Catalog Cone Search
Simple cone search service on the NOMAD, USNO-B1 and USNO-A2 catalogs. This service is a Virtual Observatory compliant cone search. A cone search extracts all the objects within a user specified radius around a single point in the sky.
Welcome to the USNO
Integrated Image and Catalog Archive Service
VO Compliant Catalog Cone Search Page
To extract a region from one of the catalogs listed below, you will need to enter the RA and Dec of the center of the region (both in DEGREES), and the radius in degrees of the search area. Verb(osity) controls the number of possible table columns returned: 1 is the least, 3 is everything in the table. Then click on the "Submit" button on the appropriate catalog line. Data are returned in VOTable format (an XML based format agreed upon by the Virtual Observatory groups around the world).
Service Note (20 Nov 2006 2:35pm MST): We are expecting to upgrade some of our network hardware over the course of this week (and maybe into next week). There will likely be some interruptions of this service as a result. We will try to keep the interference to a minimum.
Each of these catalog cone-search services can be accessed directly using a GET style command. The format is
http://www.nofs.navy.mil/cgi-bin/vo_cone.cgi?CAT=USNO-B1&RA=1.0&DEC=-10.0&SR=0.1&VERB=1 CAT is the catalog ID, and can be NOMAD, USNO-B1, USNO-A2, or ACT. RA is the RA in decimal degrees. DEC is the DEC in decimal degrees. SR is the Radius of the conesearch region in degrees. VERB regulates the number of fields returned for each matching entry. 1 is the least, 3 is the most.
There are several optional parameters that are supported that are not specified by the VO standard. They are made available in the hope that they will provide useful additional functionality. The parameters are:
clr = the primary selection color bri = Bright Magnitude limit for culling the returned catalog fai = Faint Magnitude limit for culling the returned catalog cftype = file type for returned data (XML/VOTable style, or ASCII) slf = RA/Dec formatting style skey = file sort key
The Faint Magnitude limit is used in determining the maximum region size that is permitted. The default maximum region A is a cone with a radius of 1.0 degrees. If the Faint Magnitude limit is SMALLER than 25.0, then the allowed region area increases in size as A*2.5^[(25-Fmag)/4]. So, if you are only interested in objects down to 12 magnitude, the allowed region area increases in size by a factor of slightly over 19, or the maximum radius increases by a bit over 4. The hard upper limit in radius is 12 degrees.
Last updated: 2008Dec16 by sel