JKT dome flats
There has been a large interest in dome flats recently. So on a weathered out night a small study was conducted to find out UBVRI exposure times and light levels in the dome. This will reduce the need for "guestimates" in the future.

Positions:

  • telescope: from Zenith park, increase DEC until AM=1.7.
  • dome: 235 degrees

    Each exposure was aimed to reach a mean pixel value of 20000ADU, consistent with 1/3 of the saturation level of the SITe2 chip. The readout speed was set to QUICK.

    Band: U (RGO 203)
    lamps: Main dome lights on
    dial: -
    exposure time: 125s
    mean: 19109
    stddev: 8689
    midpix: 23046

    Band: B (Harris 28)
    lamps: 1,2,3 & 4
    dial: 10
    exposure time: 5s
    mean: 18672
    stddev: 8474
    midpix: 23410

    Band: V (Harris 31)
    lamps: 2 & 3
    dial: 5
    exposure time: 11s
    mean: 21729
    stddev: 10063
    midpix: 27046

    Band: R (Harris 39)
    lamps: 2 & 3
    dial: 2
    exposure time: 5s
    mean: 17914
    stddev: 7941
    midpix: 22045

    Band: I (Harris 44)
    lamps: 2 & 3
    dial: 1
    exposure time: 2s
    mean: 18241
    stddev: 8001
    midpix: 22375

    Terms:

  • lamps: There are four domelamp lights situated on the top ring of the telescope. Their controls are below the emergency stop button (labelled 1,2,3 & 4). The far right button must be depressed in order for the lights to come on.
  • dial: To the left of the dome light controls are three dials. The one labelled "DESK" controls the intensity of the dome light, and ranges from 1 to 10.
  • mean: Mean pixel value as decribed by iraf.imexam
  • stddev: standard deviation of pixel values as decribed by iraf.imexam
  • midpix: Median pixel value as decribed by iraf.imexam

    Exact filter characteristics can be found at: http://www.ing.iac.es/~quality/filter/filt.html .

    Dan Batcheldor
    ING Support Astronomer
    UH Placement Student