bias: make a bias observation and archive the data

Function:

bias clears the CCD mosaic, and immediately reads out the CCDs, saving the images as four runs in FITS files. The files are passed to the archiving and logging facilities.

The command handles the necessary interactions with the shutter and autoguider. The shutter is closed before the CCDs are cleared. At the end of the readout, the shutter opens again to let the autoguider see the sky. If the system is autoguiding at the start of the run, it will autoguide again after the run finishes.

A title may be given for the observation: the title appears as the datum of the OBJECT keyword in the FITS headers and as the target name in the observing log. If no title is given, the runs are titled "Bias frame".

Usage:

   bias ["title"]
The title-string must be enclosed in double quotes.

Notes and caveats:

Each run generates four FITS files, each with a different run-number. For a particular file, the name of the CCD that produced it may be recovered from the FITS keyword CHIPNAME and the CCD number (1..4) from DASCHAN.


This page is wfcbias.html v1.2 by Guy Rixon, last revised on 97/05/29.