HDUVERS = 1.0.0

THIS FORMAT HAS BEEN SUPERCEDED BY HDUVERS = 1.2.0 AND SHOULD NO LONGER BE USED (see Section 2.2)

This was first format for a FITS extension to contain a PHA dataset fully-approved by the OGIP. It's detailed structure, keywords etc are described in the memo OGIP/92-007, which was also published in Legacy (Arnaud et al 1992). It should be noted that this format is commonly refered to as 'PHAVERSN = 1992a'. Essentially the FITS extension consists of a BINTABLE extension containing the PHA dataset & errors, along with 'grouping' & quality information. The following keywords/values were listed as mandatory:

• EXTNAME (= SPECTRUM) - the name (i.e. type) of the extension
• TELESCOP - the "telescope" (i.e. mission/satellite name).
• INSTRUME - the instrument/detector.
• FILTER - the instrument filter in use (if any)
• EXPOSURE - the integration time (in seconds) for the PHA data (assumed to be corrected for deadtime, data drop-outs etc. )
• AREASCAL - the area scaling factor (see Arnaud et al for details).
• BACKFILE - the name of the corresponding background file (if any)
• BACKSCAL - the background scaling factor.
• CORRFILE - the name of the corresponding correction file (if any)
• CORRSCAL - the correction scaling factor.
• RESPFILE - the name of the corresponding (default) redistribution matrix file (RMF; see George et al. 1992), supplied by BLDRSP.
• ANCRFILE - the name of the corresponding (default) ancillary response file (ARF; see George et al. 1992), supplied by BLDRSP.
• XFLTXXXX - the XSPEC selection filter descriptor, where XXXX is a number (see Arnaud et al for details).
• PHAVERSN - the OGIP version number of the FITS format in use to store the PHA data (in this case 1992a).
• POISSERR - whether Poissonian errors are appropriate to the data (see Arnaud et al for details).
• CHANTYPE - whether the channels used in the file have been corrected in anyway (see Arnaud et al for details).
• DETCHANS - the total number of detector channels available.

And the following optional keywords recommended to supply further information (primarily for the human reader):

• OBJECT - the observed object.
• RA-NOM - the nominal Right Ascension of the object (in decimal degrees)
• DEC-NOM - the nominal declination of the object (in decimal degrees)
• EQUINOX - the equinox of the above celestial co-ordinate (RA & DEC) specifications
• RADECSYS - the coordinate frame used for EQUINOX
• DATE-OBS - nominal U.T. date when integration of this PHA data started (yyyy-mm-dd). Old files may have dd/mm/yy format which will be interpreted as 19yy-mm-dd.
• TIME-OBS - nominal U.T. time when integration of this PHA data started (hh:mm:ss).
• DATE-END - nominal U.T. date when integration of this PHA data ended (yyyy-mm-dd). Old files may have dd/mm/yy format which will be interpreted as 19yy-mm-dd.
• TIME-END - nominal U.T. time when integration of this PHA data ended (hh:mm:ss).