Fick Observing Manual for Newtonian CCD Imaging
by Guillermo Gonzalez and Joe Eitter
(August 2002)
Setup instructions:
Steps 1 to 12 can be done before it gets dark enough to observe.
1) Upon arrival turn on the air conditioning/heating as the case may be.
In the summer the control room should be about 78º F; in the winter
set it to 68º F. You may want to open the covers on the
windows.
2) Turn on the monitor that displays the video camera aimed at the South
wall arrows. Open the South wall; stop when the arrows match. Then, open
the roof. Stop when the roof and North wall are nearly flush. Do not
trust the limit switches for the roof and wall! Turn off the video
monitor when finished opening up.
(Note: This is a good position to leave the slide selector in when not in
use.)
3) Go out to the telescope and remove the cover just inside the Newtonian
port. Open the mirror covers. Uncover the two finder scopes if needed. If
the black cloth is on the Newtonian port optics, remove.
4) Turn on the power switch on the power strip by the East side of the
pier. Turn on the coolant fluid pump if necessary. Turn on the Andor
CCD power supply on the floor near the North side of the pier.
5) Plug in the STV all-sky camera power cord and uncover the camera.
Turn on the power to the telescope video camera (by the North wall). Plug
in the dome lights using the "dome lights - flat lamps" power
cord.
6) Make certain all the ladders and power cords are positioned to allow for
free motion of the telescope.
7) Back in the observing room, we need to start turning on the equipment
that takes the longest time to reach operating status. In order, these are
the Andor, ST5, and STV CCD coolers. We will do quick
starts of these units and return to them later to finish the setups. First,
power up the Andor CCD controller computer. Start the Andor
software. Turn on the camera cooling by clicking on the box on the lower
right of the window. Set the temperature to -70º C.
8) Power up the ST5 autoguider control computer and monitor. Type
“ccd” to start the ST5 controller software. Under the
“camera” menu, select “setup”. Set the temperature to
about -25º C below the dome air temperature. Note the cooling current.
If it gets above 99% you might have to increase the temperature.
9) On the left side of the control room power up the P5-166 PC on the rack.
This runs the Guide 8.0 star-charting program and controls the
STV all-sky camera. Start the STV software. Set the cooling
to the STV using the "setup" and "parameter"
buttons. The STV can be cooled to about -15º C below the dome
air temperature. Note the cooling current. If it gets above 99% you might
have to increase the temperature. Start the Guide 8.0 software.
10) Turn on the power to the Newtonian control console above the P5-166 PC
monitor. This unit reads three telescope temperatures (*-1.0ºF),
controls the positions of the xyz (focus-RA-Dec) translator of the
ST5 autoguider and the dark slide at the input to the Newtonian
port. Open the dark slide with the toggle switch (hold for about 15 seconds
until the light goes from yellow to green).
11) Now on to the DFM console. Make certain the telescope drive
power switches are off. Turn on the main telescope power. Turn on the
DFM computer immediately below the DFM console. Then, turn on
the three switches on the lower left of the console. Make sure the
"object-list - The Sky" switch is in the "object-
list" position and the "East - West" switch should be in the
"East" position.
12) Power up the "object lists" computer above the DFM
console. Start DOS and then type ‘sxz’.This will list
bright stars near the zenith. One of these stars can be highlighted and the
"s" key will transfer the coordinates to the DFM
computer.
Once it gets dark,
13) Turn on the video monitor for the telescope monitoring camera.
14) Turn on the STV all-sky camera display monitor (settings
described below).
15) Click “Image” in the STV software to start
acquisition. The software will first acquire a dark frame, and then it will
start acquiring images continuously.
16) Close the window blind in the observing room.
17) Check to see if the Andor CCD temperature has reached -70º
C.
You are now ready to observe!
Shutting down:
Generally, work backwards from the above procedure. The most important
tasks are the following: 1) turn off the Andor CCD cooling, 2),
turn off the ST5 autoguider CCD cooling, 3) move the telescope to
the stowed position, 4) turn off the telescope drives, 5) cover the
all-sky camera and Newtonian port, close the telescope covers, cover
finders, cover STV all-sky camera 6) close roof, 7) close South
wall, (make sure the hand levers for the dome control are NOT left in
either the "South Wall" or "Roof" positions) 8) turn
off powered items around the telescope, 9) turn off all computers, DFM
console main power, and monitors. Note, the Andor CCD control
software will not let you close it down until the CCD head has warmed
above a certain value. Then, the temperature will read "Off".
The cooling current of the ST5 autoguider should be zero before
turning off the power at the telescope or ending the ST5
program.
Additional observing details:
Summer versus winter observing:
In the summer the roof and walls will move faster than in winter. Do not
trust the limit switches on either the roof or wall! The Andor
CCD will require additional air cooled water when the air temperature is
above ~55-60º F. When it is below ~-5º C in winter the
Andor program cannot be ended normally because the CCD
temperature will not get above 0º C. After the cooling current has
been off for at least five minutes, you can end the program by doing
"Ctrl-Alt-Del". In summer make sure to turn off the air
conditioner when leaving. In winter set the heat to 62º F. If the
outside temperature is going to be below 20º F or above 80º F
place the covers on the windows.
Saving data:
Presently, we save Andor CCD images to 100 Mbyte Zip or CD-R
disks. Check the size of your data folder first to make sure it will fit
onto your disk. If you have lots of data to save on a CD-R disk, start
saving when to turn off the CCD cooling. Don't forget to save a test
image in "signed 16 bit fit" format before starting to store
images at the start of the night.
Taking all-sky images with the STV camera:
After the sky is dark, the "Image" and "Parameter"
buttons in the STV window can be used to set the image
parameters. Set exposure (= 10 to 30 seconds), gain (= 1x), dark
subtraction (= yes), mode (= continuous), sample time (= 1); the values
are set with the “Value” button. After the image is displayed
the "Brightness" and "Contrast" can be adjusted.
DFM pointing computer operation:
1) Zero the telescope coordinates:
First, Select’ a bright star near the zenith with the object lists
computer and press return. The coordinates should automatically feed
into the pointing computer; check that they appear on the ‘next
object’ line. Type either ‘8’ (Go) or hit the
‘Go’ button on the DFM console. Take an image with the
Andor CCD (make sure the Newtonian slide is open; the V or R
filters will give more signal). If the bright star is not in the center
of the frame, then estimate how far you need to move the telescope by
calculating the number of pixels between the star and the center of the
frame (one pixel is about one second of arc). You can use the ‘set
offset’ command under the ‘movement’ menu to move the
telescope a small amount. After the star is centered and focused in the
CCD frame, you can 'zero' the telescope coordinates. Type ‘1’
to enter the initialization menu, then ‘2’ (‘set
telescope position”); hit ‘return’ to zero the
coordinates. If the star is completely off the CCD, you will have to use
the finder scopes to center the star, then do the above.
2) To move the telescope to a new target, use the “movement
menu”. You can use the Messier object library in the pointing
computer with option “3” (“select library object”
[for M5 type 5]), or type in the coordinates with option “1”
(“set slew position”), or feed in coordinates from the object
lists computer (using the “ngc” catalog, for example).
3) To take a lamp flat or stow the telescope, go the “miscellaneous
menu” and type “5” (“set flat position”) or
"6" ("set stow position"). Note: Don't forget to
turn off track on the DFM console. Go out to the telescope and
plug in the flat lamp power. Make sure the black cloth is wrapped around
the Newtonian focus box and the flat target is in the 'normal position'
with the South wall in the up position.
The switch for the "dome lamps - flat lamps" is to the lower
right on the roof/wall control console. A second smaller switch on this
box, when in the down position reduces the power to the lamps. Use this
switch only when doing the R and I flats. The rest of the time it should
be in the up position.
Using the ST5 autoguider:
1) To setup the autoguider, go the “Track” menu and select
“Track” (or type 't', 'r'). The software first obtains a dark
frame, so it instructs you to close the Newtonian slide and then open it
when the dark image has been acquired. This dark frame will
automatically be subtracted from each ST5 image obtained for the
remainder of the night, so long as you do not change the exposure time.
Your star should appear in the frame. If not, your RA and DEC offsets
were not correct. Once you have the star in the autoguider field, adjust
the focus with the autoguider focus (not the main telescope focus!)
until the image is round (use the focus chart on the DFM console
for the ST5); note, you need to focus the telescope for the
Andor CCD first. To acquire a new image without starting the
autoguiding, hit the “esc” key. Note: the focus for the Andor
CCD will be different for different filters (see below). This will also
require the focus of the ST5 to be adjusted for different
filters. As the RA - Dec position of the autoguider is changed, there
might need to be a small adjustment in the focus of the autoguider.
2) If you are confident that the pointing is accurate and you know the
RA and DEC offsets errors between the centers of the autoguider
ST5 and the Andor CCD fields, you can use the autoguider
to guide on a 9th or 10th magnitude star in the
same CCD field as your science target. You can use the Guide 8.0
software to find such a star (you can convert it to a red screen with
“Alt-R”). The number “10” field is approximately the
size of the Andor CCD field (18' square). You can get the offset
between the center of the field and the guide star by clicking on the
center object with the right mouse button depressed and dragging to the
desired guide star. Then, set the displayed RA and DEC offsets on the
autoguider (and applying the appropriate offset errors, if any).
3) To start the autoguider, go to the “Track” menu and select
“Track”. Once the image comes up, adjust the cursor position
to overly the part of the star image with the maximum counts; note, it
might not be the center of the star image. Then, hit the return key
twice. Watch the first few centering residuals to make sure the software
does not lose the star. Once you are satisfied that the guiding is
working, you can start your Andor CCD exposure. If you have
guiding problems make sure the balance of the telescope is correct.
Clouds are the most frequent cause of the autoguider to lose its
star.
Filters and focusing:
Filters: The filters for the Andor CCD are selected using small
while box just to the left of the Andor control PC monitor.When a
switch is in the ‘down’ position, the wheel will stop at that
position. When it is in the ‘up’ position, the wheel will pass
by that position. To save time changing filters, only set those switches
in the down position that correspond to the filters you are using. To
start the filter wheel moving, press the red button for about one
second.
Focusing: The focus for the Andor CCD is controlled
with the hand paddle just to the left of the Andor control PC
keyboard. The two top buttons control the focus. The focus encoder value
is displayed in red LEDS on the small box just to the right of the
DFM console (one unit of focus change corresponds to 0.0011
inches). Notice that the focus value is different for each filter. The
relative offsets are listed on a small paper just to the left of the
Andor control PC monitor. The focus also varies with hour angle
and telescope temperature. If you want to keep the images centered using
a set of filters, you will need to move the telescope for the different
filters. If you change the focus by -32 units move the telescope by
2x-32" = -64" (64 arc seconds to the west). Note also that the
Newtonian focus suffers from astigmatism, resulting in oblong star
shapes when not in optimum focus.
Using Andor software:
There are two ways to acquire images with the Andor CCD control software: 1) with the green button on the upper left of the screen, or
2) with a program. The first method is quick and useful when setting up
the telescope at the start of a night. The second method writes more
info in the image header. The first time you save an image be sure to
set the type to “16 bit fits signed”. From then on all the
saved images will be of the same type. The images are read out at a rate
of 16 _sec per pixel (about 17 sec. for a full unbinned 1024x1024
image). Before saving your first file, make a new folder within the
Andor folder and label it “mm-dd-yy” according to the
UT date.
There are three programs that you will find useful: CCDS.pmg (for
acquiring individual science target images), BiasA.pmg (for acquiring
two bias images), and CCDM.pgm (for acquiring multiple images [also
dark frames]). You must update the filename and exposure time before
running a program (see example below). These programs save images
without prompting the user. The programs are kept in the Andor\mm-dd-yy
directory. The CCDS program is shown below.
You might also find it useful to use the command line to set the
displayed range of grey levels. For example,
“scaledata(#0,500,2000)” would set the lower and upper values
to 500 and 2000 respectively. You can also adjust grey levels with the
bar above the image display box, but it is somewhat tedious. The image
display can be magnified or demagnified with the buttons to the lower
left of the image display. To get a better view of previously acquired
images, you can also open the AVIS FITS viewer software,
available on the same PC. When the programs are used a text window is
written showing information about the image taken. This can be stored
in the same directory as the data. The name used is of the form
“mm-dd-yy.txt”. Don't forget to store this file after taking
the final image.
