[daip] Re: What am I doing wrong?

[Eric Greisen]

Patrick Palmer writes:

 > I have been working on some old data from the archive.  (1983) I was
 > taken in the bad old days of limited data recording, so it has only one
 > IF.
 > 
 > In the part of the data of interest, there is no primary calibrator.  I
 > used the other part of the data to determine the flux of the secondary
 > calibrator, and used SETJY to insert this flux in the SU table.  I
 > entered it as an I flux with the other stokes values = 0.  PRTAB shows
 > it is fine.

    Run LISTR with OPTYPE='SCAN' so I can see (and PRTAB) and send the
output

 > 
 > But, when running CALIB it acts like there is no flux for the secondary
 > calibrator and uses 1 Jy, so when I use GETJY to determine the flux of
 > another secondary calibrator, the value comes out in the correct ratio
 > between the two, but ignores the zerosp flux, so it is relative to
 > 1Jy.
 > 
 > Beyond whatever error I have above, FILLM does not produce correct
 > headers for this data.  I thought I should let you know because I had
 > known about the BW code 9 problem for years, but just fixed it myself
 > and ddin't say anything.
 > 
 > In particular, the coord. increment on the frequency axis is
 > incorrect.  The following header is for line data.  It is 128 channel
 > data, but 1.56 MHz BW, not 50 MHz.  (I haven't figured out if the
 > reference pixel is correct yet.)  For channel 0 it says the bandwidth
 > is 4.7500001E+09. 

       Were these data in BW code 9?  I wonder what the data are
telling FILLM - something wierd clearly.  I suspect it goes back to
what was recorded in 1983 and then translated when the formats were
updated.

Eric Greisen


 > 
 > AIPS 1: Image=MULTI     (UV)         Filename=DEC83_H2CO  .LINE  .   2
 > AIPS 1: Telescope=VLA                Receiver=VLA
 > AIPS 1: Observer=AG127               User #=  347
 > AIPS 1: Observ. date=16-DEC-1983     Map date=15-FEB-2006
 > AIPS 1: # visibilities     12234     Sort order  TB
 > AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  BASELINE  TIME1
 > AIPS 1:            SOURCE  FREQSEL  WEIGHT  SCALE
 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
 > AIPS 1: COMPLEX      1   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: FREQ       127   4.8287946E+09       0.00  5.0000000E+07    0.00
 > AIPS 1: STOKES       1  -1.0000000E+00       1.00 -1.0000000E+00    0.00
 > AIPS 1: IF           1   1.0000000E+00       1.00  1.0000000E+00    0.00
 > AIPS 1: RA           1    00 00 00.000       1.00       3600.000    0.00
 > AIPS 1: DEC          1    00 00 00.000       1.00       3600.000    0.00
 > AIPS 1: ----------------------------------------------------------------
 > AIPS 1: Coordinate equinox 1950.00
 > 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 NX is   1
 > AIPS 1: Maximum version number of extension files of type SU is   1
 > AIPS 1: Maximum version number of extension files of type FQ is   1
 > AIPS 1: Maximum version number of extension files of type CL is   1
 > AIPS 1: Maximum version number of extension files of type TY is   1
 > AIPS 1: Maximum version number of extension files of type WX is   1
 > AIPS 1: Keyword = 'OBSCHANS'  value =          128
 > AIPS 1: Keyword = 'CORRMODE'  value = '2A      '
 > AIPS 1: Keyword = 'SELCHANS'  value =          127
 > AIPS 1: Keyword = 'VLAIFS  '  value = 'A       '
 > 
 > (Of course in that era, the error may be in what was written by the
 > online system.)
 > 
 > Pat