[evlatests] [Fwd: UVW reversed on 74 MHz data set]

[Ken Sowinski]

On Mon, 10 Sep 2007, Rick Perley wrote:

>    All:
>
>    Aaron Cohen reports his images from 74 Mhz data taken last week are
> reversed along both axes.
>
>    I thought this one had been fixed up.  Is there something else going
> on?

Aaron reports that he uvfix did not help so it is not a uvw
problem unless he grossly misused uvfix.

Has anyone made a map at 300 MHz?  To narrow the possibilities
it might be enlightening to make VLA-only and EVLA-only maps.

Ken



> -------- Original Message --------
> Subject: 	UVW reversed on 74 MHz data set
> Date: 	Mon, 10 Sep 2007 14:42:04 -0400
> From: 	Aaron Cohen <cohen at charleston.nrl.navy.mil>
> Reply-To: 	aaron.cohen at nrl.navy.mil
> To: 	Rick Perley <rperley at aoc.nrao.edu>
> CC: 	aaron.cohen at nrl.navy.mil
>
>
>
> Hi Rick,
>
> I've been trying to reduce a 74 MHz observation from Sept. 1.  After
> failing to get any sensible calibration solutions I just made a raw
> image of the center facet and found all source positions flipped in both
> east-west and north south axes.  They are also heavily smeared toward
> the edges (more than bw smearing could have done) indicating that the w-
> terms might be reversed also.
>
> I've heard that there were some problems with the UVW's being reversed
> in some of the data recently and that this could be fixed with UVFIX.
> But I tried this and it didn't help.  Any ideas?  Have you noticed this
> problem at 74 MHz?
>
> cheers,
> Aaron
>
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