Appendix 7 - Sample Flat Fields

This appendix contains pointers to a number of sample flat fields. These are provided so you can quickly check that the flat fields you get look roughly right. Small changes (eg appearance and/or disappearance of dust doughnuts) can be expected from run to run.

Two files are available for each image. One is a GIF image showing the flat-field in gray scale (about 0.4Mb). The other is a compressed, FITS file (~1.7Mb for a 1024x1024 image) which you can retrieve and display yourself.

The appearance of the flat fields does not depend on the speed at which they are taken, though the number of electrons collected for a given light level does.

Note : that the GIF and FITS images will appear `upside-down' (ie flipped vertically) relative to the display you will see on the XMEM as data is taken.

Hyperlinks to Sample Images
Camera/Chip/Speed Filter GIF
FITS Comments
f/3.3 + TEK U (CuSO4) f33_tek_cus04skyflat.fits.gz The dark region in the lower left corner of this flat is thought to be caused by the bubble which is present in the liquid CuSO4 filter. This bubble moves around the filter as the telescope's position changes.
KPNO B f33_tek_bdomeflat.fits.gz
KPNO V f33_tek_vdomeflat.fits.gz
KPNO R f33_tek_rdomeflat.fits.gz
KPNO I f33_tek_idomeflat.fits.gz
Bias f33_tek_bias.fits.gz
f/1 + Thomson/Nonastro V f1_th_vskyflat.fits.gz
R f1_th_rskyflat.fits.gz
I f1_th_iskyflat.fits.gz

Introduction The Telescope & Optics The Detectors
The Imaging Cameras An Imaging Cookbook The Data you Take Away
Exposure times OFFSET_RUN files CCD Windows Data Catalogs
On-line Reduction Filters Flat-fields Blank Fields Orientation Shutters

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This Page last updated:  7 Sep 1997, by Chris Tinney