[evlatests] Dynamic range of images from Widar.

[Sanjay Bhatnagar]

BLCAL solutions as a function of antenna might still show some
correlation.  I.e., baselines involving antenna(s) with significantly
higher leakage might show higher BLCAL solution amplitude.

Sanjay

On Mon, Nov 9, 2009 at 2:39 PM, George Moellenbrock <gmoellen at nrao.edu> wrote:
>
> 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
>>
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