File Name Conventions

Most ASCA file names have one of two forms. The first is a date and time based format used for telemetry files and files derived directly from them. The other is a sequence number based file name, with additional components describing the conditions under which the data were taken. Most files have the sequence number based format.

Date-Based File Names

1. A prefix - `fa' for attitude files and `ft' for all other files.
2. The starting date of the data in the file in `yymmdd' format.
3. The starting time (UT) of the data in the file in `hhmm' format.
4. The ending time (UT) of the data in the file, also in `hhmm' format. Note that files may go past midnight, so the ending time may be smaller than the starting time.
5. An extension specifying the file type (see the descriptions of the individual files).

Sequence Number Based Filenames

1. The string `ad' which stands for "Astro-D". This is the pre-launch name for ASCA.

2. The eight-digit sequence number unique to this observation. Some of its digits have special significance. The first digit of the sequence number gives the target type as follows:
   • '1' - Calibration and Targets of Opportunity.
   • '2' - Stars
   • '3' - Cataclysmic Variables
   • '4' - X-Ray Binaries
   • '5' - Supernova Remnants and Galactic Diffuse Emission
   • '6' - Galaxies
   • '7' - Active Galactic Nuclei
   • '8' - Clusters of Galaxies and Superclusters
   • '9' - X-Ray background, Deep Survey, and other
   For non-calibration sequences, the second digit gives the AO number, with `0' used for PV phase data. Multiple observations for the same proposal will generally have sequence numbers which differ only in their second-to-last digit.

3. Instrument name. This can be one of `s0', `s1', `g2', or `g3' for SIS0, SIS1, GIS2, or GIS3, respectively. Also 'sis' is used to refer to data which combine SIS0 and SIS1, and 'gis' is used to refer to data which combine GIS2 and GIS3.

4. Index. This is a three digit number mostly used to keep file names unique. In general a file will have the same index as the file from which it was derived. For image and source list files, the index refers to the number of pixels across the image.

5. Observing mode. This is a two digit code specifying the instrument mode as follows:
   • 01 for SIS Faint mode data.
   • 02 for SIS Bright mode data.
   • 12 for SIS Bright2 mode data.
   • 03 for SIS FAST mode data.
   • 70 for GIS PH mode data.
   • 71 for GIS MPC mode data.

6. Bit-rate. This is the single character `h', `m', or `l' for high, medium or low bit-rate, respectively. Some of the data products such as images, spectra, and binned light curves may combine data of different bit-rates, and therefore do not have a bit-rate designation.

7. Source number. Products such as spectra and light curves are extracted for individual sources within the field of view of the instruments. The source number is a single digit separated from the rest of the file name by an underscore. Source `_0' is used to refer to the entire field of view with all detected sources excluded.

8. Extension. File names will generally have additional characters separated by an underscore or dot which indicate the file type. See the descriptions of individual file types for more information.