AIPS HELP file for DIFUV in 31DEC26
As of Thu Dec 11 19:55:13 2025
DIFUV: Task to difference/divide two matching uv data sets
INPUTS
INNAME 1st input UV file name
INCLASS 1st UV file class
INSEQ 0.0 9999.0 1st UV file seq. #
INDISK 0.0 9.0 1st UV file disk #
IN2NAME 2nd UV file name.
IN2CLASS 2nd UV file class.
IN2SEQ 0.0 9999.0 2nd UV file seq. #
IN2DISK 0.0 9.0 2nd UV file disk #
OUTNAME Output UV file name
OUTCLASS Output UV file class
OUTSEQ -1.0 9999.0 Output UV file seq. #
OUTDISK 0.0 9.0 Output UV file disk #.
SOLINT 0.0 How close times must match in
minutes
OPTYPE 'DIV'=> divide, else subtract
'DDIV' => subtract and divide
DOOUTPUT -1.0 1.0 Write output file if >0 or
if DOPRINT <= 0
DOPRINT -1.0 1.0 > 0 print statistics only
DOCRT -3.0 132.0 > 0 print on terminal
OUTPRINT Text file for printed output
FQCENTER >= 0 -> center frequency axis
HELP SECTION
DIFUV
Task: This task writes out the difference, ratio or scaled ration of
two UV data sets. It does very little checking to see if they
match. One purpose of this task would be to difference the two
throws of beam-switched single-dish continuum data. Another use
would be to subtract a residual uv data set from the original to
produce a model uv data set. The division operation could be
used to produce a data set suitable for determining gains.
The task can also compute these output values and accumulate
statistics by spectral channel and polarization. These
statistics are printed in the end. The output data set may be
written or not when the statistics are accumulated.
Tables such as calibration (CL, SN), flag (FG), bandpass (BP),
etc. are not applied to either data set. The tables of the
first data set are copied to the output; the tables of the
second data set are ignored.
Adverbs:
INNAME.....First input UV file name (name). Standard defaults.
INCLASS....First input UV file name (class). Standard defaults.
INSEQ......First input UV file name (seq. #). 0 => highest.
INDISK.....First input UV file Disk drive # . 0 => any.
IN2NAME....2nd UV file name subtracted from or divided into the
first data set.
IN2CLASS...2nd UV file class
IN2SEQ.....2nd UV file sequence number.
IN2DISK....2nd UV file sequence number.
OUTNAME....Output UV file name (name). Standard defaults.
OUTCLASS...Output UV file name (class). Standard defaults.
OUTSEQ.....Output UV file name (seq. #). 0 => highest unique
OUTDISK....Disk drive # of output UV file. 0 => highest with
space for the file.
SOLINT.....Data are differenced only if times are close. SOLINT sets
that limit in minutes. 0 => 0.01 sec.
OPTYPE.....'DIV' => do division (#1 / #2)
'DDIV' => do subtraction ((#1-#2) / #2)
else do subtraction. (#1 - #2)
DOOUTPUT...> 0 => write the output data set (any DOPRINT)
else write the output data only when DOPRINT <= 0
DOPRINT....> 0 => print statistics of difference or ratio and do not
write an output file
<= 0 => write an output file
DOCRT......False (<= 0) use the line printer if OUTPRINT = ' '
else write named OUTPRINT file only.
When OUTPRINT is not blank, DOCRT=-2 suppresses the
page-feed character on page headers and DOCRT=-3
suppresses page headers and most other header
information. When OUTPRINT is blank, the line
printer will be used. LISTR now counts the lines
to be printed before printing any and asks for
permission to continue if the count > 500.
True (> 0) use the terminal interactively. The task will
use the actual terminal width as a display limit
unless 72 < DOCRT < width. In that case, the display
limit will be DOCRT characters.
OUTPRINT...Disk file name in which to save the line printer output.
' ' => use scratch and print immediately for interactive
jobs - batch jobs use OUTPRINT = 'PRTFIL:BATCHjjj.nnn'
(jjj= job #, nnn = user #). When OUTPRINT is not blank,
multiple outputs are concatenated, and the file is not
actually printed.
FQCENTER,..> 0 => Change frequency axis reference pixel to
Nchan / 2 + 1
else => do not change reference pixel
EXPLAIN SECTION