ROSAT Status #126. New Software and Error in RDF HRI ancilliary file

[REQUEST@rosat.gsfc.nasa.gov]

		ROSAT Status Report # 126
		       June 5 1995



1) New software in the ESAS package.

The ESAS package is the Extended Source Analysis Software prepared by Steve 
Snowden. 
Software is now available to cast exposure maps and model particle-background
maps for HRI observations.  Software to mosaic multiple exposures in a region
is also now available.  As with previous programs in the ESAS package, 
the new ones are 
stand-alone FORTRAN 77 routines relying on FITSIO to access the data in 
observation data sets.  The new software has been extensively used locally 
but is still in beta-site testing, so any bugs or suggestions should be 
reported to Snowden (snowden@lheavx.gsfc.nasa.gov).  The software, along with 
a cookbook (cookbook.tex) and README file, is located in the legacy anonymous 
ftp area:

rosat/software/fortran/sxrb


2) Error in the RDF HRI ancillary data file, event rate extension.

Certain of the entries in the EVRATE table (EXTNAME='EVRATE' in the
ancillary data file) in RDF HRI data sets are in error, the most
obvious being the primary count rate.  This error occured in the fits
conversion and is restricted to the event rate table.  Check the RDF file 
header keyword RDF_VERS to determine the version of RDF software in 
processing. The affected data sets will be corrected before entering the 
archive but will not be generally redistributed on tape to GOs.  

The data for generating the EVRATE extension (in the HRI Ancillary FITS
file) comes from the *.SEC files which are created by SASS in the SEQuence
directory. Starting with SASS7_2, a new field (ASPECT_STATUS) was added
to the *.SEC files. Because this new field was added in the middle of
the data record of the *.SEC files, the column labels (TTYPEn) in the
EVRATE extension of the ANCillary FITS file as given in the extension
header no longer matched the data in the corresponding columns of the
data array.

Due to the order in which variables were read in from the SASS *.SEC files 
and written out to the EVRATE extension, the SAADB_RT data were left out 
and were not included in the ANCillary FITS files, and the MASKED_OUT data 
were replaced by the Earth-satellite-target angle.

The correspondence between the column label and the data in that column
is given in the table below:


                                  Column in
                Header label      old ANC
  Column #      in old ANC        EVRATE extn
  in old ANC    EVRATE extn       actually
  EVRATE extn   (TTYPE)           contains
  -----------  --------------     ----------------------------------
    1 (ok)     'TIME'             TIME          SC clock time (sec)
    2 (ok)     'SECONDARY'        SECONDARY     Secondary science rate
    3          'PRIMARY'          ACCEPTED      Accepted X-ray rate
    4          'ACCEPTED'         ASPSTAT       Aspect status
    5 (ok)     'INVALID'          INVALID       Invalid event rate
    6 (ok)     'LIVT_COR'         LIVT_COR      Live-time correction factor
    7 (ok)     'BACKLEV'          BACKLEV       Background level
    8 (ok)     'VIEWGEOM'         VIEWGEOM      Viewing geometry
    9 (ok)     'ASPERR'           ASPERR        Aspect error
   10          'MASKED_OUT'       PRIMARY       Primary science rate
   11          'SAADA_RT'         ---->         Earth-sat-targ angle
   12          'SAADB_RT'         SAADA_RT      SAA detector rate A
   13 (ok)     'OBI_NUM'          OBI_NUM       OBI number


Datasets processed with SASS7_2 or later which were FITS-converted with 
RDF version 3.3 or earlier are affected. With the release of RDF 3.4, all 
the parameters identified in the EVRATE extension header are correctly 
incorporated in the data array.


Additionally, the value of keyword CTYPE2 in the HRI_IM1.FITS file was 
changed from DEC---TAN to DEC--TAN.