The script mdotwilight.script (dotwilight.script) allows one to create sky flats automatically with Minicam (4shooter). The script determines the date of observation and calculates the appropriate exposure times, given the readout time of Minicam (4shooter). It also determines which filter is in place, and uses it to expose. Its output file names are "X.FLATSkyY.fits," where X is the CCD sequence number and Y the first character in the name of your filter. The calculation is based on the algorithm of Tyson and Gal (1993 AJ, 105:1206). The script also takes the exposures for you, starting where the telescope was pointed initially (preferably near zenith). NOTE: the script works at both dusk and dawn.
Before running the script, you need to determine an exposure time T that yields 10-12K counts on average. You might do this by trial and error at the beginning or end of your first night. Once you have determined T, in the rtshell, type "mskyflat" ("skyflat"), an alias to "source /home/4obs/scripts/mdotwilight.script" ("dotwilight.script"). The script will prompt you for the number of exposures you desire, the initial exposure T and the binning you are using. It will then start a sequence of exposures and offset the pointing 50 arcsec W between each exposure. It should maintain an average of 10-12K counts in each exposure.
If you have any comments, please send email to E. Falco and be as specific as possible.