This file describes the data model for the Bias
image.
This is written to disk as a multi-extension FITS file prefixed by
Bias
in the Calibrations/
folder.
This is generally a simple combination of all input bias frames.
The first extension is the stacked image. You can view it with any standard image viewer, e.g.:
ginga Calibrations/Bias_A_1_01.fits
It should resemble any one of your input bias frames aside from:
- Having been overscan subtracted
- Being only a trimmed portion of the image
- Re-oriented so that vertical is the spectral dimension with blue at the bottom
Here is an example for the :ref:`keck-lris-red` spectrograph.
Pretty boring, as expected. Note that this is only 1 of the 2 detectors for this spectrograph.
If your image appears to be in err, here are the things to consider:
- Is one or more of your input bias frames junk?
- Is one or more of your input bias frames mis-labeled?
Internally, the image is held in :class:`~pypeit.images.buildimage.BiasImage`, which subclasses from :class:`~pypeit.images.pypeitimage.PypeItImage` and :class:`~pypeit.datamodel.DataContainer`. The datamodel written to disk is: