CLAMP


CLAMP is a program which calculates and lists the  CLosure  AMPlitudes
from  the  data  in  a  Merge file.  Each closure amplitude is a ratio
formed from the visibility amplitudes.  The closure amplitudes  should
be  unaffected  by  calibration  errors,  and  can  be calculated from
uncalibrated data.  For the definition of  "closure  amplitude",  see:
Readhead  et  al.,  Nature  v285,  pp137-140  (1980)  or  Pearson  and
Readhead, Ann. Rev. Astron. Astrophys. v22, pp97-130 (1984).   If  the
source  is  totally  unresolved,  the  closure  amplitudes should be 1
(within the errors).

To run the program, use the command CLAMP (defined in  VLB:LOGIN.COM).
The  program  will ask you for an input file name (the name of a MERGE
format file) and for an output file name (which may  be  SYS$PRINT  to
send  the  listing  to  the printer).  There is an option to produce a
BRIEF listing, which differs from the full listing by omission of  the
column-headings, etc.

N.B.  You need simultaneous data from at least 4 stations in order  to
calculate closure amplitudes.


                                        T.J. Pearson, 1982 December 13