Observing Checklist for Imaging
with the 24" Telescope and ST9 CCD
using CCDObs + AO (Windows PC)
Linux commands are shown in italics.
Commands in the ucirob program (Linux PC) are in red.
Commands in Xephem/SkyView (Linux PC) are in green.
Commands in the CCDObs program (Windows PC) are in blue.
- Take the grey-colored cap off the
telescope baffle, which protects the instruments from dust.
- Log onto ucirob.ps as observer.
Before you start ucirob, the computer-controled AC power unit
should be cycled on/off. That's the red-lighted power switch
beside the large connector on the front of the black box in the
middle of the rack. Start ucirob, the observatory control program,
by doing 'ucirob &'. Open the observatory with Open Obs
and when completed (see message screen) make sure the mirror covers
are indeed all the way open. If not, open the cover gently with your
- Power up the Windows PC, in which you
will use the CCDObs program to control the CCD. If it isn't already
plugged in, plug the USB cable labeled ST9 into the laptop. Start the
- On the Windows PC, create your own
subdirectory for that night in which to store your images. Start
your entry in the Observatory Log Book noting the directory where your
images will be stored.
- Start Xephem (FILE/Start Xephem).
- Open the SkyView window in Xephem
- The scale button on LHS menu
changes coords to RA/DEC in SkyView.
- Toggle Live Report (top button on
RHS) to get cursor readout of RA/DEC.
- Once the observatory is open, in
Xephem 's SkyView bring up the Telescope/Configure
panel, and it should read "lx200xed" and "queue". Click on Show Sky View Marker. Click on Running. Then click on OK in the status window
at appears -- don't forget to do this because it completes the link
between Xephem and ucirob.
- Plot the CCD Field-of-View in
Xephem's SkyView by: (1) pulling down Control -> eyepieces - > ST9
(or whatever CCD it is), click Use
then close the window, and (2) right click and select Place Eyepieces.
- Check the pointing of the
telescope. In SkyView, put the cursor on a very bright star (e.g.,
Deneb, Vega or Arcturus) and right click to get information on
it. Right click, and hold down right button to Center and Zoom on the
object. To slew the telescope to it, right click, hold the mouse
button down, and slide to Telescope
- Power up the CCDs (CCDs button) in ucirob. Wait a minute
then click on the Establish Link button in CCDObs. You should see
the status of the CCD in the lower right corner of the window. Next set
operating temperature of the CCD (degrees Centigrade) by clicking on
the Setup button.
Set the Setpoint
to no more than 25 degrees below ambient or frosting will likely
on the CCD window, and turn the Temperature
Regulation to Active. Check
that the power doesn't exceed 80% once the operating temp is
reached. If it does you must raise the temp. If the dessicant in
the camera has not been baked lately, the CCD window may frost over if
the humidity is high and the operating temperature is low.
You'll notice it as a large-scale pattern on the CCD image,
similar to fog on your bathroom mirror. If frost occurs, raise the
temp (turn off temp reg) and take images until you find a temp that
works. Remember the lower the operating temp is the lower the dark
count and noise will be.
- Make sure the instrument selector is
set to CCD.
Take a test image with Grab to verify
the ST9 is working and the pointing is good.
- If you want to use the Finder
- Initialize the ST-6 CCD mounted
to the orange-colored 5” Celestron telescope that is attacted to the
telescope’s mount. We call this the Finder/Guider CCD. In the ucirob
window, under Finder, click on
the Settings button. Click on
Link. It will initially fail
it cannot set the video head offset, but this is just a software
bug. Click on Link again and
will initialize properly. Set the operating temperature to no
less than 20 degrees C less than the ambient temp and click on Temp Reg. Enter the desired
exposure time (seconds), binning (1x1) and hit Apply. Click on Expose to take a test image.
- Note that if you don’t see the
star in the ST-6 image, it may be that the finder’s FOV is blocked by
the dome. Try moving the dome in 5 or 10 degree increments in the
window to unblock the FOV.
If you need to tweak the
centering of the star in the ST-9 CCD FOV, move the telescope by
entering offsets in RA and DEC in the ucirob window (see the field
and orientations below). If this star was near zenith and you had
to move significantly to get it centered on the ST-9 frame then
you should Reset Home Coordinates in the ucirob window. But don’t
do this if the star is far off zenith because this error may
simply be due to inaccuracies of pointing and slewing.
Sizes and Orientations:
- Mark the ST-9 FOV on the finder
image by clicking on ST-9 Frame
button. To move the telescope so that a certain object in the
guider image is moved to the center of the ST-9 FOV, Right Click on the object so that
the object’s x,y centroid and its photometry will be computed and
displayed and the object will be circled in green on the image. Then
click on Center Object button,
which will move the object to the center of the ST-9 CCD FOV. Take
another test image with the ST-9 CCD to ensure that the move was
If using the finder scope: if you need
to reset the default center of the ST-9 FOV on the ST-6 finder
image then place your cursor on an object in the finder image that
currently lies at the center of the ST9 image, Left Click on the object, which
displays the star’s x,y centroid and hwhm (although hwhm is
incorrect), then click on ST-9 Center.
Turn the ST-9 Frame off and on
to redraw the frame at the new center. Note that the current
default ST-9 center is (x,y) ~ (200, 100).
Once the telescope is centered on
the sky, you might want to check the location of the star in the eye
piece field of view (remember to use the instrument selector in ucirob
to move the flat mirror back and forth between the ccd and eye
piece positions). Also, you can check to see where the star falls
in the field of view of the smaller black-colored finder scope
that’s attached to side of the 24” telescope. If the star isn’t
centered in the FOV then tweak the set screws so that it is. Often
people jog it out of alignment by bumping into it. Note how much
fainter the star appears in this small finder scope compared to the
24”. However this finder can be very useful, because it has the
largest field of view. If the telescope’s pointing is very far off (for
example if you’re trying to point to a planet at very low altitude)
this maybe the most useful finder to use to correctly center the
telescope on your object.
the telescope for the ST9 CCD by pointing to a ~5th mag star
near where you want to take your science images. Set the camera to
the V filter, because when the camera powers up it maybe in the "U"
position which means there is no filter. Take a series of
images of the star at different focus settings and measure the FWHM
and Peak Flux for each to find the best focus, i.e. the focus setting
that gives the smallest FWHM, highest Peak Flux, and the roundest
profile. Find a star bright enough to record > 1000 ADU at peak
in a ~3 sec exposure. Note that you can change filters to
increase/decrease fluxes (all the filters are parfocal). The
minimum time of 3 sec will allow you to sufficiently average over
temporal variations in the seeing caused by the atmospheric
fluctuations. Use a focus step size of ~15 units, and
plan to try 5 to 7 focus values. Step through focus values
monotonically (either always decreasing or increasing) because
there is some backlash in the motors when you change directions,
and hence you want to avoid it. Under Telescope/Change
Focus, enter a new focus value for the T Axis and
click Move. Leave the TUV
axes linked so that all three motors attached to the secondary will
move by the same amount. (You would only unlinks them to change
the collimation of the secondary mirror, but this should only be done
by one of the professors!) Take an image with the ST9 with Grab. Click XHair then left click on the
star. Record the FWHM, flux, and apparent roundness. Repeat for the
series of focus values and determine the best focus. Move the
focus to ~75 units above/below the last used best focus (consult
the CCD Logbook) and then back down/up to the best focus (to mitigate
errors due to backlash). You may have to refocus periodically if the
temperature changes greatly or as you move to different locations
in the sky. As the temp decreases you will have to move to smaller
absolute values of the focus (~10 units/1 deg C decrease in T).
Currently the Best Focus is T = -4376, U = -3143, V = -4526 for the
ST9 CCD for T = 17 deg C when recollimation was last done in
Nov, 2007. Typical values at best focus
FWHM = 3.5 pix.
Next move the telescope to your
science target. In Xephem, if the object appears on the screen you can
right click on it and while
holding down the mouse button scroll to Center + Zoom
then Telescope GoTo.
If the object is not in Xephem's Sky View, you can look up its
coordinates in the Xephem windown by doing Data/Search Memory
and searching for that object then click on Sky Mark and Telescope GoTo
to mark the object on the Sky View and slew the telescope to that
position. You can right click to Center + Zoom
in or out. Take an image to make sure you're target is positioned well
on the CCD.
In not, you can move the telescope using ucirob to center it.
There are two ways to guide
the telescope while exposing on your science target. Using the AO7 +
ST9 Tracking CCD is preferred because the pixel scale of the Finder
Scope + ST6 CCD is very course:
- ST-6 FINDER CCD: North
is Up, East is to the Left with the origin at top,
left-hand cornor of the display. Note that there are two bad pixels
that lie at (x,y) = (221, 168) and (239, 108). Do not confuse them
- ST-9 Science CCD: FOV
= 6.9' x 6.9'. North is Up, East to the Left with the origin at the top,
left-hand cornor of the display.
- ST-9 TrackingCCD: FOV
= 2.6' x 2.2'. North is Up, East to the Left with the origin at the top,
left-hand cornor of the display. The Tracking CCD is located due
South of the Science CCD.
- 40mm EYE PIECE: center
of the ST-9 FOV is approximately one third in radius outward from the
center of the eyepiece FOV roughly along the x-axis
Image & Guide with the AO7 + ST9 Tracking CCD:
Take an image with the Tracking CCD by clicking on Setup,
setting it to the Tracking CCD, then doing Grab. Use a
2-4 sec exposure time. If there is a star in the field that has ~1000
adu at peak then your can use it. If not, move the telescope using
ucirob until you get a bright enough star on the Tracking CCD. To take
your science image, click on AO-SlfG and
Set Exposure =
exposure time (sec) for the science image, Track Time =
the exposure time (sec) for each tracking image, and Track Box = Large
and Dither Exp = No. Hit OK. It will
take a tracking exposure then you will have to left click and drag the
small white box onto the star. Hit Resume. Then
the software will take a series of 8 dark images of the small
tracking box (be patient) then take an image of the box and display it.
It will continue doing so. Watch that the AO7 keeps the star on the
small tracking box. When its done so successfully a few time times,
start your science exposure by hitting Start. Don't
forget to hit Start! The AO settings that we usually use are
SlewRate=500 and Aggressive=10. Note that you can change this if you
like while the tracking exposures are being taken. Also note that
if you change filters you may have to adjust the tracking exposure time
to ensure you have enough counts in the star. One last note, write in
the Observatory Log Book that the science exposure was taken with the
AO7, and it will remind you that you have to take a dark image with the
same exposure time later in the night. Record everything you do in the
Observatory Log Book for the benefit of yourself and others who use the
telescope after you.
Guide with the Finder Scope + ST6 CCD:
Take an image w/ the ST6 to make sure there is one in the field and
define the needed exposure time. The star should have a maximum flux in
the center pixel of a few thousand ADU. In the ucirob window, enter Guiding/AutoGuiding Settings
to open the Autoguiding Parameters window. Set the exposure time and
interval between downloading an image and taking the next image.
Use a minimum of 10 sec as the interval. Hit Apply then click On to take the first image. The
main ucirob window will tell you to left click on the star you want
to use and then hit Select in
the Current Guide Image window. Then it will take repeated images of a
small subregion of the CCD surrounding that star. It will automatically
send small slew movements to the telescope to keep you centered on that
star. Unclick On in the
Autoguiding Parameters window to stop guiding. Remember to turn
off the guider before slewing to a new object.
Shutting Down the Observatory
of the temperature regulation for the ST9 and shut it down (in CCDObs do Setup
then Close Link
edit CCDObs, or in CCDAuto do CCDAuto/Cameras/Imaging
CCD/Turn off temp reg, Close Link then File/Exit).
- If you used the Finder Scope + ST6,
under Finder/Settings turn off temperature regulation.
- Under Power Up turn
off the CCDs.
- In Xephem 's SkyView bring up the Telescope/Configure panel. Click on Running to disconnect link between
Xephem and ucirob. If this is not done, then the next time
the telescope is used Xephem will not be able to send movement
commands to the telescope. If this is was not done the last time
the telescope was shut down, the computer will need to be rebooted
(following the directions below).
- Exit Xephem.
Obs in ucirob.
- Put the grey-colored cap on the baffle.
- Log off the computer and turn off
the monitor, but do not turn off the computer. We leave it on so that
anyone can log in remotely from any unix machine and operate the
- If something goes wrong, call
Profs. Smecker-Hane. Do not leave the telescope/ucirob if you are not
sure the shutter is closed for the night!
If you run into a problem, you can call Profs. Tammy Smecker-Hane
(824-7773 @ work, 509-7195 @ home).
If you need to reboot ucirob:
If ucirob crashes you may need to reboot the machine. You can't
simply reboot the computer because the computer will be sending random
signals to the rack. If you do, you're likely to get random motion of
both the shutter, dome and lights! Instead follow this sequence:
- Turn off the power to the rack
(red button on top of rack) and turn off the power to the AC
controllable outlet box (red button on the middle box in the rack) .
- Reboot the computer.
- Enter ucirob, which will set the
state of the electronic input to the crate. Then exit ucirob.
- Turn the rack and AC controllable
outlet box back on.
- Restart ucirob. Send the dome to
the home position (Observatory/Send Dome
Home) to make sure it is properly initialized.