Dear all, There is a problem I have been running into with the background estimation for co-added images. It is quite simple to find out the subtracted background for calexp images, but I am not able to do the same for the co-added ones. If anyone has any pointers on how to do it I’ll be really gr…

Hi Nandini, thanks for posting this question. Could you share an example of the code you tried and the error message that was returned when it failed?

Hello Melissa, thank you for your response. I am looking for some sort of documentation of the co-add images to retrieve the background estimation. So there is a tutorial for how to obtain the background for a calexp frame, as given in Notebook 5 on the RSP: bkgd = butler.get(‘calexpBackground’, *…

Try the deepCoadd_calexp_background dataset type.

Thanks @price . Since I didn’t know much about working with the subtracted backgrounds, I’ve drafted a notebook to explore them. It’s here in my branch of the delegate-contributions-dp01 repo: https://github.com/rubin-dp0/delegate-contributions-dp01/tree/u/melissagraham/backgrounds I have a couple…

Backgrounds are subtracted off the individual images before coaddition, so there isn’t much background to subtract from the coadd.

Thank you for your reply @price Are the values in the deepCoadd_calexp_background images weighted for the individual calexp images that have been stacked to create the Coadd frames? And is there a place where it is possible to read more about the background dataset for such kind of information in …

The coadd background is just measured from the coadd. There’s no direct weighting; maybe the variance plane is used, I don’t remember. I don’t think there’s much LSST documentation on background estimation. I know there are Community posts about sky frames. There should be some information in the H…

Thanks @price and @nandinihazra . To the intro-to-backgrounds draft notebook I added links to Bosch et al. (2019) and to the Data Management Science Pipelines Design document which I think are currently the best two places to read more about background subtraction. @nandinihazra I think you might fi…

Thanks again @nandinihazra for bringing this up, and for reviewing the notebook for me. Any readers who are looking for this notebook, see: [image] New contributed notebook on subtracted backgrounds Data Preview 0 In the shared delegate-contributions-dp01 rep…

Background subtracted from co-adds

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MelissaGraham (Melissa Graham) February 24, 2022, 6:32pm 10

Thanks again @nandinihazra for bringing this up, and for reviewing the notebook for me.

Any readers who are looking for this notebook, see:

Topic		Replies	Views
New contributed notebook on subtracted backgrounds Support dp0	6	2024	March 10, 2022
Questions about background subtraction and reference catalog Data Management	6	1331	April 19, 2019
Difference between deep_coadd and a custom coadd Support imagedifference , deep-coadd-image , custom-coadd	4	149	September 30, 2026
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Background subtracted from co-adds

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