[evlatests] VLBI at the EVLA test report

[Gregory Taylor]

Hi Ken,

     Regarding the phasing of the VLA antennas I attach two plots, one
that shows the phasing with integration number for several scans
for an EVLA antenna (13) and a VLA antenna (5).  Both are close
to the reference antenna (24).  Clearly antenna 5 is changing but
not converging.  I also attach an excerpt from the CALIB phase
solutions which also shows from the phase solutions on the nearby
calibrator J0310+38 are well offset from zero.  Looks to me like the
correction being made to the VLA antennas is almost random.
Ciao,
                                            - Greg

   Time   Source     -- 1-- 2-- 3-- 4-- 5-- 6-- 7-- 8-- 9--10
19:15:30 3C84        -38  26 -56-138   2 -23 134 -87  60 -84
19:15:45 3C84        -48 -64  58 124  38 -15 -68 -80  99 -66
19:16:05 3C84          7 -93  24 155  60  27 -99 -35 115 -32
19:16:25 3C84         25 -41 -70 134  43  30  25 -30  91 -45
19:16:40 3C84          0 -28 -58 121  31   4  38 -53  82 -66

19:17:20 J0310+38    -60-118 132-156  75  -1 126 -75 109 -61
19:17:30 J0310+38    -60-121 126-156  75  -2 123 -77 111 -63
19:17:45 J0310+38    -61-121 123-156  80  -2 119 -80 111 -65
19:18:05 J0310+38    -62-125 119-155  87  -6 114 -84 108 -64
19:18:25 J0310+38    -65-131 113-157  88  -9 111 -88 100 -68
19:18:40 J0310+38    -65-131 107-155  92 -11 109 -87  99 -71

19:19:20 3C84         46   1 177 -50  23  21-166 -25  76 -52
19:19:30 3C84         78   4-132 168 148  92-120-147-180-147
19:19:45 3C84         -6 -75 156-166 119  31  22-110 136 -95
19:20:05 3C84        -48 -98-121 156  32 -26  28 -24-162 -22
19:20:25 3C84          2 -49-144-139  35  -2 -71 -24 155 -34
19:20:40 3C84         21 -39  -7-124  80  23 -81 -67 132 -72

19:21:20 J0310+38    -38-123  66 123 133  17 148 -81-107 -68
19:21:30 J0310+38    -36-118  59 126 137  19 147 -78-103 -65
19:21:45 J0310+38    -38-123  53 127 140  22 146 -77-104 -67
19:22:05 J0310+38    -39-127  46 127 143  20 138 -81-107 -70
19:22:25 J0310+38    -37-125  42 129 149  20 132 -76-106 -68
19:22:40 J0310+38    -35-124  41 130 151  23 128 -76-112 -65

-------------- next part --------------
A non-text attachment was scrubbed...
Name: stack13.ps
Type: application/postscript
Size: 6693 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20070621/605e9782/attachment.ps>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: stack5.ps
Type: application/postscript
Size: 6718 bytes
Desc: not available
URL: <http://listmgr.nrao.edu/pipermail/evlatests/attachments/20070621/605e9782/attachment-0001.ps>
-------------- next part --------------

On Jun 20, 2007, at 8:21 PM, Ken Sowinski wrote:

> The surprising failure reported here is that the VLA antennas failed
> to phase; I expected this to work.  A diagnostic would be to look
> at the time behavior of the phases.  If they are wrong and constant
> then we are not trying at all to correct the phase or antsol is not
> providing gain solutions for those antennas.  If they are wrong and
> changing then we are applying the phase correction improperly, either
> wrongly scaled or with the wrong sign.
>
> The reference antenna choice is interesting because we are used to
> allowing the operator control over this with the ability to change
> reference antenna as whim or necessity dictate.  Embedding the
> choice in the script makes the it static unless we allow someone
> to edit the script and restart it.  Maybe a something like  
> subarray.setRefant() needs to be made available to the operator.
> I have suggested the need for a "front panel" interface for the
> VLA before and this is an example of a use for it.
>
> Once the problems Walter noted with Y1 are addressed we should find
> time for another go at testing it, even without phased array support.
>
>