write selected LSST Stack package versions and tags to FITS primary header

[jchiang87]

No description provided.

[coveralls]

Coverage increased (+0.2%) to 72.951% when pulling 31d7c2f on issue_231/write_stack_versions_and_tags into d1eac95 on master.

[jchiang87]

@cwwalter This is ready to go.

[cwwalter]

OK this looks good to me. Two things I noticed you could consider:

• This was actually already true before this change for the imSim version number, but we are only going to see these keywords on the electronics readout versions. Would it be good to (eventually?) do it in the e-image and then would they automatically be copied over to the version during readout? I think as it is, e-image files will have no provenance. If we only view them as debugging items maybe that is OK, but if we ever stored them as a base we might miss it.

• The test doesn't check the tag vs version capability you build into the code and are using.

[jchiang87]

Unfortunately, getting this info into the eimage is difficult since the FITS file writing is done by the galsim Image.write function and there's no direct interface to manipulating the header keywords before writing. If we really want this, we'd need to update the file after it is first written.

[cwwalter]

Unfortunately, getting this info into the eimage is difficult since the FITS file writing is done by the galsim Image.write function and there's no direct interface to manipulating the header keywords before writing. If we really want this, we'd need to update the file after it is first written.

Ah, OK; too bad. Actually I think you already told me this in the past.

[rmjarvis]

Actually, anything you put into image.header should show up in the written FITS header.

[rmjarvis]

I don't think there's particularly good documentation for this feature, but this unit test should show you the syntax if you want to try it.

https://github.com/GalSim-developers/GalSim/blob/releases/2.2/tests/test_image.py#L2412

[jchiang87]

Thanks, Mike. I've updated the code to add the version keywords to the eimage files following the galsim example, and I refactored the version keyword handling so that we can test some of that functionality directly.

Unless I hear otherwise, I will merge this into master at 5pm PT today, and will tag the imSim release for Run2.2i.