[daip] FRING queustion

[Andrzej Marecki]

Dear Eric et al.

It's perhaps elementary and - what's most important - it works for me.
Still, I need an expert's opinion w.r.t. this matter to be used in the
discussion with the referee of my paper.

OK, so let's go to the point. 

My VLBA observation was carried out with phase calibration sources included.
During the processing I run FRING on phase-cals and then I apply the delay &
rate solutions to my target sources. The absolute positions of the targets
are therefore well defined. So far so good: it's obvious and elementary.

Now, imagine that for some (strong) targets I re-run FRING on a target (one
FRING run per source, of course) and I specify (using IN2NAME, IN2CLASS,
IN2SEQ) a clean map of that target resulting from previous stage of -
phase-referenced! - processing as a model. Needless to add, I specify
CALSOUR, too. So, what do I get this time? Again a map with correct absolute
positions! This is what I simply find: the map made with bona fide
phase-referencing and the map made from the u-v data coming out from FRING
*with* phase-referenced map used as a model have the same coordinates.

In my opinion this is what I should get and such a behavior is normal. (The 
referee does not believe it.)

Finally, imagine a more complicated situation. I have another VLBI observation
of a given target made at a _different_ frequency. That observation was
carried out *without* phase-cals. OK, so what I do is I run FRING on that
data with... a phase-referenced map obtained from the experiment I mentioned
above used as model. It looks that the absolute position has been transferred
this way to a non-phase-referenced observations. Again, my referee does not
believe it and claims I have lost the absolute positions in my
non-phase-referenced experiment. If that's the truth, then why-oh-why the
coordinates of the non-phase-referenced maps luckily fit the ones of the
phase-referenced maps used as a model in FRING???

Thanks in advance for helping me with my argument with the referee.

Best regards and wishes,

Andrzej

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Andrzej Marecki                | 
Torun Centre for Astronomy     |   e-mail: amr at astro.uni.torun.pl
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