C40/CCD Observing Procedures


Last modified on May 26, 2012 (Nidia)

IMPORTANT: START BY CHECKING THAT WE HAVE THE RIGHT FILTERS IN THE CAMERA:
LC-3013 (B), LC-9844 (V), u', g', r', i'


  • Initializing systems
  • Calibrations
  • Opening dome, and Preparing Telescope Control System (TCS)
  • Skyflats
  • Telescope Zero-Point
  • Focusing the Telescope
  • Using the guider
  • Observing
    WARNING: Sometimes it may happen that a slew gets aborted, with a "Slew correction too large! Slew aborted!" message issued to the 'System Messages' window in the TCS screen. A new SLEW will send the telescope to the desired position, but you must type also DOME AUTO in order to reset the dome motion, otherwise it will get stucked at MAN status.

  • Transferring data at end of night
  • Closing the Telescope
    • Turn OFF power of guiding camera in lightblue rack
    • Push OBTURADOR on console to close shutter
    • Push ASENCION RECTA on console to turn OFF tracking
    • In TCC-Guider PC, type 'DOME IDLE' to de-activate dome rotation
    • In TCC-Guider PC, type 'DOME PARK' to park dome to the south
    • In TCC-Guider PC, type 'COVER' (telescope will slew south)
    • Go to the platform, raise platform, and put on the telescope cover
    • Lower platform
    • Rise windscreen
    • Turn OFF fans in adjacent room (turn OFF switch and set reostat to zero)
    • In TCC-Guider PC, type 'ZENITH' (telescope will slew to the zenith)
    • Turn Power OFF on console
    • Turn console OFF (rotate key)
    • Turn OFF monitors in control room
    • In 'gdr' window click CENTERFIELD
    • Fill out Night Report here
    • You can go party now
  • Shutter timing and linearity tests (alternative program for cloudy nights)
      If you cannot open the dome because it is overcast, it would useful if you could carry out
      shutter timing and linearity tests following the following instructions:

    • Shutter test
      • Wait until the sky is dark and close the dome.
      • Turn off the incandescent lights from the console.
      • Point the telescope to the zenith.
      • Set the subraster to [1310:1510,501:701]
      • Turn on the quartz lamp and adjust the intensity until you get about 10 kcounts/pix in 30 sec. Then use the MULTIPLE option to get a 10x3sec exposures, followed by a single 30sec expsoure. Repeat this procedure until
        you have about 10 pairs of long-short images.
    • Linearity test
      • (Mario Exposure Times)
      • Wait until the sky is dark and close the dome.
      • Turn off the incandescent lights from the console.
      • Point the telescope to the zenith
      • Set the subraster to [1310:1510,501:701]
      • Turn on the quartz lamp and adjust the intensity until you get 100 counts/pixel (above the bias which is ~600 counts/pix) in 8 seconds.
        Then take exposures of 4, 8, 16, 8, 24, 8, 32, 8, 48, 8, 64, 8, 80, 8, 96, 8, 120, 8, 144, 8, 180, 8, 240, 8, 320, 8, 400, 8, 500, 8, 600,
        8, 700, 8, 800, 8, 1000, 8, 1200, 8, 1300, 8, 1400, 8, 1500, 8, 1600, 8, 1700, 8, 1800, 8. Feel free to stop this sequence when
        you reach 24 kcounts/pix. The 8 sec exposures are used to control the illumination variations. With the task imstat you can
        check the illumination level in the 8-sec exposures. If you notice large (> 3%) variations please get another sequence.
      • (Carlos Exposure Times - Optional)
      • Turn on the quartz lamp and adjust the intensity until you get 200 counts/pixel above the bias (which is ~700 counts/pix) in 8 seconds.
        Then take exposures of 8, 8, 8, 12, 8, 16, 8, 20, 8, 28, 8, 24, 8, 28, 8,
        32, 8, 36, 8, 40, 8, 80, 8, 120, 8, 160, 8, 200, 8, 240, 8, 280, 8, 320, 8,
        360, 8, 400, 8, 440, 8, 480, 8, 520, 8, 560, 8, 600, 8, 640, 8, 680,
        8, 720, 8, 760, 8, 800, 8.
        If possible, take another sequence.