Use Alignment moc in crossmatch/join operations

[smcguire-cmu]

Uses the PixelAlignment object's moc as the moc in the output catalogs of join and crossmatch operations.

Fixes #428

[camposandro]

I noticed that the filtered structures on search operations are also not carrying the mocs:

lsdb/src/lsdb/catalog/catalog.py

Line 326 in c478401

filtered_hc_structure = search.filter_hc_catalog(self.hc_structure)

Do you want to address it in this PR or should I open a new issue?

[smcguire-cmu]

I'm pretty sure the searches do carry the mocs. The filter_hc_catalog method calls the filter_by_moc or filter_by_healpix_pixels methods in hipscat that include the filtered moc.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.87%. Comparing base (ab3f57a) to head (c7dd949).

Additional details and impacted files

@@             Coverage Diff              @@
##           development     #438   +/-   ##
============================================
  Coverage        97.87%   97.87%           
============================================
  Files               44       44           
  Lines             1601     1601           
============================================
  Hits              1567     1567           
  Misses              34       34           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[camposandro]

Sorry, you're right, search operations carry the MOC over if the catalog already has one! If not, we could still generate a MOC from the catalog's pixel tree. I opened issue astronomy-commons/hats#378.

Can you please point the docs hipscat to its development branch?