How can I most easily extract and use the PSF models from a DP0.2 calexp outside of the Science Pipelines environment? I’m looking for a low-dependency way to get the PSF for use in other astronomical code, without needing the Science Pipelines. My understanding is that these are PSFEx models. I…

First, a high-level comment: At the moment, while the image data products are all required to be FITS-4.00 conformant, and the image, variance, and flags/mask extensions should be straightforward to use in community software, we have not (yet) focused on making the substantial additional content in…

Within the RSP, we will provide services to provide some limited access to this information in non-stack mechanisms. For instance, we will have an API Aspect service that returns the PSF (as an image) for any point on any released image. This will be callable remotely and will also enable the Port…

Yes. I think that’s a reasonable goal.

But even simpler Python-only stuff would be useful. E.g., here’s a simple way to read and put together the PSF (at the reference X, Y position, no spatial variation in this treatment): import matplotlib.pyplot as plt import numpy as np from astropy.io import fits file = "image_calexp-r-896748-R1…

I’d be extremely reluctant to publish documentation committing to the HDU numbers to be used! That’s certainly not intended as a stable public interface of ours. I’ll research this offline and post something well-considered back.

[image] gpdf: HDU numbers to be used Yes, names should work just fine to access an HDU. Astropy can take names or numbers. Looking at a calexp file I have here the Psfex extensions are actually 10 and 11 (but maybe 12 is the one that matters?) The fundamental problem though is that they have…

Yes, that’s why I didn’t mention using the names. We really are going to have to discuss this offline for a bit.

How to extract PSFEx PSF from a PVI/calexp outside of Science Pipelines?

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gpdf (Gregory Dubois-Felsmann) November 10, 2023, 6:05pm 4

So, I think that what you trying to do is find a means to use the actual external psfex package to work with image files downloaded from the RSP environment, is that correct?

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How to extract PSFEx PSF from a PVI/calexp outside of Science Pipelines?

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