Let’s say you have an object you are interested most, a star, a galaxy or a cluster. And you would like to know what objects appear around that. This is why you would want a cone search. A cone search is defined by coordinates right ascension and declination on the sky and a search radius.
On Gaia@AIP, there are two ways to perform cone searches: through the query interface or using the cone search API.
The Cone search from Gaia@AIP is available through the Query interface. You’ll have to select the Cone search form under New query job on the left side of the page.
Through the form, you can enter the right ascension and the declination in degrees and the search radius in arcsecs, defining a cone on the sky. Your input is then, translated into a ADQL query with the same parameters and the results are served as a result table and stored in you Private database. The PostgresQL query is of the form:
SELECT ra, dec, DISTANCE( POINT('ICRS', ra, dec), POINT('ICRS', INPUT_RA, INPUT_DEC) ) AS dist FROM gdr2.gaia_source WHERE 1 = CONTAINS( POINT('ICRS', ra, dec), CIRCLE('ICRS', INPUT_RA, INPUT_DEC, INPUT_RADIUS) )
Cone search API
The Cone Search API is one of the first and most successful protocols recommended by IVOA. The API for the
gdr2.gaia_source table is located at https://gaia.aip.de/conesearch/api/gaia_source/ and expects the parameters: RA (in degree), DEC (in degree), SR (in degree). An optional verbosity parameter VERB set to 1,2, or 3, can be provided, with VERB=1 selecting only
source_id for every object, VERB=2 selecting the most important columns, and VERB=3 selecting all columns.
You will retrieve a VOTABLE document by visiting an URL like https://gaia.aip.de/conesearch/api/gaia_source/?RA=245.89675&DEC=-26.52575&SR=0.01. (E.g. for a radius of one degree around M4).
You can use the cone search api for scripted access using your favorite HTTP command line client, e.g.:
wget 'https://gaia.aip.de/conesearch/api/gaia_source/?RA=245.89675&DEC=-26.52575&SR=0.01&VERB=2' curl 'https://gaia.aip.de/conesearch/api/gaia_source/?RA=245.89675&DEC=-26.52575&SR=0.01&VERB=2' http 'https://gaia.aip.de/conesearch/api/gaia_source/?RA=245.89675&DEC=-26.52575&SR=0.01&VERB=2'
Topcat is a Tool for Operations on Catalogues And Tables. The cone search interface in topcat can be accessed from the VO menu. In the Cone search interface enter our API endpoint
https://gaia.aip.de/conesearch/api/gaia_source/ under Cone URL. (We will add our service to the VO registry to be selected through the search window soon.). You can than choose RA, DEC and SR and retrieve the results of your request directly in topcat.