******************* * Setting Up Kast * ******************* 16 May 2002 - notes from Lacy/deVries/Reuland 18 April 2001 ------------------ A. Assorted Facts ------------------ 1. Get all your useful numbers from: http://herbie.ucolick.org/techdocs/instruments/kast/kast_index.html Some useful quick references. All numbers are a bit rough. pixel scale: 0.8 "/pix (both CCDs) saturation: 25,000 DN (both CCDs) gain: 3.8 e-/DN (both CCDs) read noise: 6 e- (both CCDs) imaging FOV: 145" square = 180 pixels at 0.8 "/pix 2. About slit widths: Typically, you're going to use 1.5" or 2.0" slits for data, depending on the seeing. You don't want slits smaller than the seeing, though of course you're trading resolution when you go to a bigger slit. For standards, use a 5" slit. Here you're giving up resolution in order to make sure that you're collecting all light. Flux-calibrating involves big bins, so you don't really care about your resolution. 3. About the Kast instrument controls. These are bit dangerous, so be careful. (The danger is that you'll change the set-up and think you've changed the instrument...) Here's a peek at the instrument control menu: ----------------------------------------------------------------- Common: Current Setup: 13 Device Status A. Waveplate Unavailable Unavailable Unknown B. Decker open finger Move completed C. Slit 2 arcsec 2arcsec Move completed D. Upper Filter Wheel open open Move completed E. Lower Filter Wheel open open Move completed F. User Filter Wheel open open Move completed G. Beam Splitter d55 d55 Move completed Blue Side: H. Blue Collimator 50000. 49000. Move completed I. Grism 600/4310 452/3306 Move completed J. Blue Filter Tray open open Move completed Red Side: K. Red Collimator 37000. 16000. Move completed L. Grating #6(300/7500) 300/7500 Move completed M. Grating tilt load 14285. Move completed N. Red Filter Wheel open open Move completed R. Set Spectrograph S. Select Setup Z. More... ----------------------------------------------------------------- Note the two columns: "Current" and "Setup". Current shows the actual state of the intrument. To change to the state of the instrument, you make a change in the Setup column then apply the Setup column to the Current column (either as a whole, or one bit at a time). Change something by hitting the relevant letter and then watching the prompt at the bottom of the screen. Here's an example. Let's say you want to change the decker position. Hit "B", then watch for the prompt which appears at bottom of the the screen. Now you've got to know the name of the position you want to go to. For instance, you could type "open" and the SET UP column would change to show the decker in the "open" position. NOTE THAT YOU HAVE DONE NOTHING TO THE INSTRUMENT, you've merely updated the setup menu. You can now apply the entire setup menu to the "current" menu (which shows the actual state of the instrument) with the R key (usually don't initialize; e.g. R then "no"). Or you could apply just the decker status by using a BANG in front of "open". That is: Change decker setup: "B" --> "open" Actually change decker: "B" --> "!open" There are couple of ways to figure out what the available position names are. (1) They're in the Kast manual. (2) In the control window, hit "Z" for alternate screens, then "1" for "configuration". Now hit the letter of the item in whose configuration you're interested. For example: Z --> 1 --> B brings up: Decker Common: # Position Name A. Waveplate 0. 350 open B. Decker 1. 815 2 arcsec C. Slit 2. 940 spect D. Upper Filter Wheel 3. 980 finger E. Lower Filter Wheel 4. 1056 focus F. User Filter Wheel 5. 935 b G. Beam Splitter 6. 680 c 7. 1479 e Blue Side: 8. 1203 f H. Blue Collimator 9. 1056 focus I. Grism +. Next group J. Blue Filter Tray Red Side: $. Availability: Available K. Red Collimator L. Grating M. Grating tilt N. Red Filter Wheel Z. More... Hit Z --> 0 to go back. 4. About the Kast CCD controls. These are not as dangerous. Here's a peek at the CCD control window: ------------------------------------------------------------------------------- Kast blue arm Reticon 400R X 1200C #1 G. Smith __________________________________________CTL: Any Terminal ______________Display CCD 1 (blue)_________________ A. Selection number: 1 N. Menus track display CCD: 1 B. Integ. time: 10 s = 0.17 m R. START C. Obs. Number: 244 S. STOP AND READOUT D. Window: T. ABORT AND THROW AWAY Size (R C) 200 1200 U. PAUSE Origin (R C) 0 0 V. CHANGE INTEG E. Binning (R C) 1 1 W. CHANGE SELECTION F. Obs. type: Normal slow X. COMMENTS G. Recording: Not Recorded ?. HELP H. Display: Blue CCD I. Object: Test J. Selection summary Z. SPECIAL +. Cursor display -. CONTROL L. Wave plate position Unknown *. Run C-shell A Selection number= 1 ------------------------------------------------------------------------------- Change something by hitting the right letter. Watch for the prompt at the bottom, then enter the value you want. Be careful that the blue window is actually controlling the blue CCD (same for the red). More on that below. 5. Miscellaneous commands in the CCD display window: c = plot a column r = plot a row 6. From orthrus, your data directory will probably by /net/shane/data. 7. About the mirror positions. Position 2: Any internal lamps. For us, this just means arc lamps. Position 3: Anything external. For us, this means science frames and dome flats (which are taken with lamps mounted on the secondary ring bouncing off the inside of the dome). ---------------------- B. Instrument Set-Up ---------------------- 1. Start up data taking software. Type "kast" at an xterm to get the spectrograph control window. To get the CCD controllers, on shane desk top select: Data acquisition --> Kast blue Data acquisition --> Kast red This'll bring up a blue window for the blue side CCD control and a red window for the red side CCD control. Be careful -- the red window comes up SET TO CONTROL THE BLUE SIDE. You'll need to change this by hitting a "2" in the red window. (In general, hitting a "1" or a "2" changes the CCD control window from red to blue and blue to red CCD control. This a short cut for the "A" menu option.) 1'. Want to take test frames? Just disable writing to disk with "G". You could also set they obstype to FAST to save time while you're screwing around. It many not be worth, however, as you're likely to forget to change it back; you want "normal slow" for your data. 2. Check spectroscopic windowing. (Make sure you're in a spectroscopic setup! That is, you should be doing all of the following with the slit/grism/grating etc. in the positions in which you'll be observing.) We did this kind of late in the day, with the telescope just pointed to the twilight sky (cover open, obviously). That required the mirror to be in position 3. Take a blue frame and notice that the light is not following in the window. Shift the origin and trim the number of rows until it's nice and centered. Repeat on the red side. Here are the values we found: Blue side windowing Red side windowing ------------------- ------------------ Size (R C) 180 1200 Size (R C) 180 1200 Origin (R C) 10 0 Origin (R C) 105 0 Want to check the windowing earlier in the day? Turn on the arc lamps and put the mirror in position 2. 2'. You might also check out your imaging window, since it's highly vignetted. We didn't bother, since ours isn't an imaging program. 3. Check central wavelength. We're using the D55 (5500 A) dichroic. There's about 200 A of crap on either side, so you want plenty of overlap between the red and the blue. This amounts to making sure your red side lambda coverage gets down to, say, 5300, and your blue side coverage shoots up to, say, 5700. a) Put mirror in position 2. b) Turn on both arc lamps. c) Due red side first (blue is warming up): t = 60s. d) Due blue side: t = 120s. 4. Focus loop on arc lamps. Tackle red side first. (Focus loop amounts to sliding the collimator in steps of 5000; use option K in the control window.) You are shooting for a FWHM of about 2.3 pix on the red side. a) Go to some starting value. (We had an old best focus of 36000, so we shot down 4 steps below that to 16000.) b) Take 15s exposure. c) Check FWHM. This is easiest done in IRAF. You can also estimate it by zooming in on lines in the Dtake window. d) Pass through your focus minimum in steps of 5000, shooting for FWHM = 2.3. Here's our focus loop from 16 May 2002: red collimator FWHM frame ---------- ---- ----- 16000 4.1 117 21000 3.3 118 26000 2.45 119 31000 2.07 120 36000 2.09 121 41000 2.31 122 ----> 33000 2.06 123 <---- BEST VALUE 5. Focus loop on blue side. Same algorithm as above, 'cept the best value won't be as good. Shoot for 2.4 pix or so... Here's our loop: blue collimator FWHM frame ---------- ---- ----- 25000 3.6 124 30000 3.0 125 35000 2.7 126 40000 2.5 127 ----> 45000 2.4 128 <---- BEST VALUE 50000 2.6 129 6. Save your setups. We want only this one choice of dichroic/grism/grating, so once we have the collimator values, we can save that setup and just flip back to it all night. Here it is: Common: Current Setup: 13 Device Status A. Waveplate Unavailable Unavailable Unknown B. Decker finger finger Move completed C. Slit 2 arcsec 2 arcsec Move completed D. Upper Filter Wheel open open Move completed E. Lower Filter Wheel open open Move completed F. User Filter Wheel open open Move completed G. Beam Splitter d55 d55 Move completed Blue Side: H. Blue Collimator 45000. 45000. Move completed I. Grism 452/3306 452/3306 Move completed J. Blue Filter Tray open open Move completed Red Side: K. Red Collimator 33000. 33000. Move completed L. Grating #6(300/7500) #6(300/7500) Move completed M. Grating tilt 14285. 14285. Move completed N. Red Filter Wheel open open Move completed R. Set Spectrograph S. Select Setup Z. More... Don't worry that the decker is in "finger" mode. This is so that the N.A. can center objects on the slit; it doesn't get in the way of the slit. ----------------------------- C. Observing Order of Events ----------------------------- Your master order of events is going to be something like: a) Afternoon / twilight calibrations. b) Standard star. c) Set up on target. d) Observe target (can have different red/blue exposure times). e) Turn off guiding; rotate dome; turn on flatfield lamps. f) Take arc lamps then dome flats. g) Next target... h) Morning standard / calibrations. Now for more details. In reality, we got a late start on 16 May 2002, so we jumped right from checking the windowing and collimator focus to taking data. This was probably not ideal. 1. Could do some dome flats and darks in the afternoon. See later in the notes for the details. 2. Night assistant goes to pointing star and focuses the TV. The TV guide camera is just looking at the back side of the slit, illuminated by the sky. Hence, it's parfocal with the slit. When the night assistant focues the TV, that amounts to focusing the telescope; you don't need to do it as a separate step. You might take a quick spectrum here so that you can see where light from a star that you think is centered on the slit falls on the CCD. We found: y-pix of trace blue side 89.5 red side 90.8 2'. If you're going to do a blind offset, you might do an offset test right around now. That is, offset, then offset back and see if you wind up in the same place. 3. Hit a standard. A standard will be bright enough to see on the TV, so the night assistant can put it on the slit (and maybe even guide -- if you cared -- off the spillage.) Remember to make the slit width extra wide. We actually ended up using 6". I integrated for around 3 minutes or so. Find standards at: http://herbie.ucolick.org/techdocs/standards/Stds_Stone.html 4. Go to a science target. I'll describe target acquisition for a faint object. If you have a target which is bright enough to see on the guide camera, well then just fuckin' set up on it and take your data. I'm going to presume that you have a set-up star, and that that star is bright enough to see on the guide TV. I'm also going to assume that you have some preferred PA for the slit, like you're going after two targets or something. a) Go to set-up star. Have night assistant center it on the slit. b) Rotate the slit to the desired position angle. c) Make your blind offset to the target. You're going to do this yourself in the CCD control window. (i) Bring up the telescope control window with Z --> 5. (ii) Hit "T" for move telescope. (iii) Select "b" (presumably) for seconds of arc, NOT seconds of time. (iv) Enter RA shift. (v) Enter Dec shift. (vi) The 'scope'll move when you hit return after the Dec shift. (vii) Go back to the CCD control screen with ESC. d) The night assistant will look around for a guide star. While he's doing that, you can start your integration. e) After your first integration reads out, you're going to want to dither along the slit. Again: (i) Bring up the telescope control window with Z --> 5. (ii) The *first* time you do this, you'll need to set the dither amount with "A" and "B". We used: A. Position No. 1 (r,c) = 0 0 B. Position No. 2 (r,c) = 10 0 (iii) Now actually make the move with "C". Before you do that, though, have the night assistant go off guiding, then have him reaquire the guide star. f) Repeat until you're satisfied, then do your calibrations... 5. Calibrate your science target. There is some flexure in the CCD if you slew all about, so it behooves you (to some extent) to due your calibrations right after your science target, before slewing to your next science target. Here's a nice, time-saving algorithm: a) Turn on all lamps: arc lamps, super blue, and CCD flat field lamp. b) Put the mirror in position 2 so that you're looking at the arc lamps. Due 60s on the red side, then 120s on the blue side. (The blue is slow to warm up, so really do red first.) c) Switch off the arc lamps. ** Meanwhile, the NA has been rotating the dome into the FOV of the ** telescope. When he/she/it comes back, you can do dome flats. d) Put the mirror in position 3 so that you're looking at the flat field lamps. e) The super blue is really bright -- it will saturate the red side in 1 s. So do your blue dome flat with BOTH lights on. Do it first, for 10s. (Get 4 or 5 of these.) f) Now switch off the super blue and do the red side dome flat with just the CCD flat field lamp on: t = 10s should work. Get 4 or 5 of these. 6. At some point, you might want to take an image of the field. You know, to see if you were pointed in the right place and all. Here's the imaging mode we used: Common: Current Setup: 15 Device Status A. Waveplate Unavailable Unavailable Unknown B. Decker open open Move completed C. Slit open open Move completed D. Upper Filter Wheel open open Move completed E. Lower Filter Wheel open open Move completed F. User Filter Wheel open open Move completed G. Beam Splitter out out Move completed Blue Side: H. Blue Collimator 45000. 45000. Move completed I. Grism 452/3306 452/3306 Move completed J. Blue Filter Tray open open Move completed Red Side: K. Red Collimator 18000. 18000. Move completed L. Grating mirror mirror Move completed M. Grating tilt 19000. 19000. Move completed N. Red Filter Wheel open open Move completed R. Set Spectrograph S. Select Setup Z. More... 7. Science science science, then hit a standard. 8. Do some twi's. 9. Bias frames. I like to take biases, even though Kast supposedly does a bias subtraction as it reads out. To take a bias: a) Set the integration time to 1s. That's as short as it goes. b) Set the observation time to Dark. Don't know exactly what that does. c) Do a bunch. I couldn't figure out a way to automate a loop, so I did about 10 per side by hand. 10. Darks. Just to see if there was any dark current, I took a science-length exposure, in the manner of the fussy British. Again: a) Set the integration time to 1800s. That was my science integration time. b) Set the observation time to Dark. Don't know exactly what that does. c) Do one, maybe two. You won't want to stick around, right?