ROSAT/HEASARC Status Report No 94:

May 19th 1994

Important Changes to Data Set Naming Conventions

Data processed before Jan 1993 was processed with the initial release of SASS, which is known as Rev 0 processing. After January 1993, a new release of SASS was used to process data; this is known as Rev 1 processing. Some improvements to SASS and the implementation of the Rationalized Data Format (RDF) for the output data heralded the start of Rev 2 processing in April 1994. One significant difference between the initial (Rev 0) processing and the later processings is the handling of follow-on observations. This change has necessitated an expansion of the file naming convention from the relatively simple scheme used during Rev 0 processing.

The observation naming scheme used during Rev 0 processing used a two-letter code + six-digit ROSAT Observation Request (ROR) number to identification a given observation sequence. For example, a typical sequence ID would be RP123456 (for a US-processed PSPC observation) or WF123456 (for an MPE-processed filtered PSPC observation). As additional data for this observation were obtained, they were combined with previously obtained data and sent to the user (and the archives) under the original two-letter + six-digit observation ID.

Starting with Rev 1 processing and continuing through Rev 2 processing, there are different naming conventions for a given observation, based on whether it's 1) an initial pointing, 2) an add-on or follow-up observation, or 3) a mis-pointing. Archive users should understand something about the change in naming convention in order to retrieve data from the archive.

The Rev 1 file naming convention is as follows:

initial pointing or mis-pointing:: 00 added to the 6 digit ROR number; Eg: RP12345600
add-on or follow-up observation:: 01...99 added to the 6 digit ROR number; (depending on the number of add-ons); Eg: RP12345601

The Rev 2 file naming convention is as follows:

initial ("normal") pointing:: NOO added to the 6 digit ROR number; Eg: RP123456N00
add-on or follow-up observation:: A01...A99 added to the 6 digit ROR number; (depending on the number of add-ons); Eg: RP123456A01
mis-pointing:: M01...M99 added to the 6 digit ROR number; (depending on the number of mis-points); Eg: RP123456M01

The Rev 2 convention shown above, which is the clearest, was not put into effect for Rev 1 datasets. Because of the potential confusion between normal observations and mis-points caused by the Rev 1 naming convention, it was decided that BOTH REV 1 AND REV 2 DATA WILL BE ARCHIVED USING THE REV 2 NAMING CONVENTION. For example, a data set that was processed by Rev 1 SASS and distributed to the PI with the dataset ID RP12345601 will enter the archive as RP123456A01.

How will this effect archive users?

Unlike the Rev 0 data sets, in which the entire observation was "packaged" under one observation ID (i.e., RP123456), each individual "pointing" is packaged under an individual name for Rev 1 and Rev 2 processed data. For example, suppose there is an observation of the galactic center having an ROR of 123456, which is made in 2 pointings (initial pointing + 1 add-on). This data will enter the archive as 2 discrete data sets, RP123456N00 and RP123456A01. To get the entire observation, the archive user will need to retrieve both datasets (RP123456N00 and RP123456A01).
Because the Rev 1 and Rev 2 data sets have different output file formats (the Rev 2 uses the RDF format, while the Rev1 did not), a given observation ID may be archived as a Rev 1 processed data (in the old-style, non-RDF format) at one time and then later (after reprocessing) the data set will be replaced by an RDF version.

We regret the inconvenience caused by the change in naming scheme, but point out that as data are re-processed, all REV 0-processed data will be replaced by REV 2 versions. This means that eventually all data in the ROSAT archive will follow the REV 2 naming convention.

Questions about data in the US Public Archive should be sent to Dr. M. Corcoran at the address below.

Special Note About MPE-Processed Hri Archival Data

HRI FITS-formatted datasets produced by MPE have filenames ending in ".mt" (rather than ".tfits" or ".ifits", which is used for the PSPC data produced by MPE). Users should rest assured that these data are in the standard MPE EXSAS FITS format similar to that used for the PSPC, only the extension name has been changed (to protect the innocent?). Previous versions of the user guide "archive_intro.txt" (available from the heasarc.gsfc.nasa.gov anonymous ftp account) were written before we received any HRI datasets from MPE and were under the (mis)conception that the ".ifits" and ".tfits" file extensions were to be used for both PSPC and HRI data. This was not the case, so the recent version of the archive user's guide (available in rosat/doc/archive on heasarc.gsfc.nasa.gov) has been corrected to reflect this reality.

ROSAT CD Rom Volume II

A sneak preview of volume II of the ROSAT Images CD ROM can be found on the WWW under

http://heasarc.gsfc.nasa.gov/docs/rosat/cdroms/rosatcdroms.html

This CD ROM, produced by the HEASARC and US ROSAT Data Center, will be distributed at the Minneapolis AAS meeting. Copies of Volume I and II can be obtained by sending your mail address to ksmale@lheavx.gsfc.nasa.gov

ROSAT Catalog

The US ROSAT Data Center in collaboration, with the HEASARC, is currently working on rationalizing the various ROSAT data base tables into a single observation catalog. The current confusion of multiple tables with inconsistent information results from the fact that we receive the information from different sources (MPE, University of Leicester, and the US processing team). By combining all these tables into a single database, we hope to provide a much cleaner interface to gather information on the status of a particular observation and the resulting data. This rationalization is a major effort that will take several months. We hope to have it complete in the July/August 1994 timeframe. Until then, please be patient and tell us of any inconsistencies you find in the current tables. Comments, questions or complaints should be sent to:

Dr. Mike Corcoran

US ROSAT PROJECT/HEASARC

Goddard Space Flight Center

Greenbelt, MD 20771

corcoran@barnegat.gsfc.nasa.gov

HEASRC::CORCORAN