Documentation on uvedit

Task: uvedit
Purpose: Editing of the baseline of a UV data set.
Categories: calibration, uv-data

     UVEDIT is a MIRIAD task which allows baseline editing of a UV
     data set.  As a result of the editing, certain header variables
     of the data set are changed.  The headers `corr' and `wcorr'
     are always changed since they are the data themselves.  The
     headers `coord(2)' are the baseline coordinates and, as a
     result, are also always changed (except with the option nouv).
     The UV variable headers `lst', `ut', and `time' are updated
     whenever a time offset is entered.  The headers `ra', `dec',
     `obsra', and `obsdec' are changed whenever a positional
     correction is entered with the ra or dec input.  Finally,
     antenna coordinate corrections will cause the header `antpos'
     to be corrected.

     NOTE: There can be NO select keyword for this routine!  If
     one includes the select option, then data that is not selected
     will not be copied!

Key: vis
     The name of the input UV data set.  At least one file name must
     be supplied.  Up to 50 visibility files are currently allowed.

Key: source
     The name of the source to apply corrections to if more than
     one source is present in a UV data set.  All UV data that does
     not correspond to the input source name is copied without being
     edited.  If this keyword is not set (the default), then all
     sources are edited.  Only one source name may be input.
     Note: it probably doesn't make sense to use this keyword with
     any other options except the ra and dec keywords.  If any other
     editing (except ra/dec) is requested along with this keyword,
     a warning message will be issued but the editing will proceed.

Key: apfile
     The name of a file that contains the absolute antenna positions
     entered in increasing antenna order.  Only one antenna position
     file is permitted.  The first line of the file is ALWAYS skipped
     and the remaining lines MUST contain three entries corresponding
     to the X, Y, and Z equatorial coordinates, respectively, in units
     of nanoseconds.  The function of this keyword is identical to the
     ``antpos'' keyword except that there is no way to specify a
     subset of antennae; every antenna up to and including the largest
     antenna number must be present in the file.
     NOTE: You may only specify at most one of the ``apfile'',
           ``antpos'', or ``dantpos'' keywords.

Key: antpos
     Inputs are the absolute equatorial coordinates entered in the
     following order (NO checking is done for consistency):
          antpos = A1,X1,Y1,Z1,A2,X2,Y2,Z2,A3,X3,Y3,Z3,....
     The input values are the antenna number and the three equatorial
     coordinates (entered in units of nanoseconds).  Note that A1 does
     not necesarily have to correspond to Antenna 1; it is used to 
     represent the variable containing the antenna number.  Antenna
     (and the corresponding coordinates) not included in the input
     listing do not have their coordinates changed.
     NOTE: An antenna position value of zero is not possible.  If
     an antenna value is set to zero, the current value from the
     data is used.  To force an antenna position value to be zero,
     use the keyword ``dantpos''.
     NOTE: You may only specify at most one of the ``apfile'',
           ``antpos'', or ``dantpos'' keywords.

Key: dantpos
     Inputs are the equatorial coordinate offsets entered in the
     following order (NO checking is done for consistency):
          dantpos = A1,X1,Y1,Z1,A2,X2,Y2,Z2,A3,X3,Y3,Z3,....
     The input values are the antenna number and the three equatorial
     coordinate offsets (entered in units of nanoseconds).  These input
     values are added to the absolute coordinates read from the data.
     Note that A1 does not necesarily have to correspond to Antenna 1;
     it is used to represent the variable containing the antenna
     number.  Antenna present in the data but not included in the
     input value list are treated as having a zero coordinate offset.
     NOTE: You may only specify at most one of the ``apfile'',
           ``antpos'', or ``dantpos'' keywords.

Key: ra
     Input is either an absolute or delta right ascension of the
     phase tracking center.  If one value is present, it is considered
     as a offset position and is to be entered as time seconds.
     Otherwise, three values are expected and are to be entered in
     the following order:
          ra = HH,MM,SS.S
     The right ascension (offset) is relative to the epoch coordinates.
     The default value is 0 seconds offset (no change).

Key: dec
     Input is either an absolute or delta declination of the phase
     tracking center.  If only one value is present, it is considered
     as a offset position and is to be entered in arcseconds.
     Otherwise, three values are expected and are to be entered in
     the following order:
          dec = DD,MM,SS.S
     The declination (offset) is relative to the epoch coordinates.
     The default value is 0 arcseconds offset (no change).  If the
     absolute declination is negative but the DD value is 0, then make
     the MM value negative.  If MM is also 0, then make SS.S negative.

Key: time
     Input is a time offset (in seconds) to be added to the clock time.
     The default value is 0 seconds offset (no change).

Key: delay
     Inputs are the delay error corrections for each antenna.
     The inputs are the delay values for each antenna entered in the
     following order (in units of nanoseconds):
          delay = D1,D2,D3,....
     If no value for delay is specified, the array of antenna values
     are set to 0 nanoseconds offset.  Also, a resulting difference
     (D[i]-D[j]) of less than 0.05 nanoseconds is ignored (no change).
     If a difference exists, the digital wide band data will be
     reconstructed.  All previously flagged narrow band data will
     be ignored in the reconstruction.  Also, the two (2) end
     channels of each window will be ignored in the reconstruction.

Key: out
     The name of the output visibility file.  This parameter is
     ignored when more than one visibility file is given.  If no value
     for ``out'' is given or more than one visibility file is input,
     then the output file name(s) will be the same as the input file
     name(s) but with an "_c" appended to the file name
     (ie. "Vis = saturn,jupiter" will result in output files "saturn_c"
     and "jupiter_c").

Key: options
     Task enrichment options.  Minimum match is active.
       nouv     Do not recompute the u and v variables (coord(1) and
                coord(2), respectively).  This option should, in
                principle, only be used with the delay correction;
                all other corrections should recompute u and v.
       dra
                Multiply the dra values by a cos(obsdec) correction.
                This is used to correct the dra value in the uv
                dataset for MINT data taken at Hat Creek before
                11dec93.  Before that date, the 1/cos(obsdec)
                correction was not applied to the dra in the grid
                file, so that the pointing was incorrect (instead
                of dra arcseconds offsets, the offsets were
                dra*cos(obsdec) arcseconds).
                NOTE:  The obsdec used is the "old" obsdec.  If there
                is a correction in declination, this is NOT applied
                in computing the cos(obsdec).