This file describes the data model for the Arc image.
It is generally a simple combination of all input arc frames.
The image is written to disk as a multi-extension FITS file
prefixed by Arc in the Calibrations/ folder.
See :ref:`calib-naming` for the naming convention.
The first extension is the combined image. You can view it with any standard image viewer, e.g.:
ginga Calibrations/Arc_A_1_01.fitsMost often you use only one arc frame and this appears very similar to the raw image. If you do stack several, the output could be quite different.
The image will also be a trimmed portion of the raw image and also re-oriented so that vertical is the spectral dimension with blue at the bottom, following the PypeIt :ref:`pypeit-orientation`.
Here is an screen shot of a ginga view
for an example from the shane_kast_red spectrograph.
Yup, an arc.
If your image appears to be in err, here are the things to consider:
- Is one or more of your input arc frames junk?
- Is one or more of your input arc frames mis-labeled?
Internally, the image is held in :class:`~pypeit.images.buildimage.ArcImage`, which subclasses from :class:`~pypeit.images.pypeitimage.PypeItImage` and :class:`~pypeit.datamodel.DataContainer`.
The datamodel written to disk is: