[evlatests] Dynamic range of images from Widar.

[George Moellenbrock]

Thanks, Steve, I was going to chime in with pretty much the same point. 
One additional point (related to points made in longer emails last week):

The gain calibration will soak up some portion of the (1+D*D) effect, and 
probably in such a way as to destroy any correlation that might occur if 
the degenerate referencing Steve describes didn't already obscure it 
(e.g., if arbitrarily setting one of the RCP Ds to zero happened to be not 
too far off the truth).  So, the Ds you get from the cross-hand data are 
in an arbitrary frame _AND_ the D-induced post-gain calibration BLCAL 
solutions have been shifted, thereby likely scrambling any correlation
we might expect here.

-George


On Mon, 9 Nov 2009, Steven T. Myers wrote:

>
> On Mon, 9 Nov 2009, Vivek Dhawan wrote:
>
>> 2. Whence the non-closing errors?
>>
>> If BL errors originate in polarization leakage, then the correction
>> for a baseline should correlate with the magnitude of polarization
>> leakage (D-term) on that baseline.
>>
>> Plots:
>> 1. BL correction (re & im) vs. pol leakage - only weak correlation.
>
> I fear we should not read too much into this.  As George has pointed out
> that the leakages in the 1+D_iRD_jR* term (for RR) are not the same leakages as
> come out of the PCAL/polcal cross-hand leakages which come from solving for
> (D_iR + D_jL*) like terms, which have a degeneracy for example where an offset
> d_RL can be added to each D_iR and its conjugate subtracted from D_jL without
> changing the solution.  In this model, the RR_ij is corrupted by
> [1 + (D_iR+D_RL)(D_jR*+D_RL*)]
>    = [1 + D_iRD_jR* + D_iRD_RL* + D_jR*D_RL + D_RL^2]
> of which the non-closing part is the ratio of this to its antenna-based average.
> George can elaborate if I'm too far off-base.
>
>   -s
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.cv.nrao.edu
> http://listmgr.cv.nrao.edu/mailman/listinfo/evlatests
>

--