Contents of Archive

The ASCA data is archived in a target-oriented (strictly speaking, observation-oriented) structure, i.e., all the data produced from an observation is put into a directory --- although some exceptions exist for observations in very early epoch.

Each dataset includes telemetry data, data products (event files, images, energy spectra, light curves, etc.), and calibration data. ISAS provided the telemetry and calibration data, and ASCA data processing center in ADF (Astrophysics Data Facility) at NASA/GSFC reproduced the data products. Files are put in the directories listed below.

telemetry/ Telemetry files
unscreened/ Event files without any screening
screened/ Event files with a default screening
images/ Images and exposure maps.
spectra/ Energy spectra and response matrices
lcurves/ Light curves
aux/ Miscellaneous information, such as description of the archive, house-keeping data, and filter files.
calib/ Calibration data used in the processing

Highlights of Revision 2

Revision 2 is the latest version of data processing (since June 1997). Here, we show a brief summary of new features of revision 2 data processing and its products. Details on the contents are given in ASCA Getting Started Guide for Revision 2 Data : Highligths of Revision 2 are in section 1, and naming conventions and descriptions of all the files in the archive are given in the section 4.

  • Images in the archive are corrected for exposure, and the images for all event files from like detectors are summed up.
  • The automatic source detection program picks up the bright spots in the ASCA image, and energy spectra and light curves for each source are extracted.
  • HTML documents on the observation and the processing are produced.
  • Numerous "raw" files (or "science fits") are thrown away. "Unscreened" event files, which are basically the combination of "raw" files, are the current starting point of data reduction.

Query System

Science data and proposal is searchable at Astro Query at DARTS. The table description is here.

Metadata Tables

These are metadata of ASCA observations. The table description is here.


These calibration files are necessary to analyze ASCA data. Please see also the ASCA Analysis page for more details.

Last Modified: 18 May 2023