camera relay wires again so that you can use the hand paddle.
12. Looking through the
finderscope, move the autoguider
area
to a suitable guide star with the hand paddle .
13. IMPORTANT - Remember to plug the relay cable in
if it has been unplugged.
Click on the Take
Image button to make sure the guide star is on the chip. If it is,
click on the Autoguide button to begin autoguiding.
to a suitable guide star with the hand paddle .13. IMPORTANT - Remember to plug the relay cable in
if it has been unplugged.
Click on the Take
Image button to make sure the guide star is on the chip. If it is,
click on the Autoguide button to begin autoguiding.Grayscale Imaging
By now, you should have acquired an object to image and
started the autoguiding. The last step is to take the images
themselves. The procedure from this point is flexible and depends
highly on what you are looking at. Most likely, capturing great
exposures will require
a little playing around. The following guidelines will help, but feel
free to adapt the settings to your needs.
1. Tag your images. The Setup tab has an option for File Defaults. Type in your name and the telescope information. The following shows the information for the reflector. The refractor should have the following settings: Description="Refractor", Focal Length="600", Aperture area="7854", Aperture diameter="100"
This is the main image-capture window, where most changes will be made:
IMAGE: Set to Light frame and set Reduction to None. The image reduction will occur later in post-processing.
Imager/Autoguider radio button: Use the Imager.
Take Image/Take Series button: Click here to begin the exposure.
4. Click on the Take Color/Take Series button to begin. The camera has a built-in color wheel that will change filters between shots.
1. Tag your images. The Setup tab has an option for File Defaults. Type in your name and the telescope information. The following shows the information for the reflector. The refractor should have the following settings: Description="Refractor", Focal Length="600", Aperture area="7854", Aperture diameter="100"
2. Auto-save your images.
Switch to the
AutoSave tab. Everything should match the window below except the File
name prefix name and the folder to save it in. The convention for
saving
files is to put them in a folder with the date. For example, images
taken on 8/18/06 should be saved in "C:\Documents and Settings\ccd\My
Documents\CCD images\8.18.06"
3. Capture your images
3. Capture your images
This is the main image-capture window, where most changes will be made:
EXPOSURE (Minutes,
Seconds): Here is
where you will set your exposure length. The main idea is to take
as long an exposure as possible. The more signal you have, the greater
the signal to noise ratio and the better the picture; however, if
exposures are too long, you will begin to see blooming .
Try to take exposures that come close to blooming, but don't exceed the
maximum pixel value (saturation). If you hold the cursor over a
star, the pixel value is displayed in the lower left corner.
They
should range in value from 1 to 65,535. Sometimes, blooming will be
necessary in order to image faint nebulosity.
For the refractor, 1 minute exposures are generally long enough to capture good detail. Taking several images and stacking them up later will allow total exposures of 10 minutes or more.
For the C14 reflector, longer exposures are usually necessary. Galaxies and nebulosity usually need more than five minutes to achieve good signal to noise ratios.
Planets should be imaged with as short an exposure as possible (0.1 seconds is as fast as our camera goes).
DELAY (seconds): Sets the time the camera will wait before opening the shutter. Often, it is useful to set a 15 second delay before an image to give enough time to go downstairs and stay away from disturbing the system during an exposure. If you choose to sit and watch the images right at the computer, set the delay to zero.
SERIES OF: This option allows several images to be taken in a row. When used, the Take Image button changes to a Take Series button.
FILTER: Generally, the luminance filter should be used to take images. Color shots will be described in the next section.
TO NEW WINDOW: Leave off, unless you want to compare images.
SUBFRAME: Leave off unless you are focusing.
BIN: For high-resolution images in the refractor, 1x1 binning is best. However, with the reflector, 3x3 binning is better for two reasons: the seeing conditions make high resolution images unnecessary and 3x3 binning will be brighter.
.
Try to take exposures that come close to blooming, but don't exceed the
maximum pixel value (saturation). If you hold the cursor over a
star, the pixel value is displayed in the lower left corner.
They
should range in value from 1 to 65,535. Sometimes, blooming will be
necessary in order to image faint nebulosity.For the refractor, 1 minute exposures are generally long enough to capture good detail. Taking several images and stacking them up later will allow total exposures of 10 minutes or more.
For the C14 reflector, longer exposures are usually necessary. Galaxies and nebulosity usually need more than five minutes to achieve good signal to noise ratios.
Planets should be imaged with as short an exposure as possible (0.1 seconds is as fast as our camera goes).
DELAY (seconds): Sets the time the camera will wait before opening the shutter. Often, it is useful to set a 15 second delay before an image to give enough time to go downstairs and stay away from disturbing the system during an exposure. If you choose to sit and watch the images right at the computer, set the delay to zero.
SERIES OF: This option allows several images to be taken in a row. When used, the Take Image button changes to a Take Series button.
FILTER: Generally, the luminance filter should be used to take images. Color shots will be described in the next section.
TO NEW WINDOW: Leave off, unless you want to compare images.
SUBFRAME: Leave off unless you are focusing.
BIN: For high-resolution images in the refractor, 1x1 binning is best. However, with the reflector, 3x3 binning is better for two reasons: the seeing conditions make high resolution images unnecessary and 3x3 binning will be brighter.
IMAGE: Set to Light frame and set Reduction to None. The image reduction will occur later in post-processing.
Imager/Autoguider radio button: Use the Imager.
Take Image/Take Series button: Click here to begin the exposure.
If the image is too large
for the screen ,
press Alt-3 to make it smaller .
(Control 2,3, and 4 zoom in while Alt 2,3,4 zoom
out. Control-1 = Alt-1 = normal size.)
,
press Alt-3 to make it smaller 
.
(Control 2,3, and 4 zoom in while Alt 2,3,4 zoom
out. Control-1 = Alt-1 = normal size.)Important note about image capture:
The telescope is
highly sensitive to any small vibrations. If you simply walk around the
pier, you can ruin an entire 10 minute image. This
means you should tiptoe
and move very slowly during an exposure. Another option is to set the
delay to 15
seconds and
leave the area during the delay before exposure time. Feel free to gaze
at the stars
from the deck in the interim.
One thing to occasionally check up on is dome cutoff. Keep the dome slit aimed
so that the Telrad target
stays approximately in the center of the dome slit. Unlike
walking on the floorboards, this vibration does not ruin images.
One thing to occasionally check up on is dome cutoff. Keep the dome slit aimed
so that the Telrad target
stays approximately in the center of the dome slit. Unlike
walking on the floorboards, this vibration does not ruin images.| Contents | Previous | Next |
Color Imaging
Color pictures are
made by assembling images taken through luminance, red, green and blue
(LRGB) filters. You need to capture separate exposures through each
filter and combine them later. The camera will be most sensitive
through the luminance (no blockage) and least sensitive through the
blue filter, so exposure length may vary.
1. Read the grayscale imaging section first so you set your tag and autosave information.
2. Switch to the Color Tab to set the color settings.
1. Read the grayscale imaging section first so you set your tag and autosave information.
2. Switch to the Color Tab to set the color settings.
3. Change each menu by
clicking on the
Edit button. You will be prompted with a small window in which you can
change the settings. Leave the Filter options as they are. For the refractor, 1
minute exposures through each filter work well. For the reflector,
10 minute exposures through each filter work well. However, you may
adjust the times to favor the blue exposures. If the times are all
different, it can complicate taking dark frames (next section). For
most situations, take 1 through each filter. Set the bin to
1x1 for the refractor
and to 3x3 for the
reflector.
4. Click on the Take Color/Take Series button to begin. The camera has a built-in color wheel that will change filters between shots.
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Capturing Dark Frames
The images you have
captured so far probably contain a salt-like smattering of bright
pixels on top of the galaxy/nebula/star cluster. Most of these pixels
are the result of dark
current, not distant stars. You can subtract out these pixels
by taking dark
frames.
1. Switch back to the Take Image tab and select Dark frame.
2. If you took grayscale images, click on Take Image to capture dark frames with equivalent exposure time and Bin mode. If you took color images, click on Take Color in the Color Tab. IMPORTANT: Make sure you have exactly the same exposure time and bin mode as before. Old images can be re-opened and 'View | File Information' will tell you the duration of the exposures. As they are taken, the Status bar will show the progress.
1. Switch back to the Take Image tab and select Dark frame.
2. If you took grayscale images, click on Take Image to capture dark frames with equivalent exposure time and Bin mode. If you took color images, click on Take Color in the Color Tab. IMPORTANT: Make sure you have exactly the same exposure time and bin mode as before. Old images can be re-opened and 'View | File Information' will tell you the duration of the exposures. As they are taken, the Status bar will show the progress.
3. Take several dark
exposures, so they
can be averaged. If they are 10 minutes or longer, you can get by with
only one, but shorter exposures, like 1 minute should be taken thrice
and averaged.
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Cleanup
If you are still interested in taking more shots and it isn't too late
in the morning, return to selecting
and object.
It will be necessary to re-calibrate the autoguider, but dark frames
may be re-used if they are the same exposure length. If you are
exhausted and ready for bed, proceed on.
You may turn on the white dome lights for illumination.
1. Close all software programs. They will automatically disconnect the devices.
2. Turn off the camera power with the I/O switch.
3. Turn off the Telrad
by fully closing the dimmer switch.
4. Reflector only (Click to skip). Turn off the Robofocuser.
5. Reflector only. Turn off the reticle illuminator
and store it in the eyepiece
cabinet .
6. Refractor only - Disconnect the Robofocuser and coil up the wires.
7. Disconnect the camera connections one by one. Coil up the power chord,
relay box
and USB cable .
Connect the
hand paddle
if it has been unplugged.
8. "Park" the telescope by pointing it upright and north.
9. Remove the dew shield
and put the lid back on .
10. Lock down the right ascension
and declination
knobs.
11. Untie the camera's strap.
12. Loosen the set screws (Refractor
Reflector )
that hold the
camera and carefully remove it from the telescope. Put the camera back
in the padded case.
13. Replace the eyepiece where camera was (Refractor
Reflector ).
14. Loosen the right ascension
and declination
knobs.
15. Retrieve the dust cover and put it back on the telescope with the strings hanging on either side of the counterweights.
16. Return the dome so that it faces directly east.
17. Close the dome shutters with the filter wheel.
18. Close and lock each window and door behind you. Be sure to turn off all lights.
You may turn on the white dome lights for illumination
.1. Close all software programs. They will automatically disconnect the devices.
2. Turn off the camera power with the I/O switch
.3. Turn off the Telrad
by fully closing the dimmer switch.4. Reflector only (Click to skip). Turn off the Robofocuser
.5. Reflector only. Turn off the reticle illuminator
and store it in the eyepiece
cabinet .6. Refractor only - Disconnect the Robofocuser and coil up the wires.
7. Disconnect the camera connections one by one. Coil up the power chord
,
relay box
and USB cable .
Connect the
hand paddle
if it has been unplugged.8. "Park" the telescope by pointing it upright and north
.9. Remove the dew shield
and put the lid back on .10. Lock down the right ascension
and declination
knobs.11. Untie the camera's strap
.12. Loosen the set screws (Refractor
Reflector )
that hold the
camera and carefully remove it from the telescope. Put the camera back
in the padded case.13. Replace the eyepiece where camera was (Refractor
Reflector 
).14. Loosen the right ascension
and declination
knobs.15. Retrieve the dust cover and put it back on the telescope with the strings hanging on either side of the counterweights
.16. Return the dome so that it faces directly east
.17. Close the dome shutters with the filter wheel
.18. Close and lock each window and door behind you. Be sure to turn off all lights.
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Image Reduction
Post processing is best done in the daylight, but if you are eager to see some color shots, you may proceed anyway. The following procedure uses CCDsoft, but MIRA or any image-processing program would work as well.1. Organize your images. The following diagram gives a good folder structure to follow. It is important to have the images labeled by their name and to know where the flat frames and dark frames are. If there are many different exposure times, it is useful to label the dark frames with the exposure duration in the title.
2. Click on "Image | Reduce | Image Reduction ..." to open up the reduction window.
3. Click "+" on a reduction group (any will do) to open up the frame folders.
4. Delete any old images in that reduction group.
5. Click on Dark Frames and then click the Add Frames button. In the selection window, select all relevant dark frames (those with equivalent exposure time to the image you are working on). Control-clicking will allow you to select multiple frames. Do the same for Flat-frames, keeping in mind a specific filter. Skip bias frames and Darks for Flats only. Why?
Note: Multiple frames are averaged to increase the signal to noise ratio.
Note: If you do not have flat-frames, delete any old ones with the Remove button.
5. Once the relevant frames are loaded, use the Reduce or Reduce Folder command to reduce an entire folder of images. If a whole folder is to be reduced, nothing else can be inside that folder.
6. Repeat steps 3-5 for all images, treating each filter separately.
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Adjusting Background and Range
Raw CCD images have millions of pixels. Each pixel can range in value from 1 to 65,535. Often, most of the detail is contained in a range of a few thousand brightness values. Honing this area is easy and non-destructive. We simply adjust the black point and white point, which set the maximum and minimum brightness. This technique, along with being easy, is one of the most effective tools for enhancing faint nebulosity.
1. Open up the desired image.
2. Open the histogram editor by clicking "Image | Brightness & Contrast | Histogram..."
3. Adjust the green sliders until the desired detail is reached. Putting the white point (left triangle) at the first peak of dark pixels
tends to help cut out any background noise.4. Save the image when you are done. You can always adjust the histogram again without destroying anything.
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Stacking Multiple Images
If you wish to combine many short exposures, you can simply add pixel values. Do not use this for photometry, unless the pixels stay below 65,535 counts.Note: this should only be done after images have been reduced.
1. Place all images to be stacked in a folder with no other files.
2. Select "Image | Align | Align Folder of Images"
3. Select the correct folder.
4. Select the folder to place the aligned images in. You should create another folder in a similar spot, but it needs to be outside of the un-aligned shots.
5. Click Align.
6. Select "Image | Combine | Combine Folder of Images"
7. Select the folder that contains the aligned images.
8. Select the Add function.
9. Click Combine.
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Nonlinear Stretches
Sometimes, you may find that adjusting the background and range cuts out faint detail or saturates the bright cores of galaxies. For these situations, it is useful to try the Mid-Range Brighten. This tool "evens out" the image so that you can display dim outer structures without over-doing the brighter regions.1. Click on "Image | Brightness & Contrast | Mid-Range Brighten". The modified image will open in a new window, leaving the original untouched.
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Color Combining
For color shots, you need to have at least one exposure through red, green, and blue filters. A luminous shot is desirable, but not necessary. If you have multiple shots through each filter, they should be combined, as described in the multiple image combination section. This leaves you with a master luminance, red, green and blue.
1. Align the images as described in the the multiple image combination section. Open them with CCDsoft.
2. Select "Image | Color | Color Combine..."
3. In the new window, make sure that the red, green, blue and luminance (if you have one) selections match the appropriate shots.
4. If there is no color preview, click on the Preview button. It may be necessary to shrink this window by pressing Alt-3.
5. Adjust the color sliders until the majority of the stars are white. You can also compare your image with published ones to reach the appropriate color balance.
6. Click on Combine.
7. Repeat steps 5-6 several times until you have a few versions. Compare them and choose the best.
Note: You may wish to adjust the background and range of the individual filter shots first. Modifications to the luminance affect results more than modifications of the red, green or blue.
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Photometry
The magnitude of stars can be measured by using the CCDsoft program, or any similar CCD editor. You will need to know the magnitude of at least one star in the image in order to proceed. This can be found in any star catalog, but it requires that you know where in the sky the image was taken. TheSky, a planetarium program, has the capability to align your image with its catalog.1. Find the magnitude of a particular star in the image. It should not be a variable.
2. Click on the set magnitude button.
3. Click on the star that
will be calibrated against. Type in the appropriate magnitude.
4. Measure the magnitude of stars, quasars, asteroids or comets with the determine magnitude button.
4. Measure the magnitude of stars, quasars, asteroids or comets with the determine magnitude button.
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Balance
One common balancing problem is electrical chords. Check first to make sure this is not the issue. If balance is off, you must figure out if it is in the right ascension axis
,
declination axis 
,
or both.1. If the declination
and
right ascension knobs
have been tightened, turn them counter-clockwise
until they feel loose.2. Move the telescope with the two D rings
located on the sides.
Point it directly West. If the telescope moves when you
let go, it is imbalanced in declination.3. Rotate the right ascension axis so the counterweights bar is horizontal. If the moves from the horizontal position, it is imbalanced in right ascension.
4. IMPORTANT - Lock down the right ascension
and declination
knobs. You don't want things swinging around as you adjust them.5. If there is a small amount of imbalance on the right ascension axis
, you may
compensate for it by moving back and forth the small brass weights on
the end of the telescope 
.
Do NOT move the large counterweights unless it is absolutely necessary.
If it is necessary, turn on the dome lights. To move a large
counterweight, loosen the lock knob slightly and screw the
counterweight in the desired direction. Do not move the counterweight
with the brass ones attached.Check to make sure all lock knobs for counterweights are secure before proceeding.
6. If there is imbalance in the declination axis, you have to decide whether it is tolerable or not because this procedure can be very tricky: Please read through it before beginning.
a. Remove the camera so that if the telescope drops, at least the camera is not destroyed. (See cleanup for procedure)
b. Brace your arm and shoulder against the telescope back with all your might (you will be holding up about 60% of the weight of everything but you will have friction to help you).
c. Loosen the two lock knobs so that you can slide the telescope forward or backward to change the weighting
7. Retest the balance and make further adjustments if necessary.
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Fixing Poor Alignment
Misalignment can take 20 minutes or more to fix, but should not have to be performed often.1. Find a really bright object in the sky, preferably a planet like Jupiter, but a bright star will work as well. Avoid using the moon.
2. Prepare the camera to take continuous, short exposures as described in the alignment section.
3. Make sure the right ascension
and declination
knobs are loose. Point the telescope's Telrad
at the bright object.4. If the camera does not record the planet or star, make circles around it by pointing the telrad. Start with small circles, and move outward while watching the computer the whole time. When the object is in view, it will probably streak across the screen.
5. Adjust the telrad as in the alignment section, step 9 so that the target centers the star
.6. (Reflector setup only) If the finderscope is off, re-center the star/planet as in the alignment section, step 10.
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Finding Focus - Reflector Setup
If the focus is way off, so that stars are unreasonably large or have holes in the center, it is probably necessary to take out the camera and make some adjustments.
1. Remove the camera as described in the cleanup section, step 11. You can leave the power on and set it in the padded case, as long as you are careful and put on the dust cap
.2. Attach the ground glass
in place of where the camera goes.3. Point the telescope at a bright star (Not a planet!), making sure the right ascension
and declination
knobs are loose.4. There should be a disk visible on the ground glass, unless it is too far out of focus. Turn the SCT focus knob until the star becomes a point. You may have to turn it far to observe a change in size of the disk.
5. When the star has approached a point on the ground glass, it should be very close if not exactly where the camera should focus. Proceed with the normal focusing procedure.
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Autoguider Trouble
Setting up the autoguider can be one of the most frustrating parts of CCD work at the Peters Observatory. If you are short on time or patience, you might want to try short exposures (15 seconds in the reflector and 45 seconds in the refractor) without autoguiding.Calibration Problems
The standard message for any kind of problem is that there was insufficient movement in the X or Y direction. This error sometimes describes the problem and sometimes not. Here are some tips:
- Choose another guide star (ie. move the telescope). Sometimes the software gets confused as to which star it should follow.
- Increase the calibration time to be sure that the star is registering.
- If you click on the Auto button, the computer will flash a box quickly in the region that the star calibrates on. If this box does not enclose a star, you need a longer exposure or a brighter star.
- Make sure the relay wire is plugged in .
Without this
cable, the computer has no control over the telescope.
- Place the calibration star in the appropriate corner, so that it does not move off of the screen.
- Make sure that the Losmandy Drive System settings are optimal
- Occasionally movement is actually too small. Increase the calibration time slightly.
- Depending on the refractor or reflector setup, make sure the autoguider binning mode is correct (refractor --> 1x1, reflector --> 3x3)
Alternative Star Placement
There is another method for
placing a guide star, whether for calibration or guiding.
1. Find a nice bright star in the imager window (the main CCD window). It will require the least work if this star is in the top middle.
2. Use the hand paddle (see directionality in the alignment section) to move the star straight off the top-middle of the imager window. Go a few seconds beyond until it shows up in the autoguider window.
1. Find a nice bright star in the imager window (the main CCD window). It will require the least work if this star is in the top middle.
2. Use the hand paddle (see directionality in the alignment section) to move the star straight off the top-middle of the imager window. Go a few seconds beyond until it shows up in the autoguider window.
Autoguide failure
If the autoguiding
fails midway through an exposure, it is usually because the camera has
paused and the star has drifted in the interim. Here are some tips:
- If you are taking color exposures, the blue filter can be so dim that the star is difficult to find. Try increasing autoguider exposure time.
- If the star is too dim, you may need to find another or increase exposure time. Hovering the cursor over the star will give you an idea of the pixel count. Above a value of 1000 is best.
- To see which star the software was following, click on the Auto button. This should draw a box around the star. If it does not follow the star you intended, simply click on the correct star. You should see a box flash around where you clicked and the computer will then follow that star.
- Sometimes, when the equatorial mount is out of alignment, the star drifts too fast to follow. Fine-tune polar alignment as described in the appendix.
- If need be, as a complete last resort, you can try turning the camera so that a favorable star lands on the autoguider. Unfortunately, this means re-focusing and re-calibrating (at an angle). To do this, loosen the camera's set screws and face the camera wires in the direction of the guide star. Note that directionality of the hand paddle will be rotated.
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Refining Polar Alignment
If the telescope does
not follow the stars well, it may be that polar alignment is off. You
can use the camera to help fine-tune polar alignment. Read the whole
procedure before executing becauset there are a few quick moves that
you need to make. The following is based off a procedure from http://www.ucihs.uci.edu/pandb/hall/polar.htm.
Altitude Refinement
1. Point the telescope to
either the East or West and find some relativley dim stars, magnitude
6 or fainter. You will be creating star streaks, so smaller stars will
make thinner lines.
2. Start a 65 second exposure, as described in the take image section.
3. After 5 seconds, turn off the losmandy drive system, remembering to ground your hand.
2. Start a 65 second exposure, as described in the take image section.
3. After 5 seconds, turn off the losmandy drive system, remembering to ground your hand.
4. Wait 30 seconds, then
turn on the
drive system again. Making sure to return the settings to 2X. Return
the star near its original position by holding the hand paddle
button
for another 30 seconds.
6. If there is a V, your goal it so make it a single line. Start by adjusting the altitude knob slightly in one direction. You may have to loosen the lock knob
first.
button
for another 30 seconds.5. The image will tell you
how far off
the alignment is. If the altitude alignment is perfect, you will see
one line. If it is not, you will see a V. The following diagrams were
taken from http://www.ucihs.uci.edu/pandb/hall/polar.htm.
6. If there is a V, your goal it so make it a single line. Start by adjusting the altitude knob slightly in one direction. You may have to loosen the lock knob
first.7. Repeat steps 2-6 again,
noting if the V becamer narrower or wider. Keep adjusting until you
approach a straight line.
Azimuth Refinement
1. Point the telescope at a
6th magnitude
or dimmer star near the zenith (straight overhead).
2. Repeat steps 2-5, but this time you will adjust the azimuth knobs.
You may need to loosen the left
and right
set screws first.
2. Repeat steps 2-5, but this time you will adjust the azimuth knobs
.
You may need to loosen the left 
and right
set screws first.3. Keep adjusting until you
get a straight line.
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Using the Planetarium Software
There are many planetarium programs loaded on both the Linux and
Windows computer. They include Hallo Northern Sky, Starry Night Pro,
TheSky and KStars. The following procedure shows how to use Starry
Night Pro as a celestial atlas.
1. Open Starry Night Pro
from the desktop.
2. Search for the object you are interested in finding by pressing "Control-f" and typing the name in. Hit Enter.
The object should appear in Starry Night Pro with a label.
3. Click OK in the registration window.
4. Go to the FOV tab and select the 2º and 4º checkboxes under Other (All Charts).
Refractor: Click on SBIG ST10XME under Refractor.
2. Search for the object you are interested in finding by pressing "Control-f" and typing the name in. Hit Enter.
The object should appear in Starry Night Pro with a label.
3. Click OK in the registration window.
4. Go to the FOV tab and select the 2º and 4º checkboxes under Other (All Charts).
Refractor: Click on SBIG ST10XME under Refractor
.
Reflector: Click on SBIG ST10XME under C14 .
5. You will now see a box and two circles. The circles represent the Telrad target
(4 degrees and 2 degrees). The box represents what the camera sees. Use
this box to gauge how big the object will appear in the final image.
Reflector
.5. You will now see a box and two circles. The circles represent the Telrad target
(4 degrees and 2 degrees). The box represents what the camera sees. Use
this box to gauge how big the object will appear in the final image.Refractor
Reflector
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The Basics of Star-Hopping
Before the days of settings circles and automatically-pointing
telescopes, amateur and professional astronomers used to resort to sky
charts to find celestial objects. The following procedure gives a rough
idea of the process using the Starry Night program as a guide. It is
simple in principle, but can be very frustating and tiring in practice.
1. As described in the previous section, set up the software to show you how big the Telrad circles will be.
2. Find a bright constellation near the object you are looking for. You may want to click on the stick figure option
to see the constellation figure.
Find it both in the sky and on the computer.
3. Using the arrow keys, center the object in the two Circles.
4. Using the position of those circles as a guide, align the Telrad target
in the same way. This will give close alignment.
5. Reflector Setup Only (Refractor setup can use the camera if necessary). For futhur alignment, zoom in closer with the computer. Flip the x and y axis so that it will appear as seen through the scope.
Look through the finderscope eyepiece
and identify some stars that are seen on the computer. For example, you
may notice the curved line of stars highlighted below. Make any
additional movements to find your object of interest.
ADU - Analog to digital unit
CCD - Charge Coupled Device
DSC - Digital setting circles
FITS - Flexible Image Transport System (image format)
FOV - Field of view (optical or for a pixel)
FWHM - Full width half maximum (width of 50% of brightest starlight)
JPEG - Joint Photographics Expert Group (image format)
LRGB - Luminance layer, red, green blue
NGC - New general catalog
PIXEL - Picture Element
PSF - Point spread function
SCT - Schmidt Cassegrain Telescope
SNR - Signal to Noise ratio
TE - Thermo electric (cooling)
TIFF - Tag image file format
UGC - Uppsala General Catalog
Written by Everett Schlawin
1. As described in the previous section, set up the software to show you how big the Telrad circles will be.
2. Find a bright constellation near the object you are looking for. You may want to click on the stick figure option
to see the constellation figure.
Find it both in the sky and on the computer.3. Using the arrow keys, center the object in the two Circles.
4. Using the position of those circles as a guide, align the Telrad target
in the same way. This will give close alignment.5. Reflector Setup Only (Refractor setup can use the camera if necessary). For futhur alignment, zoom in closer with the computer. Flip the x and y axis so that it will appear as seen through the scope.
Look through the finderscope eyepiece
and identify some stars that are seen on the computer. For example, you
may notice the curved line of stars highlighted below. Make any
additional movements to find your object of interest.| Contents | Previous | Next |
CCD Acronyms
ADU - Analog to digital unit
CCD - Charge Coupled Device
DSC - Digital setting circles
FITS - Flexible Image Transport System (image format)
FOV - Field of view (optical or for a pixel)
FWHM - Full width half maximum (width of 50% of brightest starlight)
JPEG - Joint Photographics Expert Group (image format)
LRGB - Luminance layer, red, green blue
NGC - New general catalog
PIXEL - Picture Element
PSF - Point spread function
SCT - Schmidt Cassegrain Telescope
SNR - Signal to Noise ratio
TE - Thermo electric (cooling)
TIFF - Tag image file format
UGC - Uppsala General Catalog
Written by Everett Schlawin