[evlatests] Something to worry about?

[Ken Kellermann]

Interesting!

Does it show up in the dirty image?

Does it show up in the CLEAN image before self cal?

> -----Original Message-----
> From: evlatests-bounces at nrao.edu [mailto:evlatests-bounces at nrao.edu] On
> Behalf Of Rick Perley
> Sent: Friday, December 02, 2011 6:37 PM
> To: evlatests at aoc.nrao.edu
> Subject: [evlatests] Something to worry about?
> 
>       I attach something which I hope is a curiosity, but may portend
> something more worrisome ...
> 
>     The northern-stability test was done on the source known as
> J0019+7327.  Unbeknown to me, this object has a quite strong nearby
> neighbor.  At 1441 MHz, the neighbor is about 1/4 the brightness of the
> target source, and is located 20 arcminutes to the SE.  After
> correction of the primary beam, its peak brightness is about 620
> mJy/beam, while the target source is 550 mJy/beam.
> 
>     The image is quite nice, but look at the position diametrically
> opposite the bright neighbor -- there is a clear 'anti-source', which
> is
> *exactly* located on the reflected position of the bright neighbor.
> The usual self-calibration (where the anti-source is excluded from the
> model) is unsuccessful in removing the 'hole'.   The hole depth is only
> a few mJy, so the effect is small.  But is it real?  And if so, what
> did it?
> 
>     I attach a .png file for viewing.