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Flat-field and Arc Lamps

The lamps are turned on or off using the VAX terminal. All lamps are turned off using the command LAMPSOFF.

All of the lamps are mounted above the prime focus cage, pointing up. All flat-fields and arc lamps require the telescope to be pointing at the dome; imaging dome flats should be taken with the telescope vertical and the shutters closed (to point at the white painted portion of the dome). The primary mirror cover must also be in the open position (see someone on the day crew to show you how to do this).

The appropriate lamp for direct imaging flat-fields is turned on with the command LOWLAMP.

The appropriate lamp for spectroscopic flats is turned on with the command HIGHLAMP.

The arc lamp (Hg and Ar together) is turned on with the command ARCLAMP.

The typical exposure times for some of the flats and arc are given in Table 7.


Table 7
Typical Exposure Times for Flats and Arcs
Setup Lamp Type Exposure Time (seconds)
Imaging, g filter LOWLAMP 30
Imaging, r filter LOWLAMP 8
Imaging, i filter LOWLAMP 3
Spectroscopic flat, 1.5'' slit HIGHLAMP 4
Arc (Hg+Ar), 1.5'' slit ARCLAMP 180



next up previous
Next: Orientation of COSMIC Up: User Manual for COSMIC Previous: The Grism Wheel
Roy Gal
4/25/1998