Accessing remote catalogues

CURSA provides some limited facilities for accessing remote catalogues held on-line at various astronomical data centres and archives around the world. You can select a subset from one of these catalogues and save it as a catalogue on your local computer using either catremote or the catalogue browser xcatview¹⁵ (see Section ). catremote and xcatview provide the same functionality for accessing remote catalogues, though xcatview is slightly more convenient to use. Currently the only sort of selection which is permitted on remote catalogues is to select all the objects in the catalogue which lie within a given angular distance from a given point on the celestial sphere (thus, the selection corresponds to the `circular area' or `cone search' option of catselect, see Section ). The remote catalogues are accessed via the Internet and obviously the option will only work when CURSA is being run on a computer with suitable network connections. If you are using CURSA at a normal Starlink node then remote access will usually be available. Conversely (and obviously) if you are using it on a stand-alone Linux PC without network connections then remote access will not be possible.

The remainder of this section refers to catremote. However, all the material, apart from the specific instructions for running catremote, is equally applicable to accessing remote catalogues using xcatview. Section  describes how to run catremote and Section  how to configure it to specify the list of remote catalogues which are accessible. Strictly speaking this information is all that you need to know in order to use catremote. However, it is useful if you understand various peculiarities and shortcomings which are contingent on the way that the remote access operates; subsequent sections provide the details.