Back to Quasars/Cosmology index

Search by position (open tool in new window)

1. One of the constraints you can use is to find quasars only in a specific part of the sky. Use the Position Constraints box to choose constraints. You can choose not to use any position constraints (None), or you can choose one of three types (Rectangle, Cone, and Proximity).

   1. None finds objects all over the sky.

   2. Rectangle finds objects within a rectangle between a minimum and maximum RA and Dec. Enter minimums and maximums for RA and Dec, either in decimal degrees or in HMS/DMS. HMS input can be formatted as either HH:MM:SS.ss or HH MM SS.ss.

   3. Cone finds objects within a radial patch of sky defined by a center RA and Dec and a radius. The maximum search radius is 30 arcminutes.

   4. Proximity finds objects near to a list of positions. You give the list, either by pasting into the textbox or by uploading a file. You can optionally specify a maximum separation in which to search.

2. When you have finished entering all your constraints, click Submit Request. The tool will return only the objects you asked for, in the output format you specified.

3. You will see your results in a new window.

4. If you would rather use SQL to search by position, change your query so that you use one of the position functions, either dbo.fGetNearbyObjEq(ra,dec,radius) or dbo.fGetObjFromRect(ra1,ra2,dec1,dec2). Specify the function in the FROM block, and be sure to check that the object IDs are the same in the WHERE block.

You can also apply more constraints to your search, searching for positions or magnitudes. You can use an SQL search (opens in new window) to request other constraints, to give you any type of quasar sample that you want. See the SQL Tutorial for more on how to use SQL.

Next: Search by redshift

Back to Cooking with Sloan main page
Back to Help main page
Contact Help Desk