Archive contents

Initially, data obtained by ASCA are processed at the Goddard Space Flight Center (GSFC) for distribution to principal investigators. Once they become public, the data enter the ASCA public data archive which also resides at GSFC. The UK ASCA archive contains a subset of the archive at GSFC. It includes the event files, quick-look images and housekeeping data obtained from the ASCA GIS and SIS instruments for each pointed observation. All the files in the UK ASCA archive have been generated with the latest (REV2) processing software.

The data are stored in the standard FITS (Flexible Image Transport System) format and also as GIF (Graphic Interchange Format) files. All FITS files are compressed using the gzip compress utility. Three sets of data products are available for each observation sequence;

• the UNScreened data files (unfiltered event files)
• the SCReened data files (filtered event files)
• the AUXiliary files (miscellaneous files produced in processing, the most useful of which are the filter files).

The quick-look images for each detector type (GIS and SIS) are available on-line in FITS and GIF format, and in several energy bands. The processing log files are in HTML format, and come bundled into a single tar archive per observation.

In addition to the data archive (``ASCAPUB"), the LEDAS provides access to several other ASCA database tables. Table 1 is a list of these ASCA databases as of March 2000. An up-to-date list of the ASCA databases currently available can be found at:
http://ledas-www.ledas.ac.uk/asca/asca_databases.html.

Table 1: ASCA Database Tables at LEDAS

Database	Description
ASCAAO	ASCA proposals
ASCASIS	SIS Source catalog
ASCAMASTER	Master observation log
ASCAPUB	Public data archive
ASCALOG	Observation log