lickbase input output
For each input image in the input image list the last column is assumed to be a baseline column as would be produced by the Lick Data Acquisition Systems on Mt. Hamilton. The appropriate manipulations of the image are made, and then the colbias task is called to perform the bias fitting.
It is required that the IRAF parameters for the colbias task have already been set before running lickbase. Specifically, the user will wish to ensure that the "function", "order", "*_reject", and especially the "interactive" parameters are correctly set.
As the image is output, the OVERSCAN card and several other cards which are useful for the ccdproc task are inserted with suitable values. Images which already contain an OVERSCAN card will be flagged and not modified by this task. Thus, it should be safe to run this task twice over the same images without causing any harm. The image is not trimmed, but the TRIMSEC card is inserted so that ccdproc will be instructed to trim off the last column.
The parameters rdnoise, gain, dispaxis, and observat are for convenience. The Lick data-taking system does not insert these cards, but several IRAF tasks make use of them.
Note carefully that, as far as ccdproc is concerned, a binned detector is a different detector than the same detector with unit binning. The value of the RDNOISE card should be different for a binned detector. The value of GAIN can also vary depending on fast/slow readout modes and over time. Furthermore, when any kind of binning is requested on a Lick CCD, the gain of the amplifier is automatically reduced by a factor of 4.
If rdnoise is specified, it should be given in electrons (i.e., photons), NOT in DN. If gain is specified, it should be given as the number of electrons (photons) per DN. See, e.g., combine, imcombine, apphot.datapars, and apall for discussion of the use of RDNOISE and GAIN.
DISPAXIS is used by many of the spectral extraction tasks. OBSERVAT is used to set the position of your telescope for airmass, position angle, and other such calculations (see observatory).
N.B.: lickbase places temporary files in the directory specified by the IRAF cl variable "tmp". It is advised that you "reset tmp = /a/big/local/disk" in your loginuser.cl file.