[daip] RE: FRPLT and POSSM with SHIFT

[Leonia Kogan]

Slava,

You wrote:

>The new FRPLT provides an
>option of the search for position shift. This is a very useful option which
>can be used for determination of absolute coordinates as an alternative to
>SAD. 

FRPLT does not provide a 'search shift'. It recalculates the UV data 
to the new position of the tangent point. 

As I understand, you use FRPLT 
to determine the position of the source component looking at the change of 
the fringe rate.

AIPS has a special task for this purpose: FRMAP.
This task create the map of the source based on the fringe rate change.
The task works especially for spectral line sources where it create the image 
relatively the selected  frequency channel. It can be used to make more 
exact the absolute coordinate also. The last option is used for continum 
source when its position has not known apriori with enough accuracy.

>However my first attempt with the 'search shift' option
>was not successfull: it did not produce any output.

What does it mean? It does not produce any plot with the non zero shift 
and make the plot with shift=0?
Does FRPLT succesfully finish with nonzero shift or not?

I am not sure that you have the corrected version at your computer.
I put it in both 'tst'=31DEC01 and 'new'=31DEC00, but I do not know 
if MNJ serves your machine to make the changes. WE'll investigate it here.
Or the changes has not come to you yet. Try it again later.

You can check the fortran codes:
The corrected version has:

                  FRSCL = 1.0D0 + (FOFF(LOOPIF) + FINC(LOOPIF) *
     *               (LOOPF + 1 - PBCHAN - CATR(KRCRP+JLOCF))) / UVFREQ
The old version had:

                  FRSCL = 1.0D0 + (FOFF(LOOPIF) + FINC(LOOPIF) *
     *               *(LOOPF - CATR(KRCRP+JLOCF))) / UVFREQ

The corrected version of FRPLT works at my machine here.

Leonia