Observing Environment

You are now at the 4m observing room. Although the first two computers listed below are the ones that actually control the instrument, they should be hidden from you. We access them through virtual "VNC" windows (see "Starting VNC"), which we can run from any computer, although you are likely to run them from either ctiozm, ctioa7, or both. The benefit of doing things this way is that it allows us to see what you are doing from La Serena, and could even be used to allow collaborators to check up on you from their home institutions--please talk to us first if you would like to do this, however.

  • ctioa6: A Linux PC running the Hydra software and VNC server. Your assignment files will need to be copied to this computer. Log in through ssh as "hydra", and put your assignment files in a subdirectory of "/home/hydra/fields".
  • ctioa1: Sparc10/Hypersparc, SunOS 4.1.4, 128 Mb RAM, CTIO 4.0m A Sun OS workstation running the ARCON CCD controller VNC server. Your images will be stored on this computer. You can access the disks by automounting /ua1?.
  • ctiozm: Dual 2.8GHz Intel, Linux, 2 Gb RAM, CTIO 4.0m. We use this computer to run the Hydra VNC windows and is your best choice for on-the-fly data reduction. Login with the "hydra" username, and try not change any of the setup files such as .cshrc, .login, README, etc.
  • ctioa7: Ultra2/Dual 200Mhz, Solaris 5.5.1, 512 Mb RAM, CTIO 4.0m A Sun Solaris workstation for data reduction. Can also be used to run any of Hydra's VNC windows.

Generally one person will be the observer and operate the VNC windows. The other person will be doing assignments, bookkeeping, and totally useless web surfing (when the observer is not looking).

All the computers are auto-mounted and can see common disks. Thus, if the ctiozm or ctioa7 user has made an assignment file on the ctioa7 disk, this can be copied directly to a local disk on ctioa6. The only weirdness is that the ctioa6 disks cannot be seen by other users via automount. They can be accessed by scp, though. ctioa6 can see the disks of ctioa1, ctiozm, and ctioa7.

Logging into the computers:

The computers should be set up for you. If not, here is what you do. Log into ctiozm, username "hydra". Then type "startx" to bring up the window manager.

==> After clicking on the Hydra GUI button located along the bottom panel on ctiozm, which brings up the VNC window, type "hydractio" in one of the black NTERM windows. There is no need to source it into background (with the "&"). The Hydra GUI will come up. It will ask you if you want to reload the previous coords. Unless you left the Hydra program with the fibers at a configuration position and want to continue to use this setup, answer this "NO." You will now be told to type "coldstart" in the white Hydra control window. Hydra is now ready for use.

TO LEAVE the program:

Under file, use QUIT.

  1. Do you really want to exit the application? YES
  2. Do you want to move the fibers to the transport position? NO (note, though, if you have used a different concentricity file, you really need to stow the fibers first -in this case, answer YES.)
  3. Do you want to turn off the drives? At this time, TURN OFF the drives. At present, we have found that the motors can burn out if left on, so the drives must be turned off.

==> Bring up the Arcon VNC window on ctiozm:

If it's not already running, right-click to bring up the menu and click on "(Re)Start Arcon". At this point it takes about 60sec for a dizzyingly large number of designer colored windows with mini-fonts to open. You will be asked a single question half-way through the process "Do you want to synchronize the parameters?" In the 6 years I have been using ARCON, I have always said "yes." I have no idea what happens if you say "no," but it probably involves pain and shouting. I think the question is there to see if you are awake.

I HATE the default fonts for the IRAF window. I edit the following line into IRAF section of the .openwin-menu:

"IRAF"     DEFAULT exec  /local/combin/xgterm  
    -title "IRAF" \
    -geometry 80x40 \
    -bg mistyrose\  
    -fg blac \
    -sl 600\  
    -cr darkred\  
    +sb  \    
    -fn 10x20\  
    -e cl  


==> You will probably want to run the Hydra simulator on ctiozm or ctioa7. If the latest version is not already installed, the user should immediately install the "hydrasim" software using the instructions at the hydra software page

Load your coord and assignment files in some subdirectory in ctiozm or ctioa7 - I use "fields." Try entering one of your files into the simulator software to make sure everything is working.



    slit 141    
  | --------------------------------------- |  
  |   |  
red |   | blue
  |   |  
  |   |  
  | --------------------------------------- |  
     slit 0    

cl> ccdinfo

(gain = 1) Gain setting
(xsum = 1) pixels summed in spatial direction
(ysum = 1) lines summed in spectral direction
(xstart = 1) Start of ROI in X (in unbinned pixels)
(ystart = 1) Start of ROI in Y (in unbinned pixels)
(xsize = 2048) Size of ROI in X (in unbinned pixels)
(ysize = 4096) Size of ROI in Y (in unbinned pixels)
(extend = "separate") Method of extending ROI to include overscan
(noverscan = 64) Number of overscan pixels (binned)
(xskip1 = 10) X pixels to skip at start of overscan (binned)
(xskip2 = 0) X pixels to skip at end of overscan (binned)
(xtrim1 = 0) pixels to trim at start of data
(xtrim2 = 0) X pixels to trim at end of data
(ytrim1 = 0) Y pixels to trim at start of data
(ytrim2 = 0) Y pixels to trim at end of data
(preflash = 0.) Preflash time (seconds)
(pixsize = 15.) Pixel size in microns
(nxpixels = 2048) Detector size in X
(nypixels = 4096) Detector size in Y
(detname = "SITe4096") Detector identification
(mode = "ql")  


        *** Table of gain values***
SITe 2Kx4K + Arcon3.7
           Hydra Bench Spectrograph      

   Read Times
  - ---- - ------------------------------------------------
1: 1 3000 3   2.36 5.2 60000 5.0 101 85 61
2: 2 8400 3   0.84 3.0 15000? 0.25 150 133 85

Spurious Charge is signal per pixel generated by clocking
the CCD. Read Noise is quoted for overscan pixels. In the image:

Noise floor = sqrt{ Read_Noise^2 + xbin * ybin *
              (Spurious_Charge + Dark_Current * Exposure_Time) }

Dark current = 0.7 e-/hr (per unbinned pixel) in Jun, 2001,
               at CCD_TEMP= 150K (pumped N2, heater off)

For gain 2, bin 2x2, total noise in 1800 sec dark = 3.5 e-

Read times are quoted for binning (spatial x spectral).
When binning 2x2 the ADC saturates before full well is reached.

NB: A peculiarity of this CCD is that full well is highly
    variable from pixel to pixel causing vertical trails to
    to appear at high signal levels. The full well figures are
    very preliminary estimates for the worst pixels.

*** Select gain setting from the first column

*** The current gain setting is 1


Updated on April 15, 2024, 5:09 am