[daip] Question...

[Data Analysts]

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>From l.loinard at astrosmo.unam.mx  Fri Jul 15 16:36:02 2005
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Date: Fri, 15 Jul 2005 17:35:42 -0500
From: Laurent Loinard <l.loinard at astrosmo.unam.mx>
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Hello data analysts,

I have a problem with aips that I hope you might be able
to help me fix..

I just installed aips (version 31DEC04) on a machine here.
Everything worked just fine with the compilation, and I
started to reduce VLBA data with it. Again, everything
seems ok, except for one odd little thing...

I am working with 3.6 cm standard continuum VLBA data
(project BL128EA) and I want to flag the 1st channel of IF4
which looks systematically bad. So I went to uvflg, and
entered

bif 4
eif 4
bchan 1
echan 1
opcode 'flag'
go

Then I ran again possm, and nothing seemed to have
happened. Unsure whether this was because the
flagging had not worked or whether possm just didn't
take it into account, I ran the same uvflg command but
with

bif 0
eif 0

Interestingly, when I ran possm after than, all the first
channels of all the IF had disappeared, EXCEPT for the
1st channel of the 4th IF..

I then spend several hours trying to figure ou what was
wrong, and it looks as though if I want to flag the IF number
i, I need to tell the system I want to flag the IF number (i+1)...
In other words, if I tell aips to flag IF 3, it will flag IF 2 (at least

that's what possm seems to think). Unfortunately for my
immediate purpose, I can't flag IF 4, because for that to
happen, I would need to tell aips to flag IF 5. But then aips
refuses my command because 5 is larger than the total
number of IFs I have..

I am not sure whether it's a bug with aips in general, or with
my version in particular (which would be strange since I
followed the instructions and did not encounter any problem
during the installation). I am not completely sure either if it
has to do with uvflg or with possm...

Any suggestions? (besides jumping out of the window? :-| )

Cheers,
Laurent



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