Pointings show circular artefact

[anawas]

Summary

Flux drop and circular artifacts in pointings, plus severe slowdown when loading sky model with source IDs.

Description

Two main issues have been observed in the Karabo project:

1. Pointing and Mosaic Artifacts

   • Individual pointings show a well-sampled spherical area, but flux drops sharply outside this region.
   • This effect persists even without the primary beam and creates visible circular borders in mosaicked images.
   • The issue becomes more pronounced when using smaller pointing radii.
   • Tested with OSKAR backend; problem still occurs.

2. Sky Model Loading and Performance

   • Using SkyModel.add_point_sources(sky_data) loads sources without a source_id (14D array instead of 15D).
   • Using SkyModel.get_sky_model_from_h5_to_xarray(path) adds source_id (all zero), but drastically slows down line_emission_pipeline() (~1 second per source).
   • Unclear why adding source_id impacts runtime so heavily.