Forwardport PR 261 to main (ALOHA 2024: Clean up photometry contents)

[pllim]

Forwardport #261

Fix #263

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[mwcraig]

This looks good to me. I did not check all of the new links but did spot check a couple, which worked.

[pllim]

Is there a way to run link check on all the workshop notebooks going forward? 🤔

[larrybradley]

I see that 25.9463 is the 2012 zeropoint, but the change here to 25.936 doesn't agree with the current zeropoint calculated in stsynphot.

I get 25.94471861842982. (25.944).

The other changes are all fine.

[pllim]

25.936 doesn't agree with the current zeropoint calculated in stsynphot

The WFC3 site mentioned in notebook (https://www.stsci.edu/hst/instrumentation/wfc3/data-analysis/photometric-calibration/ir-photometric-calibration) said values are from 2020 "for an infinite aperture of radius 6 arcsec". stsynphot follows whatever lookup tables are available at the time (which is probably newer than 2020) and also depends on exact obsmode (see https://stsynphot.readthedocs.io/en/stable/stsynphot/appendixb_inflight.html#wfc3).

[pllim]

So if you want the canonical source to be stsynphot , description also needs to be updated and you might have to add stsynphot calls to the notebook, which is probably overkill.

[pllim]

If you want the values to be from 2012, then might have to update the URL because I cannot easily find 25.9463 on that page for that filter.

[larrybradley]

Here are the 2012 values:
https://www.stsci.edu/hst/instrumentation/wfc3/data-analysis/photometric-calibration/ir-photometric-calibration/previous-ir-photometric-calibration

I think it's fine to update, but we should probably use the best current value. I used an obsmode of 'wfc3,ir,f160w' which is also for an "infinite" aperture. See https://spacetelescope.github.io/hst_notebooks/notebooks/WFC3/zeropoints/zeropoints.html. It's interesting the that current calibration value is very close to the 2012 value, but the 2020 value has a larger difference.

[larrybradley]

I also tried changing the MJD to the range spanned by the observations, but the zeropoint differences are ~1e-8.

[pllim]

Weird... should we send in help call to WFC3 Team?

As for the notebook, I am not sure how to modify the text to say value is from stsynphot without overcomplicating things (the PYSYN_CDBS stuff is a pain to set up if users want to reproduce it). Should I just revert the zeropoint stuff from this PR?

[larrybradley]

Can you simply say it's the latest zeropoint from stsynphot and use the HST notebook URL as a reference?

[pllim]

Sure, I can. Meanwhile, I submitted INC0206518 to HST Help Desk.

[pllim]

@larrybradley , I added a commit to address your zeropoint concerns. FYI.