cone_search

Catalog.cone_search(ra: float, dec: float, radius_arcsec: float, fine: bool = True) → Self

Perform a cone search to filter the catalog.

Filters to points within radius great circle distance to the point specified by ra and dec in degrees. Filters partitions in the catalog to those that have some overlap with the cone.

Parameters:

rafloat

Right Ascension of the center of the cone in degrees

decfloat

Declination of the center of the cone in degrees

radius_arcsecfloat

Radius of the cone in arcseconds

finebool, default True

True if points are to be filtered, False if not. Defaults to True.

Returns:

Self

A new Catalog containing the points filtered to those within the cone, and the partitions that overlap the cone.

Examples

Filter a small synthetic catalog to a cone on the sky:

>>> import lsdb
>>> from lsdb.nested.datasets import generate_data
>>> nf = generate_data(1000, 5, seed=42, ra_range=(0.0, 300.0), dec_range=(-50.0, 50.0))
>>> catalog = lsdb.from_dataframe(nf.compute()[["ra", "dec", "id"]])
>>> cone = catalog.cone_search(ra=150.0, dec=0.0, radius_arcsec=7200)
>>> cone.head()
                            ra       dec    id
_healpix_29
1917605570237722650  151.359297  1.383203  4296