AIPS HELP file for REFLG in 31DEC18
As of Sun Mar 18 15:20:57 2018
REFLG: Compresses flag tables
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 #
SOURCES Restrict to listed sources
CALCODE Calibrator code ' ' all
FLAGVER Flag table version
CPARM (1) Time interval in sec
IMPORTANT - see HELP
(2) flag C(2) channels
between flag groups
(3) Flag full spectrum if
fraction flagged > C(3)
(4) Flag all times if
fraction flagged > C(4)
(5) Flag all baselines if
fraction flagged > C(5)
(6) Flag antenna if
fraction flagged > C(6)
(7) =1 -> flag cross hands
if parallel flagged
=2 -> flag all polariz.
if any flagged
(8) =1,3 -> omit combination
>= 2 -> omit combination
Task: Many flagging tasks examine large amounts of data but generate
flag table entries over small ranges of time and/or spectral
channel. It may be possible to compress such tables by
combining these ranges. REFLG attempts to do this. It also
has options to delete full things if enough channels,
baselines, etc. are already flagged. After the time-frequency
operation, the task optionally takes another pass through the
flags looking for ways to combine IFs and baselines. That may
produce some gains, but is not likely to be so profitable and
can actually fail badly in some cases. You should always use
FGDIF to check that the input and output FG tables flag the
same data - then rerun REFLG if desired using CPARM(2) -
A warning about sources - if the input table has flags that
apply to a source other than those requested via SOURCES and
CALCODE, the flags may be lost if they do not specify a
specific source number > 0. Flags specifying a specific
source will be copied intact at the beginiing if they are not
in the list specified by SOURCES and CALCODE. Again FGDIF is a
good idea with a very general source list.
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.
SOURCES....List of sources to for which flags are reviewed. The
task has to list all times for a source and check them
against the flags. Preparing the list of times can be
expensive so this adverb lets you avoid sources which are
not relevant to the flag table. '*' or ' ' = all; a "-"
before a source name means all except ANY source named.
CALCODE....Also used to limit sources selected: '*' => any
non-blank, '-CAL' => only blank, ' ' => all, otherwise
FLAGVER....Specifies the version of the flagging table to be
compressed. <= 0 => highest numbered table.
A new table is always written.
CPARM......(1) Normal interval between samples (IMPORTANT) in sec.
Use a little bit less than the normal interval.
0 -> 10. This parameter can have interesting and
confusing consequences when data have been time
averaged by say UVAVG. Let us assume you have
averaged 1 second data with no flags to 5 seconds and
that the data started at time 0. Thenthe average
times will be 2, 7, 12, 17, etc seconds. But at the
end of the scan (e.g. time 20) there could be onl;y
one 1-sec record so its averaged time would be 20.
Thus to separate the 17 and the 20 one must set
CPARM(1) = 2.9 say. However, if the data input to
UVAVG already have extensive flagging, the times may
be disturbed from this nice pattern (depnding on
OPCODE in UVAVG). In this case, the possibilities
are endless and there is no simple answer to a
correct value for CPARM(1). (One might consider TIME
or even GRID in UVAVG to alleviate this issue.) The
simplest thing to do in the heavy editing case might
be to set CPARM(1) = 0.95.
The following parameters are used on the flag
information compiled by this task. That information
includes only those flags that apply to specific ranges
in time, channel, and IF and to only a single baseline.
More general flags are not included. If CPARM(i) <= 0,
the test is not performed.
(2) Flag up to CPARM(6) "good" channels located between
groups of flagged channels. Thus if we are to flag,
for example, channels 12-14, 16-20, 23-24, and 28-30
and FPARM(7)=2, then we will flag 12-24 and 28-30.
(3) If the fraction of spectral channels flagged at a
particular time and baseline exceeds CPARM(3), flag
(4) If the fraction of times flagged at a particular
channel and baseline exceeds CPARM(4), flag all
(5) If the fraction of baselines flagged at a particular
channel and time exceeds CPARM(5), flag all
baselines. Note that autocorrelations are allowed,
so the maximum number of "baselines" is (Mant *
(Mant+1)) / 2 where Mant is the maximum antenna
number. Thus the EVLA with Mant = 28 has 406
"baselines" rather than 351 when antenna 28 is in the
(6) If the fraction of baselines to a particular antenna
flagged at a particular channel and time exceeds
CPARM(6), flag all baselines to that antenna. Note
that autocorrelations are allowed, so the maximum
number of "baselines" to an antenna is the maximum
(7) = 1 -> if parallel hands flagged, flag the cross
= 2 -> if any polarization flagged, flag all
(8) The final pass through the data may be unreliable
with odd data sets (e.g. a single baseline). To
turn off the baseline combination, set CPARM(8) to 1
or 3. To turn off the IF combination, set CPARM(8)
to 2 or more.