search_around_sky#
- astropy.coordinates.search_around_sky(coords1, coords2, seplimit, storekdtree='kdtree_sky')[source]#
Searches for pairs of points that have an angular separation at least as close as a specified angle.
This is intended for use on coordinate objects with arrays of coordinates, not scalars. For scalar coordinates, it is better to use the
separation
methods.- Parameters:
- coords1astropy:coordinate-like
The first set of coordinates, which will be searched for matches from
coords2
withinseplimit
. Cannot be a scalar coordinate.- coords2astropy:coordinate-like
The second set of coordinates, which will be searched for matches from
coords1
withinseplimit
. Cannot be a scalar coordinate.- seplimit
Quantity
[:ref: ‘angle’] The on-sky separation to search within.
- storekdtreebool or
str
, optional If a string, will store the KD-Tree used in the search with the name
storekdtree
incoords2.cache
. This speeds up subsequent calls to this function. If False, the KD-Trees are not saved.
- Returns:
- idx1
int
array
Indices into
coords1
that matches to the corresponding element ofidx2
. Shape matchesidx2
.- idx2
int
array
Indices into
coords2
that matches to the corresponding element ofidx1
. Shape matchesidx1
.- sep2d
Angle
The on-sky separation between the coordinates. Shape matches
idx1
andidx2
.- dist3d
Quantity
[:ref: ‘length’] The 3D distance between the coordinates. Shape matches
idx1
andidx2
; the unit is that ofcoords1
. If eithercoords1
orcoords2
don’t have a distance, this is the 3D distance on the unit sphere, rather than a physical distance.
- idx1
Notes
This function requires SciPy to be installed or it will fail.
In the current implementation, the return values are always sorted in the same order as the
coords1
(soidx1
is in ascending order). This is considered an implementation detail, though, so it could change in a future release.