Program:      RDBPHF

Purpose:      Add BPHF information to an existing IRDS

Category:     IRAS

File:         rdbphf.c

Author:       P.R. Roelfsema

Keywords:

    IRSET=    Name of input IR data set [quit]

***   DIR=    Give directory containing BPHF for sop/att xxx/xxx [skip]

              If an alternative set of BPHF files are to be used
              the user can specify a directory (DIR=) where they can 
              be found. In this case the program will ask a file number
              for each file to be read from this directory.

              FILE= Give filenumber for sop/att xxx/xxx [1]

              If a file specified like this does not contain
              the BPHF for the given sop/att, the program will continue
              to the next snip.

***  FULL=    Full error information ? [ N ]


Description:

                RDBPHF reads data from the Super Boresight Pointing
              History Files and adds these data to the IRDS specified
              with IRSET=. For each satcal tick for all sinps in the
              IRDS the positioning information longitude, latitude and
              twist angle between SRLAT north and telescope Z-axis
              (all in the sunreferenced ccordinate system relevant
              for the snip) are added to the header (descriptor items
              SRLAT, SRLON and TWIST).
                For each snip also the longitude (LNGSUN) of the sun at the
              beginning of the snip (at epoch 1983.5) and the rate of change
              of the solar longitude (SUNRATE) are added to the header.
                The error information (errors in SRLON and SRLAT, descriptors
              SIGSRLON and SIGSRLAT respectively) can be added to the IRDS
              header in two ways; only the average errors over each snip
              (FULL=N, the default), or for each tick the appropriate
              error (FULL=Y). Note that using FULL=Y will increase the
              size of the header by approximately 40%.
                 After RDBPHF (with FULL=N) the IRDS header will be very BIG!
              For e.g. band 1,2 and LRS data the header will have the same
              size as the image data.

Updates:      Sep  4, 1990: PRR, Document created.
              Nov 15, 1990: PRR, Version 1.0 in system.
              Mar 19, 1992: HB,  New interface to irds_enquire_snip
              Sep 11, 1992: PRR, Added DIR=/FILE=