[daip] Frequency coordinates(31DEC05 vs 31DEC04)

[Neeraj Gupta]

Dear Eric,

        Greetings from NCRA, Pune.  We have recently upgraded general user 
machines at the GMRT site to frozen AIPS' version 31DEC05.  We have 
noticed that some of the AIPS tasks (like IMAGR) are goofing up in reading 
the correct sign of frequency increment from our FITS files.  These FITS 
files were generated using native programmes LISTSCAN and GVFITS on GMRT 
datasets.  The above problem is there only for 31DEC05 and with 31DEC04 
things are/have been fine.  Could you please tell us what has been changed 
between '04 and '05 versions to cause this problem?  I have appended to 
this mail an illustration of the problem.  It may be noticed that 31DEC04 
ISPEC and IMAGR frequency values (and the increment) are consistent with 
those of ISPEC output of 31DEC05.  However, the same is not true for 
31DEC05's IMAGR.


regards,
neeraj


########IMHEADER output of the data (Same for 31DEC04 and 05)
---------------------------------------
FITLD1:            SOURCE  FREQSEL  WEIGHT  SCALE
FITLD1: ----------------------------------------------------------------
FITLD1: Type    Pixels   Coord value     at Pixel     Coord incr   Rotat
FITLD1: COMPLEX      1   1.0000000E+00       1.00  1.0000000E+00    0.00
FITLD1: STOKES       1  -1.0000000E+00       1.00 -1.0000000E+00    0.00
FITLD1: FREQ       128   6.1400000E+08       0.50 -1.2500000E+05    0.00
FITLD1: IF           1   1.0000000E+00       1.00  1.0000000E+00    0.00
FITLD1: RA           1    00 00 00.000       1.00       3600.000    0.00
FITLD1: DEC          1    00 00 00.000       1.00       3600.000    0.00
FITLD1: ----------------------------------------------------------------



####FQ table read through PRTAB (Same for both the versions)
-------------------------------------------------------------------
COL. NO.         1              2               3              4 
5
      ROW      FRQSEL      IF FREQ           CH WIDTH       TOTAL BAN 
SIDE BAND
   NUMBER                  Hz                Hz             Hz
        1         1        0.000000E+00      1.250E+05      1.600E+07 
-1


######IMAGR and ISPEC output for 31DEC04 (Only few of the relevant lines)
--------------------------------------------------------
IMAGR1: Task IMAGR  (release of 31DEC04) begins
IMAGR1: Beginning channel    1 through    1 with  1 IFs
IMAGR1: GRDMEM: Frequency 6.139375E+08 Hz
IMAGR1: Beginning channel    2 through    2 with  1 IFs
IMAGR1: GRDMEM: Frequency 6.138125E+08 Hz
IMAGR1: Beginning channel    3 through    3 with  1 IFs
IMAGR1: GRDMEM: Frequency 6.136875E+08 Hz
IMAGR1: Appears to have ended successfully

ISPEC1: BDROP AND EDROP IGNORED: OUT OF RANGE
  godot     ISPEC(31DEC04)     10     09-FEB-2006  18:19:20    Page    1
3C286  RA 13 31 08.242  DEC 30 30 31.54  MULTI.IBM001.2
pixel    coord.value       avg over area
     1    6.13937500E+08    8.7237996E-01
     2    6.13812500E+08    8.7263072E-01
     3    6.13687500E+08    8.7272072E-01
ISPEC1: GFINIS: number records used       4
ISPEC1: Appears to have ended successfully
ISPEC1: godot        31DEC04 TST: Cpu=       0.0  Real=       0
AIPS 1: Resumes


#######IMAGR and ISPEC output for 31DEC05
-----------------------------------------------------
IMAGR2: Task IMAGR  (release of 31DEC05) begins
IMAGR2: Beginning channel    1 through    1 with  1 IFs
IMAGR2: GRDMEM: Frequency 6.140625E+08 Hz
IMAGR2: Beginning channel    2 through    2 with  1 IFs
IMAGR2: GRDMEM: Frequency 6.141875E+08 Hz
IMAGR2: Beginning channel    3 through    3 with  1 IFs
IMAGR2: GRDMEM: Frequency 6.143125E+08 Hz
IMAGR2: Appears to have ended successfully

ISPEC:
  yayati    ISPEC(31DEC05)    100     09-FEB-2006  18:15:58    Page    1
3C286  RA 13 31 08.242  DEC 30 30 31.54  MULTI.IBM001.1
pixel    coord.value       avg over area
     1    6.13937500E+08    8.7228334E-01
     2    6.13812500E+08    8.7215716E-01
     3    6.13687500E+08    8.7194872E-01
     4    6.13562500E+08    8.7185401E-01
     5    6.13437500E+08    8.7176234E-01






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Neeraj Gupta                       Phone : 91-20-25697107,25691384
NCRA (TIFR),                               office extn. 253
University of Pune Campus, 
Ganeshkhind,                       email : neeraj at ncra.tifr.res.in 
Pune - 411 007
India