AIPS HELP file for UVCOP in 31DEC24
As of Wed Apr 24 14:02:25 2024
UVCOP: Task to copy selected times and channels of uv data.
INPUTS
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 #.
SELBAND Bandwidth to select (kHz)
SELFREQ Frequency to select (MHz)
FREQID Freq. ID to select. 0=> all
BCHAN 0.0 9999. First channel selected.
ECHAN 0.0 9999. Last channel selected.
BIF 0.0 100.0 Lowest IF number 0=>all
EIF 0.0 100.0 Highest IF number 0=>all
SOURCES Source list
QUAL -10.0 Source qualifier -1=>all
UVRANGE Annulus in uv plane selected
(thousands of wavelengths)
TIMERANG Timerange:
1-4 = start day,hr,min,sec
5-8 = end day,hr,min,sec
ANTENNAS Antennas to copy 0=>all
BASELINE Baselines with ANTENNAS
SUBARRAY 0.0 Limit copy to one subarray
0 => all.
FLAGVER -1.0 FG table to apply to data
<= 0 => do not apply
UVCOPPRM Flags:
1 > 0 => keep flagged data
2 > 0 => drop subarray info
3 = 0 => copy xc and ac data
= 1 => copy only xc data
= 2 => copy only ac data
of antennas, named in
antenna list. Baseline
list must be zero.
4 unused
5 => flag data with weights
below this limit
6 = 1,3 -> do NOT flag TY/SY
= 2,3 -> do NOT flag SN
7 = extend copy of tables
by UVCO(7) min, 0 -> 15
8 = Holography data: do not
scale holo's by freq.
SRCALIAS Names of holography sources
(HOLORASTER always used)
NCOUNT If UVCOPPRM(3) = 2 then
NCOUNT is the approximate
ratio of AC to XC in file.
FQCENTER >= 0 -> center frequency axis
BADDISK Disks to avoid for scratch
HELP SECTION
UVCOP
Task: This task will copy a subset of a uv data base selected by time
range, IF, frequency channel and subarray. It can apply a flag
table to the data and is able to apply up to 600000 flags to a
time (10 times the usual limit). It also removes any random
parameters called REMOVED which use up disk space for no good
reason. By default, UVCOP will delete all fully flagged samples,
and it can be used to delete data with weights below a limiting
value. It may also be used to wipe out all distinctions between
data from different subarrays.
When selecting a FREQID > 1 the FREQID in the output file will be
changed to 1. The task will loop over FREQID if none is
specified. When selecting a single subarray or removing the
distinction between subarrays, the output subarray will be
numbered 1.
Adverbs:
INNAME.....Input UV file name (name). Standard defaults.
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. #). 0 => highest unique
OUTDISK....Disk drive # of output UV file. 0 => highest w room
SELBAND....Bandwidth of data to be selected. If more than
one IF is present SELBAND is the width of the
first IF required. Units = kHz.
SELFREQ....Frequency of data to be selected. Units = MHz.
FREQID.....Frequency identifier to select (you may determine
which is applicable from the OPTYPE='SCAN' listing
produced by LISTR). If either SELBAND or SELFREQ
are set, their values overide that of FREQID.
However, setting SELBAND and SELFREQ may result in
an ambiguity. In that case, the task will request
that you use FREQID. (.le. 0 => all). If you select
data with the FREQ adverbs UVCOP will renumber the
FREQID in the output file to 1, i.e. you can set
FREQID to the default value for all subsequent
operations on the output file.
BCHAN......First frequency channel selected. 0 => all or cont.
ECHAN......Last channel selected. 0 => all (or continuum).
BIF........First IF to copy. 0=>all.
EIF........Highest IF to copy. 0=>all higher than BIF
SOURCES....List of sources to copy. '*' or ' ' = all; a "-"
before a source name means all except ANY source
named.
QUAL.......Only sources with a source qualifier number in the
SU table matching QUAL will be used if QUAL is not
-1.
UVRANGE....Range (min, max) of projected baselines to include;
values are in 1000's of wavelengths at the
reference frequency in the input data.
0,0 => all baselines.
TIMERANG...Timerange specified: 1-4 = start day,hr,min,sec
5-8 = end day,hr,min,sec
start time = 0 => do from beginning; end time
=0 or <= start time => do to end of data
ANTENNAS...A list of the antennas to be copied. All 0 => all.
If any number is negative then all antennas listed are NOT
to be copied and all others are.
BASELINE...Baselines between antennas named in ANTENNAS and those
named in BASELINE are selected.. There are four possible
combinations of ANTENNAS and BASELINE:
1. ANTENNAS = 0; BASELINE = 0.
All possible baselines are selected.
2. ANTENNAS <>0; BASELINE = 0.
a)All ANTENNAS > 0
Baselines including an antenna in the ANTENNAS list
are selected;
b)Some ANTENNAS < 0
All baselines NOT including an antenna in the ANTENNAS
list are selected;
3. ANTENNAS = 0; BASELINE <> 0.
a)All BASELINE > 0
Baselines including an antenna in the BASELINE list
are selected;
b)Some BASELINE < 0
All baselines NOT including an antenna in the BASELINE
list are selected;
4. ANTENNAS <> 0; BASELINE <> 0.
a)All ANTENNAS>0 and all BASELINE>0
Baselines between antennas named in ANTENNAS and those
named in BASELINE are selected.
b)Some ANTENNAS<0 .OR. some BASELINE<0
Baselines between antennas named in ANTENNAS and
those named in BASELINE are DE-selected, all others
are selected.
SUBARRAY...> 0 => copy only specified subarray, renumbering it as
number 1. <= 0 => copy all subarrays and do no
renumbering.
FLAGVER....IF > 0, apply flag table version FLAGVER to the data
(permanently) flagging the data. Fully flagged records may
be dropped but only if UVCOPPRM(1) <= 0.
Note: FLAGVER = 0 means no flagging here.
UVCOPPRM...UVCOPPRM(1) > 0 tells the program to copy fully flagged
data, otherwise they are dropped.
UVCOPPRM(2) > 0 tells the program to drop all distinctions
between subarrays (not advised).
UVCOPPRM(3) tells the program which type of data to copy;
0 => copy all data types; 1 => copy only cross-power
data; 2 => copy only total-power data.
UVCOPPRM(4) > 0 keeps you informed about UVCOP progress,
listing every 10,000th visibility and associated time
stamp.
UVCOPPRM(5) => used to set a lower limit for allowed
weights. Any data with weights < UVCOPPRM(5) will be
flagged and if the whole record ends up flagged it
will be copied only if UVCOPPRM(1) > 0. ** WARNING:
THIS OPTION CHANGED 21-JUL-2011. It used to omit
records if all weights in all channels and IFs were
less than UVCOPPRM(5) but did not flag anything. Now
it flags all low weights and passes the data on with
the flags unless all correlators are now flagged.
UVCOPPRM(6) >0 => if flagging is applied to the UV data,
it is applied by default to SN, SY, and TY tables. To
stop that, set UVCOPPRM(6) as a bit pattern - values 1
and 3 => do NOT flag SY/TY tables, values 2 and 3 =>
do NOT flag SN tables.
UVCOPPRM(7) => Tables are copied from the specified begin
time minus UVCOPPRM(7) minutes to the specified end
time plus UVCOPPRM(7) minutes. This is to include CL
table and SN table points for interpolation purposes.
0 -> 15 minutes. If you do not want this extension,
set UVCOPPRM(7) less than zero or to something very
small like 0.0001.
UVCOPPRM(8) > 0 => this is holography data - do not scale
the u,v,w of the holography sources for frequency
SRCALIAS...Source names used for holography: 'HOLORASTER' is always
added to the list so normally SRCALIAS=' '.
NCOUNT.....Is the ratio of AC data to XC data. Is used when
UVCOPPRM(3) = 2 to create an output file that is
approximately the correct size, rather than one
which is far too big.
FQCENTER...> 0 => Change frequency axis reference pixel to
Nchan / 2 + 1
else => do not change reference pixel
BADDISK....The disk numbers to avoid for scratch files (sorting
N---------------------------------------------------------------
UVCOP: Task to copy a subset of a uv data base.
RELATED PROGRAMS: UVLOD, UVFLG, UVSRT, INDXR
PURPOSE
UVCOP copys a subset of a uv data set. The subset is specified by a
timerange and frequency channel. The program also can be used to make
an unmodified copy of a uv data base. Additional options determine
whether or not fully flagged data are copied and subarray information
retained.
COMMENTS
BCHAN, ECHAN:
These adverbs allow selecting frequency channels in a uv
database. The channel numbers are one-relative to the first channel
contained in the data base; zeros for these values indicate that all
data are to be copied.
ANTENNAS, BASELINE
Antennas to be copied are specified in array ANTENNAS and/or BASELINE.
If any antenna number is negative the absolute value will be used and
all antennas listed will be deselected, i.e. the described operation
will be done on all OTHER antennas. If both ANTENNAS and BASELINE have
non zero values, then a set of baselines are specified between the
antennas listed in the one and those listed in the other. It either
array contains a negative, then all specified antennas or baselines are
omitted, otherwise the specified ones are copied.
If UVCOPPRM(3) = 2, then auto correlations of antennas, named in ANTENNA
or in BASELINE, are copied. In this case, it is best if one of ANTENNA
and BASELINE is set to zero; otherwise unexpected results can occur (see
the last example below).
Examples:
If ANTENNAS = 1,2,3 and BASELINE = 4,5 then baselines
1-4, 2-4, 3-4, 1-5, 2-5 and 3-5 are selected.
If ANTENNAS = -1,2,3 and BASELINE = 4,5 then ALL baselines
EXCEPT 1-4, 2-4, 3-4, 1-5, 2-5 and 3-5 are selected.
If ANTENNAS = 1,2 and BASELINE = 0 and UVCORPRM(3) =2 then
1-1 and 2-2 will be copyed.
But
If ANTENNAS = 3,4 and BASELINE = 1,2 and UVCORPRM(3) = 2 then
1-1 and 2-2 will be copyed and not 3-3 and 4-4.
UVCOPPRM:
UVCOPPRM(1) is a logical flag (> 0.0 => true) telling the task to
copy fully flagged visibility records. If the data are heavily
flagged, the default can produce a significantly smaller data file.
UVCOPPRM(5) can be used to flag all data with weights below a limiting
value.
UVCOPPRM(2) is a logical flag (> 0.0 => true) telling the program
to remove all distinctions between subarrays. The subarray number is
dropped, the times are corrected by 5 days (times the subarray number
- 1), and only antennas file # 1 is copied. Note: this can confuse
two non-identical antennas each numbered "n". It can also cause a
loss of the true date and frequency of observation. Do not run UVFIX
on a file produced with this option (without considerable thought).
EXECUTION TIMES:
The run time in an otherwise empty VAX is about 12 seconds
for each 10,000 uv data points.