[daip] UVCON and UVPLT bugs (31DEC06)

[Leonia Kogan]

Michael,

I have tested UVCON using your range of the hour angles -6,6 but using 
time interval aparm(7) =3600. Yes I reproduced the negative elevation 
for SC, although I do not understand the whole picture yet:

I expected to get 540=45*12 visibilities; instead I got 486
Using aparm(6) (elevation)=-90 I got all 540 vis.
So UVCON exclude some visibilities on the basis of EL but...

Anyway I'll look at the problem

Leonia



Michael Bietenholz wrote:

> -- both these based on 31dec06 aips; Timestamp 2006.12.15:05:12:04
> 
> 1:  UVCON's calculation of when the source elevation for seems to be wrong
> in the case of a VLBI array:
> 
> when I run UVCON with, e.g.,
> 
> infi 'AIPSTARS:VLBA_UVCON'
> APARM 8.4095211 0 69.02, -6 6 3 19.6608 32
> BPARM 0;
> 
> ie. supposedly having an elevation cutoff of 3degs, I get a file which
> has data for SC (antenna 10) when the elevation at SC (according to
> UVPLT, REFANT=10; BPARM 11 15 0) is below 0.
> 
> When I changed APARM(6) to 10 degrees, I lost some SC data from the
> end of the simulated run, ie. where the elevation at SC was HIGH
> rather than from the beginning, where it was low, as one might expect.
> 
> Could you confirm this bug for me?  I'm refereeing a paper which
> might have problems because of it.
> 
> 2: (more minor) when UVPLT is plotting the hour angle for a
> visibility, it reasonably tries to plot the average HA for the two
> antennas involved in a particular baseline.  It neglects the fact that
> HA is an angle and HA=-12h is the same thing as HA=+12h.
> 
> This is probably unimportant for the VLA, where, where HA is the same
> for all antennas, but can lead to very confusing results, because
> UVPLT will average HA_1 = +11h and HA_2 =-11.02h to produce HA_avg =
> -0.01h Averaging HA correctly would lead to a value of HA_avg =
> 11.99h.
> 
>    thanks,
> 
>           michael b
> 
> 
> 
> 
> 
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