[daip] UVFLG

[Lynn D. Matthews]

I am experiencing some peculiar behavior with UVFLG when I try to flag on
elevation.

I have a multi-source dataset with 2 IFs, one stokes. I find that in some
cases when I have APARM(4) set to a non-zero number, the program flags
data for a source even when there are no data in the elevation range
specified.

For example, I have a source with no data below 10 degrees and no data
above 88 degrees. When I apply the FG table created by UVFLG
I get the following different results for that source depending on my
UVFLG inputs:

aparm(4)=5, aparm(5)=10: loses 6002 out of 35615 vis.

aparm(4)=-10, aparm(5)=10: loses 24404 out of 35615 vis.

aparm(4)=0, aparm(5)=10: creates FG table with bogus entries, so that
all vis. still remain when FG table is applied

aparm(4)=88, aparm(5)=89: no FG table created; tells me "Nothing was added
to FG table 1"

These results also change depending on whether I set to flag only one IF
or both IFs.

aparm(4)=-10, aparm(5)=10, bif=1, eif=1 loses 1 out of 35615 vis.

My UVFLG inputs are appended below.

Lynn Matthews

AIPS 2: UVFLG:  Task to Flag selected UV data on disk.
AIPS 2: Adverbs     Values                 Comments
AIPS 2: ----------------------------------------------------------------
AIPS 2: INNAME     'BG118H'                UV data (name).
AIPS 2: INCLASS    'FOR FG'                UV data (class).
AIPS 2: INSEQ         2                    UV data (seq. #).  0 => high
AIPS 2: INDISK        4                    Disk unit #.  0 => any
AIPS 2: INFILE     *all ' '                Text file name.
AIPS 2: SOURCES    *all ' '                Sources selected/deselected
AIPS 2: SUBARRAY      0                    Subarray number 0=>all.
AIPS 2: SELBAND      -1                    Bandwidth to flag (kHz)
AIPS 2: SELFREQ      -1                    Frequency to flag (MHz)
AIPS 2: FREQID       -1                    Freq. ID to flag. -1=>all.
AIPS 2:                                    0=> first Freq. ID.
AIPS 2: TIMERANG   *all 0                  Time: start day,hr,min,sec
AIPS 2:                                          stop day,hr,min,sec.
AIPS 2: BCHAN         1                    First frequency channel
AIPS 2: ECHAN         0                    Last channel 0=>all
AIPS 2: BIF           1                    First IF 0=>1
AIPS 2: EIF           2                    Last IF 0=>all
AIPS 2: ANTENNAS   *all 0                  Antennas
AIPS 2: BASELINE   *all 0                  Baselines with ANTENNAS
AIPS 2: STOKES     ' '                     Stokes' parameters
AIPS 2: FLAGVER      12                    Flag table version number
AIPS 2:                                       Used w single-source too
AIPS 2: APARM         0           0        Clip on ampl. and weight
AIPS 2:               0         -10        (single source data only)
AIPS 2:              10        *rest 0     1:lower limit of amplitude
AIPS 2:                                    2:upper limit of amplitude
AIPS 2:                                      0 => use defaults
AIPS 2:                                      sign is significant!
AIPS 2:                                    3:limit of weight
AIPS 2:                                    The data with ampl. outside
AIPS 2:                                    of a given range or  weight
AIPS 2:                                    less the given value are
AIPS 2:                                    flagged (unflagged)
AIPS 2:                                         Elevation flagging
AIPS 2:                                    4:elevation lower cutoff deg
AIPS 2:                                    5:elevation upper cutoff deg
AIPS 2:                                    6:Factor of suppression of
AIPS 2:                                      spurious fringes caused by
AIPS 2:                                      pulse cal when fringe
AIPS 2:                                      rate close to zero.
AIPS 2:                                      It must be >1
AIPS 2:                                      0 => do not flag due to
AIPS 2:                                        this reason
AIPS 2:                                    7:>0 => Print source, time,
AIPS 2:                                       baseline,  U,V of expected
AIPS 2:                                       zero fringe rate (U=0)
AIPS 2:                                      0 => do not print
AIPS 2:                                    APARM=0 => flagging(unflag.)
AIPS 2:                                    does not depend on APARM
AIPS 2: OPCODE     'FLAG'                  'FLAG','UFLG'
AIPS 2: REASON     'BELOW 10 DEG'          Reason (24 char.)
AIPS 2: BDROP         0                    First vis. no. to flag
AIPS 2:                                      (not with flag tables)
AIPS 2: EDROP         0                    Last  vis. no. to flag
AIPS 2:                                      (not with flag tables)
AIPS 2: DOHIST       -1                    > 0 -> add to history