The observation catalogue (obscat) is a fits file containing event file names and other pertinant information about the files, such as on-time, datamode,... The user can specify the items to be included in the obscat, and there are a set of built in defaults for the ASCA mission.
The data files must all be contained in the same directory, the data directory. The obscat is constructed by doing a directory listing on the this directory, using a mission dependant regular expression for the file names. There is also the provision for user supplied regular expressions.
Currently the catalogue is designed primarily for the ASCA mission. It assumes the naming conventions of FRFREAD for the Event, HK and GTI files. Although the catalogues are limited to the contents of one directory, the HK files can be kept in a separate directory.
To make a new catalogue, use the command
xsel > make obscat
A catalogue will be made in the current work directory with the default name xsel_(inst).cat, where (instru) is s0, s1, g2, g3 for the ASCA mission. It is saved when the Xselect session is exited, regardless of whether the rest of the session is saved.
To view the contents of the catalogue, use the command
xsel > show obscat
To read in data from the catalogue, use the command
xsel > choose
If you have a catalogue with the default name corresponding to the currently selected instrument, then choose and show will act on that catalogue automatically.
To apply selection criteria to the current catalogue to produce a new catalogue, use the command
xsel > select obscat
This selection overwrites the previous catalogue at present, so you may want to save it, using the command
xsel > save obscat
To read in a previously saved catalogue, use the command
xsel > load
Finally, if you want to read in data without the aid of a catalogue, there is the command
xsel > read
There are several other functions which give more information about the data. To view the contents of the Event, HK or GTI files that have been entered, use the command
xsel > show file
To see the data read in, use the command
xsel > show data
Finally, to clear the data use
xsel > clear data