[daip] JMFIT

[Lynn D. Matthews]

I am attempting to use JMFIT to fit a simple elliptical Gaussian and
wish to hold the position angle fixed. To do this I am entering values
for GWIDTH=bmaj,bmin,pa and setting DOWIDTH 1,1,-1. I attach my full
inputs below.

The program reports in the messages that the PA is being held fixed to my
requested value. However, if the PA I enter is is in the range 58deg< PA
\le 90deg, the PA reported for the fit is always PA+90. if PA>90, it
reports PA-90. An error on PA is also reported despite the fact that
"print dowidth" after the fit reveals an uncertainty of zero for the PA
(and the correct errors for BMIN and BMAJ).  These behaviors do not occur
if I also fix bmaj and bmin during the fit; in this case it reports my
requested PA with error +/- 0.

Lynn Matthews

AIPS 1: JMFIT: Task to fit Gaussian models to an image by least-squares
AIPS 1: Adverbs     Values                 Comments
AIPS 1: ----------------------------------------------------------------
AIPS 1: USERID        0                    User ID. 0 => current user,
AIPS 1:                                      32000 => any user.
AIPS 1: INNAME     'RSCNC R1BX'            Input image name (name)
AIPS 1: INCLASS    'MOM0'                  Input image name (class)
AIPS 1: INSEQ         2                    Input image name (seq. #)
AIPS 1: INDISK        3                    Input image disk drive #
AIPS 1: BLC         245         249        Bottom Left corner of fit
AIPS 1:               1           1           1           1
AIPS 1:               1
AIPS 1: TRC         258         263        Top Right corner of fit
AIPS 1:               1           1           1           1
AIPS 1:               1
AIPS 1: OUTNAME    'TST'                   Output image name (name)
AIPS 1: OUTCLASS   '0'                     Output image name (class)
AIPS 1: OUTSEQ        0                    Output image name (seq. #)
AIPS 1: OUTDISK       3                    Output image disk drive #
AIPS 1: NGAUSS        1                    Number of components
AIPS 1: CTYPE      *all 0                  Model types; one for each
AIPS 1:                                     component
AIPS 1:                                     0->1=Gaussian
AIPS 1:                                     2=Zero level; 3=Zero+slope
AIPS 1:                                     4=Zero+slope+curve;
AIPS 1:                                     5=see HELP JMFIT
AIPS 1:                                    Guess of model parameters
AIPS 1: GMAX        111         111        Peak of component (JY)
AIPS 1:             111         111          0-> Use maximum value
AIPS 1: GPOS        252.026     254.537    (X,Y) position (pixels)
AIPS 1:            *rest 0                   0-> Use position of max
AIPS 1: GWIDTH       11          10        (BMAJ, BMIN, PA) of comp.
AIPS 1:              10        *rest 0       (pixels,pixels,deg)
AIPS 1:                                      0->Use clean beam
AIPS 1: DOMAX         2.5179      1        Solve for GMAX?  >0 -> yes
AIPS 1:               1           1          returns the error
AIPS 1: DOPOS         0.1842      0.2453   Solve for GPOS?  >0 -> yes
AIPS 1:            *rest 0                   returns the error
AIPS 1: DOWIDTH       1           1        Solve for GWIDTH? >0-> yes
AIPS 1:              -1        *rest 0       returns the error
AIPS 1: BWSMEAR       0                    Bandwidth smearing corr.
AIPS 1: RADIUS        0                    Radius for finding RMS
AIPS 1: NITER      4000                    Maximum # of iterations
AIPS 1:                                      0->20*NGAUSS
AIPS 1:                                    Solve for model parameters?
AIPS 1: DOCRT        80                    <=0 -> Print maps and
AIPS 1:                                      solutions on line printer
AIPS 1: OUTPRINT   ' '
AIPS 1:                                    Printer disk file to save
AIPS 1: DOOUTPUT      1                    >0 -> 1 Catalog residual map
AIPS 1: OFFSET        0                    Cutoff level. 0-> None
AIPS 1: DOMODEL      -1                    > 0 => put solutions in a CC
AIPS 1:                                    file with input image
AIPS 1: OUTVERS       0                    MF table version number
AIPS 1:                                       -1 => none, 0 => new
AIPS 1: PRTLEV        2                    Level of messages desired:
AIPS 1:                                      0 normal, 1 some extra,
AIPS 1:                                      2 iteration results
AIPS 1: PBPARM     *all 0                  Primary beam parameters:
AIPS 1:                                    (1) level to believe - <= 0
AIPS 1:                                    means do not apply a primary
AIPS 1:                                    beam (2) > 0 use (3)-(7)