[daip] Re: AIPS - IMAGR question

[Eric Greisen]

Eva Schinnerer writes:
 > 
 > Hi Eric,
 > 
 > when I try to run IMAGR to produce a 8192x8192 image w/ 0.33"/pixels
 > (w/ robust =1) I get the following error message:
 > 
 > aida34> IMAGR1: Task IMAGR  (release of 31DEC04) begins
 > aida34> IMAGR1: Create COSMOS_F16  .IMAGR .   1 (UV)  on disk  1  cno  120
 > aida34> IMAGR1: Beginning channel    1 through    6 with  2 IFs
 > aida34> IMAGR1: IMACPY: Copied  1841068 visibilities to be imaged
 > aida34> IMAGR1: FOR WEIGHTING NEED  2310997 HAVE ONLY  1310720 WORDS IN 'AP'
 > aida34> IMAGR1: PROBLEM AS POSED WILL NOT FIT EVEN IF DATA ARE SORTED
 > aida34> IMAGR1: OUNFWT: ERROR IN UNIFORM WEIGHTING OF UVdata work object
 > aida34> IMAGR1: Purports to die of UNNATURAL causes
 > aida34> IMAGR1: aida34       31DEC04 TST: Cpu=       5.2  Real=      12
 > 
 > The error message presists also when changing the weighting to robust=5, 
 > and also when setting FLDSIZE = 8192 8192 or changing IMSIZE = 6000 6000.
 > IMAGR runs fine when I use an IMSIZE = 4096 4096. I don't think that it is 
 > a memory problem, since I have 4Gb of memory on the machine I use.
 > 
 > The dataset consists of A array 1.4GHz observations w/ multi-channel 
 > continuum mode so I set in IMAGR:

   Two comments - you are doing it wrong and you installed aips wrong.
That sounds harsh so let me amplify:

1. Images of this size at L band with the VLA will be severely
distorted by 3D affects.  Run SETFC with CELLSIZE and IMSIZE set to
zero to see what image size, cell size and filed centers (there will
be rather more than one) it recommends.  With the smaller image sizes,
your current aips installation can do uniform weighting.

2. You should probably change the "AP" size in your installation.  It
is currently only 5 Mbyte.  We use 20 Mbyte here, 80 Mbyte might also
be good for your large memory size.  To do this:

cd $AIPS_ROOT
source LOGIN.CSH          (or , LOGIN.SH for bash)
$CDTST
cd $INC/NOTST/$ARCH
edit PAPC.INC             to select a larger size
COMRPL $APLGEN/ZDCHIN $QPSAP/*.FOR $QOOP/*.FOR
COMLNK $QPGM/*.FOR $QPGNOT/*.FOR $QPGOOP/*.FOR
COMLNK $QYPGM/*.FOR $QYPGNOT/*.FOR
COMLNK $AIPNOT/SETPAR

RUN SETPAR
2
29
99999999            it will complain that this is larger than some
                    limit  - enter that limit
-1
AMANAGER            password
4                   to exit

Eric Greisen

 > 
 > AIPS 1: BCHAN         1                    Low freq. channel 0 for cont.
 > AIPS 1: ECHAN         6                    Highest freq channel
 > AIPS 1: CHANNEL       0                    Restart channel number
 > AIPS 1: NCHAV         6                    Number of chan. to average.
 > AIPS 1: CHINC         6                    Channel incr. between maps.
 > AIPS 1: BIF           1                    First IF in average.
 > AIPS 1: EIF           2                    Last IF in average.
 > 
 > Do you have an idea why this is not working?
 > 
 > Thanks very much,
 >     eva
 > 
 >        ****************************************************
 >                         Dr. Eva Schinnerer
 >              MPIA, Koenigstuhl 17, 69117 Heidelberg, Germany
 >               ph: +49-6221-528-293, fax: +49-6221-528-246
 >                www: http://www.mpia.de/homes/schinner
 >                     email: schinner at mpia.de
 >        ****************************************************