Taking Darks

This document covers taking darks with the SBIG ST-8E CCD camera using the Linux interface.

Generally, taking darks is identical to taking images, but the shutter does not open.

The command-line tool for taking images is dark_sbig.

It requires 2 mandatory command line arguments:

The exposure length
The name of the file to which to write the image

For example, to take a 10 s exposure, saving the image to Dark.fits, one would type:
dark_sbig 10 Dark.fits

Note that all images are stored in FITS format. You can view FITS files with:

xv
ds9

OPTIONS

There are options which can be appended to the command line which control aspects of the dark, and add information to the header of the FITS file.

Options which modify the image

-b n where n can be:
- 1 for no binning
- 2 for 2x2 binning
- 3 for 3x3 binning
The default is 1
-a c where c is the anti-blooming gate state:
- o for Off
- l for Low
- m for Medium
- h for High
The default is Off

Options which add information to the FIT header

-o "Observer Name"

For Example,
dark_sbig 200 Dark.fits -b 2 -o "Mr. Sulu"
would expose for 200 seconds, saving the dark in the file Dark.fits and recording the observer to be 'Mr. Sulu'. The OBJECT field of the FITS file is set automatically to DARK.