2.7-m telescope coudé spectrometer (cs2n-TK3)

Personal Reference Notes

Prepared by Tom Barnes

(last updated by TGB August 24, 2004/last web update May 3, 2006 MF)

Coude' Observers Page

McDonald Observatory Online Manuals

See Carlos Allende Prieto's coude' resources

Basic Facts Test Operation Night report (xreport)
Request for Services Spectrum Display Window Starting the Night
First Afternoon Setup Orientation of the Image Focus the Telescope onto the slit
Bringing up IRAF & ICE Setting the Wavelength Region Ending the Night
Spectrometer Focus Sending tar files home
Making a flat field Writing IRAF files to tape
Taking a Th-Ar Exposure Sun stuff
Taking a day sky exposure Instrumental Point Spread Function (PSF)
Telescope Control System (TCS)

Note: Use your own computer account rather than the "tgb" account wherever it appears.

Basic Facts


Request for Services

First afternoon set-up

Go here if you are using IRAF for the first time (or if you need to remake it).

Bringing up IRAF and ICE cs2 telescope interface TK3 detector interface TK3 controller interface cs2 instrument interface cs2 observing interface
  • Parameters that are set manually are 'rootname' and 'sequence' (for specifying the filename), `pixtype', 'observers', and 'commands'. N.B.: 'pixtype' must be set to match 'detpix' in detpars. The string shown below for 'commands' causes the image to be displayed at the end of readout on a display tool (ximtool or SAOimage). The display tool must be running at the end of the readout.
  •  ic> epar obspars (to set up the observing task) Test operation Spectrum display window Orientation of the image Setting the wavelength region Spectrometer focus Making a flat field Taking a Th-Ar exposure Taking a day sky exposure Telescope Control System (TCS) See the TCS manual for more information.

    See the apogee guider manual for information on setting up the guider.

    Night report (xreport)

  • In an Oberon window,
  • A night report window will be created. Fill in the appropriate fields.
  • Save the xreport periodically.
  • At end of the night, quit it to file it.

    Starting the night

    Focus the telescope onto the slit Ending the night Sending tar.Z files to your home computer
    • It is quick and efficient to send tar.Z files over the Internet to your home computer. However, the process does take some preparation. Within an IRAF window on Oberon, if the files are in .imh, .pix format, do the following
      •  cl> cd /data1/oberon/tgb/<data directory>
      •  cl> !files *.imh > imhlist (to create a file listing all the .imh files in the current directory)
      •  cl> !sed s/imh/fits/g imhlist > fitslist (to change the .imh to .fits on each file name and store the new list in file fitslist.
      • cl> unlearn wfits   (to get rid of the "yes" or "no" in the "newtape" parameter)
      • cl> epar wfits
        •  "iraf_file = @imhlist"
        •  "fits_file=@fitslist"
        •  "newtape= (blank)"
      • cl> wfits    (to create a fits file for every IRAF file and retain the same name)
      • If the files are .fits to start with, begin the process here.
        • cl> !/opt/local/gnu/bin/tar cvf /data1/oberon/tgb/nite1/nite1.tar nite1/*.fits     (to create a file nite1.tar containing the *.fits files inside a directory /nite1)
        • cl> !compress nite1.tar (to create a compressed file 'nite1.tar.Z' of the tar file)
        • cl> !scp nite1.tar tgb@astro:/tgb/tgb/<datadirectory> (to transfer the file to /tgb)
        • tgb@astro's password: <password>.
        • nite1.tar.Z      (line showing progress of the transfer)
      • It took 22 minutes to transfer 286 Mb at 1800 CST.
      • It took 15 minutes to transfer 205 Mb at 0300 CST.
      • At home, the data may be decompressed and extracted,
        •  astro> decompress nite1.tar.Z (to decompress the file)
        •  astro> tar xvf nite1.tar     (to extract the *.fits files from the tar file)
      • The above format for creating the .tar file will lead to the extraction creating a directory "nite1" into which the *.fits files are put.
    Writing IRAF files to Exabyte tape
    • Data may be written on exabyte tapes (2292 Mbyte) in FITS format, ~130 full-sized frames. However, it is inefficient to put that many .fits files on a tape as the time to skip ~100 files is nearly two hours! It is better to put only a few files on each tape.
    • The IRAF names for the tape drives are listed on a posting just above the rightmost computer monitor as well as here . Oberon is connected to mtbc (hi density, 10 Gb) and mtbb (lo density, 2.3 Gb). It is recommended that one use the lo density drive, unless you are sure you have a high density drive at home to read your tapes. High and low density tape writes may not be put on the same tape. Once a tape has been used for either high or low density tape dumps, the tape must be completely erased (not just removing the data) before you can use it for the other density.
    • If the files are in .imh, .pix (IRAF) format:
      • To start the tape dump, in the data reduction window,
        •  cl> cd /data1/oberon/tgb/nite1         (to go to data sub-directory)
        •  cl> dir         (to verify location and presence of .imh, .pix files)
      • Load the Exabyte tape in the drive
        •  cl.> allocate mtbb    (to assign lo-density drive to Oberon)
        •  cl > dataio - (to launch data I/O package)
        •  da > epar wfits (to verify parameters in write package)
          •   change only the first three parameters as appropriate
          •   "iraf_fil= tgb*.imh" or @filename (a list of files to be copied)
          •   "fits_fil= mtbb" (to send the files to tape)
          •   "newtape= yes" or "no"
          •   control-d to escape editor or :go to launch wfits directly
        •  da > wfits (to launch wfits if :go had not been used, do a return for each query)
        •  da > deallocate mtbb   (to rewind tape after finished)
      • Eject the tape
    • If the files are in .fits format:
      • It is vastly faster to write tar files to Exabyte than to write FITS files directly. It takes about 65 seconds to add one .fits file to a tar file on the tape. A lo density exabyte tape (2292 Mbytes) holds ~130 full-sized frames.
      • The UNIX names for the tape drives are listed on a posting just above the rightmost computer monitor as well as here . Oberon is connected to rst13 (hi density) and rst4 (lo density). It is recommended that one use the lo density drive. Changing rst13 to nrst13 (etc) will cause the tape to rewind after the end of data.
      • Load the Exabyte tape in the drive rst4 (=mtbb)
      • From within an Oberon window,
        •  % tar cvf /dev/rst13 *.fits to write all the FITS files in the current directory to a tar file on the tape.
        • %mt -f /dev/rst4 rewind to rewind the tape
        •  % mt -f /dev/rst13 status to check on what the tape is doing
        •  % mt -f /dev/rst13 fsf N to skip N files
        •  % tar vf /dev/rst13 > tapelist.txt to list the tape into a file tapelist.txt
        •  % type tapelist.txt    to list on the screen the contents of tapelist.txt
      • At home, the tape may be read using
    •  % tar xvf /dev/rstN where rstN is the local /dev
    SUN stuff
    • Mouse control:
    • To cut and paste, select text with the left mouse button and paste it at the cursor location with the  right one.
    • Middle mouse button grabs and moves things.
    • Use the up/down arrows to move to earlier typed lines.

    Instrumental Point Spread Function (PSF)

  • The instrument does spread the light in the dispersion direction (by the echelle) and in the cross-dispersion direction (by the prisms). The shape of one Th-Ar emission lines shows how light is spread.
  • PSF in cross-dispersion direction:

    1. Put the pinhole in the slit (#13). The pinhole is 300 micron in diameter and represents short slit in the cross-dispersion direction.
    2. Make an integration of an arc spectrum.
    3. Display the frame on ximtool, and type "imexam"
    4. Zoom in on an isolated emission line.
    5. Place the cursor on this line.
    6. Push "e". A graphical window will pop-up and display a contour plot.
    7. If the scale of the contour plot is inconvenient then go out of "imexam" by typing "q"
    8. In the IRAF window type: epar eimexam and change those parameters which you want to change. Go out of eimexam by typing "Cntrl D"
    9. Go into imexam and repeat 3... 9 till you are happy.
  • PSF in dispersion direction:
    1. Put slit #1 in the slit holder. This slit is longer (3.5mm) then the diameter of the pinhole (3.0mm) and therefore less suitable to look at the cross-dispersion PSF. The width (90micron=0.09mm) is however much smaller then the diameter of the pinhole. Therefore this slit is very useful to examine the dispersion PSF.
    2. Go through points 2-9 above.