DBS Quickstart Observing Guide

Beginning Your Run

  • IMPORTANT: Be familiar with the SSO and 2·3m rules.
  • Fill the dewars every morning and evening. The dewars typically have a 12 hour hold time. Check the CCD log book for appropriate times and always fill in the CCD log yourself. Remember there may be dewars on the telescope other than the DBS, e.g., the Imager, that need to be kept cold for the next Observer. Check with technical staff.
  • The DBS Blue and Red have new heads, mounted in the 2nd half of 2005. Contact Technical Staff for updates on their status.
  • TAKE BIAS FRAMES AND DOME FLATS IN THE AFTERNOON to check that the system is working, so that if you have any trouble, the technical staff will be on hand to help. You should plan to start setting up for your nights observing in the afternoon before observing at a bare minimum. This will allow you to contact the technical staff to help you before they leave for the day.

    • Changing DBS Hardware

  • Ensure you have the correct dichroic installed. (Changing Dichroics)
    • The DBS must be at vertical park before removing or changing the dichroic.

  • Ensure you have the correct gratings installed. (Changing Gratings)
    • The DBS must be at horizontal park before removing or changing the grating.

  • Set the required grating angle. The controls for grating angle are above and below the spectrograph and can be awkward to reach. Release the smaller grating lock before attempting to change the grating angle. Securely engage the grating lock afterwards, but do not over-tighten.
  • Focus the spectrograph collimators. This is most easily done on an arc spectrum. The focus dials are similar to the grating angle dials. Release the lock before moving the focus and gently secure it again afterwards.

    Login as yourself at console ("mouldy" for DBS red, "mallorn" from "moist" for DBS Blue), start cicada and run `teldisk' from the `Utilities' menu to clean up data area and create your own subdirectory. Data will be stored in this subdirectory (called e.g. "/data/mouldy/cicada/jsmith" for the user jsmith using the DBS Red running on "mouldy".

    Start Of The Night

    Start telescope:

  • At main console, press buttons CONSOLE ON and TELESCOPE SYSTEMS ON.
    If the SERVO FAULT lamp is lit, press OFF and then SERVO FAULT/RESET to attempt to clear it. If the BUILDING DRIVE FAULT lamp is lit, press TELESCOPE SYSTEMS OFF, BUILDING DRIVE RESET and then TELESCOPE SYSTEMS ON. If this does not clear the fault(s), continue startup anyway, and later run the DIAGNOSE program to gain further information.
  • The telescope control computer is called MAIA.
  • To log on, press BREAK at the telescope control keyboard.
    Username is TELESCOPE.
    For password, see the technical staff.
    Unless you have your own account on MAIA, enter VISITOR when prompted "Please enter Observer's identification".
  • Type STARTUP at the $ prompt and wait until the TEL$ prompt appears.
  • The current setup can be shown by entering
    TEL$ DISPLAY CONFIGURATION
    To return to the observer's display, use the command
    TEL$ DISPLAY
  • If you have your own account on MAIA, load your telescope control file using the command TEL$ CFILE your-filename
    Otherwise, the setup may be changed by entering individual configuration commands, e.g.,
    TEL$ CONFIGURE FOCAL_STATION NASMYTH_A
    TEL$ CONFIGURE FOCUS_CONTROL COMPENSATED
    TEL$ CONFIGURE ROTATOR_REFERENCE POSITION_ANGLE
    TEL$ CONFIGURE ROTATOR_ORIENTATION SLIT
    See MSSSO Telescopes Command Reference Manual, a hardcopy of which is stored in the console room.
  • Open communications with DBS autoguider hardware by typing
    TEL$ ENLIST TXA6
  • Lights within the building are controlled by two lighting switches at the top centre of the console. Set to FLUOROS OFF and INCAND OFF (or INCAND PRESET).

  • If it is safe to do so, open the building shutter. Press BUILDING SHUTTER OPEN on the console. Always ensure that the mirror cover is fully closed before opening or closing the building shutter, to avoid debris to fall on the mirror.
  • To start the building ventilation fans, press VENTILATION FANS ON on the console.
  • Open the mirror cover. MIRROR COVER OPEN on the console.
  • Calibrate telescope pointing. To set the default DBS aperture, send the telescope to a known star's position (mag 4 - 8) and type
    TEL$ APERTURE 1
    Looking on the autoguider display, move the telescope to place the star at the slit centre (in line with the decker) type
    TEL$ CALIBRATE APERTURE
    More sophisticated calibration options with custom apertures can be performed.
  • Focus the telescope by using the autoguider camera as a TV display while driving the focus controls manually. See the autoguider manual sections 5 & 6.

    Taking Exposures

    DBS control PC
  • Computer control of DBS hardware such as slit width, decker and arc lamps is from the PC labelled "Imager-DBS" at the left hand end of the main console. If the DOS prompt is showing, run dbs from the \dbs directory. Then select "control/status" from pull-down menus.
  • Arc lamps are automatically switched on when the arc mirror is set to "IN" and switched off when the mirror returned to "OUT".
  • Check the TV slide is centred; value around 0.

    Setting up the CCDs

  • The CCDs are run by Astromed controllers on a pair of workstations to the left of the telescope console. All interaction with the CCDs is now performed via the CICADA GUI. See Taking Exposures for details of their operation.
  • When not in use, the CCDs should be left on "CCD temp + flush".
  • To set the CCD read-out window, use the CICADA pull-down menus.
    To check the read-out window is correctly centred, drive the decker in until it occults part of the slit (see The Decker). Use the autoguider to watch as you drive the decker in. Take an exposure with any lamp and the dark band where the decker obscures the slit should lie at the middle of the defined window. The pixel scale is 0·91 arcsec/mm.
  • Make sure the window has an overscan region at right side of image, since any bias structure normally takes the form of horizontal bands. Remember the monitor does not display the full 1850 pixel width of the image. (See Taking Exposures.)

    End Of The Night

  • At the telescope control terminal, enter
    TEL$ PARK
  • When the telescope stops moving, enter
    TEL$ SHUTDOWN
    and wait until the system advises that it is safe to leave. The mirror cover and building shutter will be closed automatically, but should be checked by the observer.
  • Finally you may optionally enter
    TEL$ CONSOLE OFF
  • Restore building lights to normal.
  • Fill dewars.
  • At the end of your run, fill in the online Observer's Report form.

    The Autoguider / Acquisition CCD Camera

    See also the 2·3m autoguider manual.

    The slit is visible in autoguider camera. The orientation is reversed by default - e.g., N up, E to right. When slit is in position angle 90, the left end of the slit points E. Note however that the autoguider display has options to flip and rotate the image to any orientation.

    Calibrations

    (For telescope pointing calibration, see `Start of the night' above)

    Flats
    Some observers have reported dome flats are better than the internal Quartz lamp, except in the UV. Twilights flats are generally required for correcting the slit illumination in the flats.

    Dark Frames
    Dark current is small, about 0·5 electrons/pixel/hour, so dark frames have not generally been necessary.

    Bias
    The repeatable bias structure is small; typically ±1 in B and ±3 in R. In my experience you want >>10 bias frames to really measure it properly. Do not mistake random noise which often appears for genuine bias structure. Using too few biases which include random rubbish will make you data worse, not better. The CCD controller sometimes creates considerable noise in the form of coarse horizontal striping, which cannot be corrected by bias frames. (It looks a little like a badly tuned TV signal.) This must be cleared by reinitialising the CCD hardware (from the CICADA pulldown menu), but this also resets the bias levels rendering the old bias frames unreliable.

    Where To Find Your Data

     Your data will be in the subdirectory created for you when you ran "teldisk" and visible through the CICADA "Preferences" pulldown menu. You need to back up your data BEFORE you leave the telescope, because your data will be automatically deleted when the next user runs "teldisk".

    You can write your data to tape using tar or your favourite data writing command on the tape drive located on "mudslide" in the Console room. However, various observers have had problems in reading their tapes written on this drive when they got home. Many observers nowadays prefer to back up their data on their personal laptops at the end of their run. RSAA does not have an archive of data taken at the 2.3m at this stage, therefore all data that has not been properly backed up is lost.

    This page is http://www.mso.anu.edu.au/observing/2.3m/DBS/dbs_getgoing.html


    Last modified: Wed Aug 10, 2005 by Marilena Salvo (salvo@mso...)