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