AIPS HELP file for AVER in 31DEC21
As of Sun May 16 13:22:15 2021
AVER: Task to average 'BT' sorted UV data.
INNAME Input UV file name (name)
INCLASS Input UV file name (class)
INSEQ 0.0 9999.0 Input UV file name (seq. #)
INDISK 0.0 9.0 Input UV file disk unit #
OUTNAME Output UV file name (name)
OUTCLASS Output UV file name (class)
OUTSEQ -1.0 9999.0 Output UV file name (seq. #)
OUTDISK 0.0 9.0 Output UV file disk unit #.
YINC 0.0 99999. Averaging time (sec).
FQCENTER >= 0 -> center frequency axis
Task: This task will average a 'BT' sorted uv data set in time.
INNAME.....Input UV file name (name). Sort must be 'BT'.
INCLASS....Input UV file name (class). Standard defaults.
INSEQ......Input UV file name (seq. #). 0 => highest.
INDISK.....Disk drive # of input UV file. 0 => any.
OUTNAME....Output UV file name (name). Standard defaults.
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). Standard defaults.
OUTDISK....Disk drive # of output UV file. 0 => highest with
space for the file.
YINC.......Averaging time (sec). < 10. -> 10.
FQCENTER,..> 0 => Change frequency axis reference pixel to
Nchan / 2 + 1
else => do not change reference pixel
AVER: Task to average 'BT' sorted UV data
DOCUMENTOR: R. C. Walker NRAO/CV
RELATED PROGRAMS: UVSRT
AVER averages 'BT' sorted uv data bases. It is especially
useful if a large data base can be reduced in size to make it
more manageable. Care should be taken that the average time is
not so long that 'time average smearing' occurs - ie. that the
longer baselines sweep through enough uv space in an
integration interval to smear significant structure.
AVER is often used after VBFIT on VLBI data. Longer
averages are allowed at that point because relatively high
residual fringe rates due to atmosphere etc have been removed.
AVER marks the data with a time that is the weighted
average time of the data. For most purposes, this is proper,
but it can cause trouble when VLBI data is transfered to the
Caltech package. The times for data points corresponding to the
same average interval are not the same so they are treated as
separate points by TOCIT. This does not work well in the
Caltech format. To avoid the problem, the data can be averaged
in the Caltech package or AVER output can be run through the
Caltech averaging program with the same average time that was
used in AVER. The records should be properly combined in this
This sets the averaging time in seconds.
The input data base must be in 'BT' sort order. This is
not the same sort order of the UV data that is generally read
into AIPS (it is 'TB') and UVSRT must be run before using AVER.
The run time on an otherwise empty VAX 11-70 is
1.0 * (D / 100,000) minutes
where D is the number of input UV points.