Basic catalogs

[stscijgbot-rstdms]

Issue RCAL-719 was created on JIRA by Nadia Dencheva:

Write code to generate a basic catalog which includes

(a) The position of each source in ICRF coordinates (b) The estimated flux of each source (c) Whether the source is a point source or extended object.

In the jwst pipeline this is the step

[source_catalog

 

[stscijgbot-rstdms]

Comment by Brett Morris on JIRA:

Nadia Dencheva – photutils uses DAOStarFinder to detect sources, which also measures "sharpness" and "roundness" for each source (see docs for definitions). Would these suffice to address (c) ("Whether the source is a point source or extended object")?

[stscijgbot-rstdms]

Comment by Eddie Schlafly on JIRA:

It's not entirely clear; we'll have to ask Tyler et al. at an upcoming meeting.  But we haven't been given any other algorithms and full morphological fits aren't required for a while, so it's only reasonable to use a heuristic of this form.  It may be a good idea for us to choose some particular roundness / sharpness thresholds to provide a boolean.  The other algorithm I've used is "spread model" from sextractor, which would probably be worth implementing if it's not already in photutils++.

[stscijgbot-rstdms]

Comment by Nadia Dencheva on JIRA:

The JWST code is here

https://github.com/spacetelescope/jwst/tree/master/jwst/source_catalog

I think we're OK if we have something similar as a baseline. The code was developed by Larry so he can answer questions on it. Note that this is where the photometry keywords are applied in jwst. I'm not sure what the plan for Roman is.

 

 

[stscijgbot-rstdms]

Comment by Brett Morris on JIRA:

In this draft PR, I create a basic source catalog during source detection step. This can be moved to its own step, as in jwst, if we want: #1029

[stscijgbot-rstdms]

Comment by Nadia Dencheva on JIRA:

Coding is done in #⁠1029. Regression tests will follow up.