reducing memory usage on OU TDE notebook

[jkrick]

This PR reduces memory usage in the TDE light curve notebook to address CI failures likely caused by memory constraints. It does not effect the science or goals of the notebook

Changes:

• Replace full-image background estimation (np.nanmedian/np.nanstd over 4088×4088 pixels) with a local annulus-based background using photutils SkyCircularAnnulus and ApertureStats
• Add del data in show_gallery() to free each full image array immediately after display
• Add del img in make_cutout() to free the full image array after the cutout is extracted
• Reduce default number of gallery images from 6 to 4
• Reduce default number of cutout images from 6 to 4

[jkrick]

maybe this closes #317 ?

[bsipocz]

maybe this closes #317 ?

yes, we should try it, I'm pushing directly to this branch

[bsipocz]

I suppose we should try the rendering, hopefully this will be enough

[bsipocz]

I suppose this should stay.

[bsipocz]

Trying to build on again, minor fix for the install cell

[bsipocz]

I started noticing new issues in CI, namely that we run out of disk space when we run all the notebooks. I don't think right now that you can or should do much about it in the individual notebook level.

xref #333

[bsipocz]

rebased to retrigger CI

[bsipocz]

The test failures are consistently present, but most likely are not related to the changes in this PR as I saw them in #335.

I'm not sure of the preference if we want to include that in this PR, too or want to fix them separately.