[daip] [Mnj] UVFLG, FITLD patches - New helpdesk

[Eric Greisen]

Luca Moscadelli wrote:
> Dear Eric,
> 
> Running 31DEC10 task SPLAT, I found (maybe) a bug. The splitted file has 
> the
> wrong "velocity reference" pixel.
> 
> The input is a multisource file with 1024 channels. The source "I20126" 
> has velocity defined in the SU table:
> 
> _OW   ID. NO.   SOURCE       QUAL   CALCODE   IFLUX       QFLUX       UFLUX
>   NUMBER                                           JY          
> JY          JY
>        1      1      I20126         1              0.000E+00   
> 0.000E+00   0.000E+00
> 
> 
> 
> COL. NO.        13              14             15             
> 16             17
>      ROW   EPOCH          RAAPP           DECAPP         LSRVEL         
> RESTFREQ
>   NUMBER   YEARS          DEGREES         DEGREES        M/SEC          HZ
>        1   2.000000E+03   -5.631436E+01   4.124937E+01   3.885269E+04   
> 6.668519E+09
> 
> 
> with channel 1 corresponding to 3.885269E+04 M/SEC
> 
> I have "splatted" the channel range 480 - 550.
> The header of the splatted file is:
> 
> 
> AIPS 1: Image=I20126    (UV)         Filename=I20126      .SP_ALL.   1
> AIPS 1: Telescope=EVN                Receiver=VLBA
> AIPS 1: Observer=EM064D              User #=    2
> AIPS 1: Observ. date=11-MAR-2009     Map date=15-MAR-2010
> AIPS 1: # visibilities    166753     Sort order  TB
> AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  TIME1  BASELINE
> AIPS 1:            INTTIM  CORR-ID  WEIGHT  SCALE
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
> AIPS 1: COMPLEX      1   0.0000000E+00       1.00  1.0000000E+00    0.00
> AIPS 1: STOKES       2  -1.0000000E+00       1.00 -1.0000000E+00    0.00
> AIPS 1: FREQ        71   6.6682020E+09    -478.00  1.9531250E+03    0.00
> AIPS 1: IF           1   1.0000000E+00       1.00  1.0000000E+00    0.00
> AIPS 1: RA           1    20 14 26.050       1.00       3600.000    0.00
> AIPS 1: DEC          1    41 13 32.700       1.00       3600.000    0.00
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: Coordinate equinox 2000.00
> AIPS 1: Rest freq   6668.519         Vel type: RADIO   wrt LSR
> AIPS 1: Alt ref. value  3.88527E+04  wrt pixel -957.00
> AIPS 1: Maximum version number of extension files of type NX 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 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 SN is   1
>>
> 
> The reference velocity is correct but the reference pixel is -957, 
> instead of -478.
> 
> 
> USing the DEC06 SPLAT, instead the result appears correct.
> The header of the splatted file is:
> 
> 
> AIPS 1: Image=I20126    (UV)         Filename=I20126      .SP_ALL.   3
> AIPS 1: Telescope=EVN                Receiver=VLBA
> AIPS 1: Observer=EM064D              User #=    2
> AIPS 1: Observ. date=11-MAR-2009     Map date=17-MAR-2010
> AIPS 1: # visibilities    166753     Sort order  TB
> AIPS 1: Rand axes: UU-L-SIN  VV-L-SIN  WW-L-SIN  TIME1  BASELINE
> AIPS 1:            INTTIM  CORR-ID  WEIGHT  SCALE
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
> AIPS 1: COMPLEX      1   0.0000000E+00       1.00  1.0000000E+00    0.00
> AIPS 1: STOKES       2  -1.0000000E+00       1.00 -1.0000000E+00    0.00
> AIPS 1: FREQ        71   6.6682020E+09    -478.00  1.9531250E+03    0.00
> AIPS 1: IF           1   1.0000000E+00       1.00  1.0000000E+00    0.00
> AIPS 1: RA           1    20 14 26.050       1.00       3600.000    0.00
> AIPS 1: DEC          1    41 13 32.700       1.00       3600.000    0.00
> AIPS 1: ----------------------------------------------------------------
> AIPS 1: Coordinate equinox 2000.00
> AIPS 1: Rest freq   6668.519         Vel type: RADIO   wrt LSR
> AIPS 1: Alt ref. value  3.88527E+04  wrt pixel -478.00
> 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
> 
> with reference pixel -478.
> 
> It seems that DEC10 SPLAT calculates ref pixel wrong by a factor of 2.

Yo0u are absolutely correct and I have fixed 31DEC10 (available via MNJ 
tomorrow) and 31DEC09 (available via MNJ or patch now).

Eric Greisen