From hmay Mon Dec  6 14:18:01 1993
To: wwilson, nkilleen, rsault
Subject: integration time/weights
Content-Length: 3107
X-Lines: 88


Neil does not like the use of weightarray(1) for passing the single
baseline value to rpfitsout, so I've reverted to using a new common 
variable.

Neil would like to call this intbase, not weightpar and redefine it
as follows:

In the RPFITS FILE:
  In file header 
          INTTIME is basic unit of integration for the whole
                  file. (as before)
          NAXIS2  =3 if weight array is included
                  =2 otherwise.
  With each baseline a new random parameter 
          INTBAS is the total integration time in secs for the baseline. 
                 If NAXIS2=3, this will be ignored
                 If NAXIS2=2, a non-zero value will be interpreted as 
                              the inttegration time for this baseline - 
                              to be multiplied in AIPS by INTTIME.


In rpfitsout :
--------------
  pcount - an internal variable set in data statement to 10 instead of
           9 as before.
  PCOUNT - in file header = number of random parameters
  NAXIS2 - in file header = number of 'axes' of data. Normally 2 or 3 - real, 
           imag and optionally, weight.
  write_wt argument passed to rpfitsout. 
           If true, will write weight array to file, otherwise not.
  intbase  real number in rpfits common.  This is used to 
           pass a single integration time to be written to the RPFITS file
           with to this baseline.
  INTBAS   name of the random parameter in which intbase is stored in the
           RPFITS file. 

  writing file header:
     PCOUNT = pcount
     if (write_wt) NAXIS2 = 3
     else          NAXIS2 = 2   

  writing random parameters with each baseline:
     INTBAS = intbase

  writing data :
     if (write_wt) write weight array to buffer
     else          weight array not written (array two thirds the size)

In rpfitsin :
-------------
  PCOUNT - in file header = number of random parameters
  pcount - an internal variable used to store PCOUNT
  NAXIS2 - in file header = number of 'axes' of data. Normally 2 or 3 - real, 
           imag and optionally, weight.
  write_wt logical internal variable derived from NAXIS2. 
  INTBAS   name of the random parameter in which intbase is stored in the
           RPFITS file. 
  intbase  real number in rpfits common. Used here for temporary storage
           of INTBAS. 

  reading file header:
     read PCOUNT  (in new RPFITS files will be 10, in old files will be 9)
     read NAXIS2
     if (NAXIS2=3) n_complex = 3
                   write_wt = .true.
     else          n_complex = 2
                   write_wt = .false. 
 
  reading random parameters with each baseline:
      intbase = 0
      if (PCOUNT=10)
          intbase = INTBAS
      else if 9 intbase = inttime      

   reading data:
      if (NAXIS2=3) read weight array into buffer
      else 
          if (intbase != 0) set whole weight array to intbase
          else              set whole weight array to 0
                            
Is that better?

Henrietta