Crossmatch Access

The ALeRCE catsHTM API Wrapper gives an easy access to our crossmatch API that uses catsHTM.

Conesearch

To get all the objects inside a radius in a specified catalog, we use catshtm_conesearch(), where ra,`dec` is the center of the search and radius is the search radius in [arcsec].

from alerce.core import Alerce
#Import ALeRCE Client
client = Alerce()
ra = 10
dec = 20
radius = 1000
catalog_name = "GAIA/DR1"
cone_objects = client.catshtm_conesearch(ra,
                                dec,
                                radius,
                                catalog_name,
                                format="pandas")

Note

Without the catalog_name argument the function will return a dictionary with all available catalogs and the value is the conesearch in those catalogs.

Crossmatch

Similar to Conesearch, we look for the objects in a radius, but just get the closest object (catshtm_crossmatch()). This method is better used for a small radius.

ra = 10
dec = 20
radius = 20
catalog_name = "GAIA/DR1"
xmatch_objects = client.catshtm_crossmatch(ra,
                                dec,
                                radius,
                                catalog_name,
                                format="pandas")

Note

Without the catalog_name argument the function will return a dictionary with all available catalogs and the value is the crossmatch in those catalogs.

Redshift

Search if there is available redshift in a catsHTM catalog given position and a radius (catshtm_redshift()).

catalog_name = "GAIA/DR1"
redshift = client.catshtm_redshift(ra,
                                   dec,
                                   radius,
                                   catalog_name)