Dark
Overview
This file describes the data model for the Dark image.
This is written to disk as a multi-extension FITS file prefixed by
Dark in the Calibrations/ folder.
This is generally a simple combination of all input dark frames.
Inspecting
The first extension is the stacked image. You can view it with any standard image viewer, e.g.:
ginga Calibrations/Dark_A_1_01.fits
It should resemble any one of your input dark frames aside from:
Having been overscan subtracted (depending on the processing parameters)
Having been bias subtracted (depending on the processing parameters)
Being only a trimmed portion of the image
Re-oriented so that vertical is the spectral dimension with blue at the bottom
Trouble Shooting
If your image appears to be in error, here are the things to consider:
Is one or more of your input dark frames junk?
Is one or more of your input dark frames mis-labeled?
Current DarkImage Data Model
Internally, the image is held in
DarkImage,
which subclasses from PypeItImage and
DataContainer.
The datamodel written to disk is:
Version 1.3.0
HDU Name |
HDU Type |
Data Type |
Description |
|---|---|---|---|
|
… |
Empty data HDU. Contains basic header information. |
|
|
floating |
Primary image data |
|
|
floating |
Inverse variance image |
|
|
The detector (see |