[daip] concatenate two uv databases

[Eric Greisen]

Christian Leipski writes:
 > Hello Eric!
 > 
 > The problem appears not only with the files of one source but with all
 > files (3 sources) at this frequency. We observed 6 sources, three at 4.8
 > GHz and three at 8.5 Ghz. I got the data in two different files (one for
 > each frequency). There is no problem with the 4.8 GHz data. Only the 8.4
 > GHz data are strange. I had trouble with them right from the beginning of
 > the flagging. The visibilities of the scan first rises and then starts
 > from zero again after one third of the observations.
 > I have contacted you because of this problem two or three weeks ago and
 > you suggested do delete the NX files, resort the data and then create the
 > NX again. This worked fine and the flagging and calibration after that
 > too. Mapping of this data alone are without any problems.
 > 
 > > Could you send me the IMHEADER for each of the two input files?
 > 
 > O.K.:
 > 
 > A-Array:
 > 
 > AIPS 1: Image=PG0026+1  (UV)         Filename=PG26UV      .SPLIT .   1
 > AIPS 1: Telescope=VLA                Receiver=VLA
 > AIPS 1: Observer=AF361               User #= 2173
 > AIPS 1: Observ. date=24-JUL-1999     Map date=26-FEB-2003
 > AIPS 1: # visibilities    259209     Sort order  TB
 > AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  BASELINE  TIME1
 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
 > AIPS 1: COMPLEX      3   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: STOKES       4  -1.0000000E+00       1.00 -1.0000000E+00    0.00
 > AIPS 1: FREQ         1   8.4351000E+09       1.00  5.0000000E+07    0.00
 > AIPS 1: IF           2   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: RA           1    00 29 13.701       1.00       3600.000    0.00
 > AIPS 1: DEC          1    13 16 04.270       1.00       3600.000   -0.03

     This has had the epoch switched from 1950 to 2000 and hence has a
small rotation wrt to the other.  Do

KEYWORD='CROTA6'; GETH; ROTATE = -KEYV(1); SORT='TB'; go uvsrt

This will rotate the u and v of this data set to be aligned with
north-south in J2000.  Then DBCON can work.

Eric Greisen

 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Coordinate equinox 2000.00
 > AIPS 1: Rest freq      0.000         Vel type: OPTICAL wrt YOU
 > AIPS 1: Alt ref. value  0.00000E+00  wrt pixel    1.00
 > AIPS 1: Maximum version number of extension files of type FQ is   1
 > AIPS 1: Maximum version number of extension files of type HI is   1
 > AIPS 1: Maximum version number of extension files of type WX is   1
 > AIPS 1: Maximum version number of extension files of type AN is   1
 > AIPS 1: Maximum version number of extension files of type SN is  38
 > 
 > 
 > B-Array:
 > 
 > AIPS 1: Image=PG0026+1  (UV)         Filename=PG0026-B    .SPLIT .   1
 > AIPS 1: Telescope=VLA                Receiver=VLA
 > AIPS 1: Observer=AL603               User #= 2173
 > AIPS 1: Observ. date=27-DEC-2003     Map date=06-FEB-2004
 > AIPS 1: # visibilities    247573     Sort order  TB
 > AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  BASELINE  TIME1
 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
 > AIPS 1: COMPLEX      3   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: STOKES       4  -1.0000000E+00       1.00 -1.0000000E+00    0.00
 > AIPS 1: FREQ         1   8.4351000E+09       1.00  5.0000000E+07    0.00
 > AIPS 1: IF           2   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: RA           1    00 29 13.700       1.00       3600.000    0.00
 > AIPS 1: DEC          1    13 16 04.000       1.00       3600.000    0.00
 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Coordinate equinox 2000.00
 > AIPS 1: Rest freq      0.000         Vel type: OPTICAL wrt YOU
 > AIPS 1: Alt ref. value  0.00000E+00  wrt pixel    1.00
 > AIPS 1: Maximum version number of extension files of type FQ is   1
 > AIPS 1: Maximum version number of extension files of type HI is   1
 > AIPS 1: Maximum version number of extension files of type AN is   1
 > AIPS 1: Maximum version number of extension files of type WX is   1
 > AIPS 1: Maximum version number of extension files of type OF is   1
 > 
 > 
 > 
 > 
 >