AIPS HELP file for UVDIF in 31DEC26
As of Sat Feb 14 15:19:40 2026
UVDIF: Task to print differences between 2 UV disk files
INPUTS
INNAME UV data (name).
INCLASS UV data (class).
INSEQ 0.0 9999.0 UV data (seq. #). 0 => high
INDISK 0.0 9.0 Disk unit #. 0 => any
IN2NAME 2nd UV data (name).
IN2CLASS 2nd UV data (class).
IN2SEQ 0.0 9999.0 2nd UV data (seq. #).0=>high
IN2DISK 0.0 9.0 2nd Disk unit #. 0 => any
CHANNEL 0.0 9999.0 Frequency channel number.
BIF 0.0 32767.0 IF number to test.
NITER 0.0 32767.0 Max # lines printed.
0 => 10 pages
UVRANGE 0.0 UV range in kilolambda
DOACOR -1.0 1.0 > 0 include autocorrelations
OPCODE 'CLIP' print excess fluxes
'UVBX' print excess uv diffs
' ' both
APARM (1) peak ok IPOL diff
(2) peak ok pol. diff
(3) peak ok u,v,w diff
(4) peak ok weight diff
< 0 => ignore weights
(5) = 1 ignore some header
= 2 ignore all header
differences
(6) >= 1 => include diff when
both flagged
(7) > 0 => exclude crosscor
if DOACOR > 0
DOCRT -3.0 132.0 > 0 -> use CRT, else printer
> 72 => CRT width in chars
OUTPRINT
Printer disk file to save
HELP SECTION
UVDIF
Type: Task
Use: Compares two uv data sets and prints those samples which differ
by more than specified amounts in u, v, w, and/or visibility.
On all OPCODEs, the data are checked for having reasonable (and
the same) times, antenna numbers, and weights. Any which don't
are printed. Visibility comparisons are done on a correlator
basis. NOTE: this does require the two data sets to be
substantially identical although there can be differences in
which random parameters are present. It is useful for displaying
mild differences such as those caused by flagging or self-cal.
It will work with one data set compressed and the other not,
however. Compression may cause substantial differences in
weights.
Adverbs:
INNAME.....1st UV file name (name). Standard defaults.
INCLASS....1st UV file name (class). Standard defaults.
INSEQ......1st UV file name (seq. #). 0 => highest.
INDISK.....1st Disk unit #. 0 => any.
IN2NAME....2nd UV file name (name). Standard defaults.
IN2CLASS...2nd UV file name (class). Standard defaults.
IN2SEQ.....2nd UV file name (seq. #). 0 => highest.
IN2DISK....2nd Disk unit #. 0 => any.
CHANNEL....Frequency channel (use 0 for continuum)
BIF........IF number to test. 0 => 1.
NITER......Do not list more than NITER points. 0 => no more than 10
pages. NOTE: on DOCRT <= 0., the task continues through
the full data set counting "bad" points, but prints only
the first NITER points.
UVRANGE....Limit print to baselines >= UVRANGE(1) and <=
UVRANGE(2) in kilo wavelengths. 0 => all.
DOACOR.....> 0 => include autocorrelation data.
OPCODE.....If 'CLIP' program applies excess flux difference
test only.
If 'UVBX' program applies excess u,v,w difference
test only.
If anything else, does everything.
The CLIP OPCODE uses a format which omits u,v,w and uses
more places for flux and phase. The UVBX OPCODE uses
more characters for u,v,w and prints less flux
information. All others are a compromise between the
two.
APARM......APARM(1) is max. normal visibility difference (Jy) for
total intensity (Stokes I, RR, LL, VV, HH)
The real and imaginary parts are compared
separately.
APARM(2) is max. normal flux difference (Jy) for
polarization (Stokes Q, U, V, RL, LR, VH, HV)
The real and imaginary parts are compared
separately.
APARM(3) is max. normal difference in u, v, w
(wavelengths).
abs(APARM(4)) is maximum normal difference in weights,
< 0 -> ignore differences in flagging
Note that ignoring flagging cannot work with
compressed data since the data themselves are
lost, so see APARM(6) below
APARM(5) = 1 => ignore header differences in increment,
reference value, reference pixel
= 2 => also ignore axis type, number of vis
APARM(6) > 0.99 => include samples even if they are
flagged in both data sets. Samples flagged in
one of the two data sets but not the other are
always included.
APARM(7) > 0 => exclude cross correlations if DOACOR > 0
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. PRTSY now counts the lines
to be printed before printing any and asks for
permission to continue if the count > 500. This
counting is expensive so consider specifying a file
for OUTPRINT.
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.
EXPLAIN SECTION