[evlatests] P-band dipole orientations

[Claire Chandler]

Hi Rick,

It is interesting that you are finding that the ionospheric corrections 
are over-correcting the data. We noticed the same thing when we were 
investigating the TEC corrections for VLASS a while ago using the data 
from Goddard, and a comparison with higher time-resolution data from JPL 
indicates that the Goddard TECs are probably too high. This might be the 
source of the over-correction. Frank probably has more details.

Claire

On 3/17/23 10:59 AM, Rick Perley via evlatests wrote:
> In order to check the many changes Eric has implemented in AIPS to 
> better handle linearly polarized antennas, I requested, and was given, 
> an 8-hour observation of the Moon, at P-band, last December.
>
> The resulting images are very good.  The changes Eric has implemented 
> now permit application of ionospheric Faraday rotations -- these do 
> indeed correct (actually, slightly overcorrect) the ionospheric RM 
> rotation.
>
> The calibration of the data also provide us the dipole position angle 
> deviations w.r.t. the reference antenna dipole.  For this work, I used 
> ea24.  Following is a table of dipole misorientations (all w.r.t. 
> ea24).  Accuracy is about 0.5 degrees.
>
> Antenna     Rotation angle (deg)
>
> ------------------------------------------
>
> ea01        +3
>
> ea02    -1
>
> ea03    +6
>
> ea04     +6
>
> ea05    -1
>
> ea06    +1
>
> ea07    -4
>
> ea09    +2
>
> ea10    -3
>
> ea11    -5
>
> ea13    -1
>
> ea14    -6
>
> ea15    +1
>
> ea16    -2.5
>
> ea17    -3
>
> ea18    +1.5
>
> ea19    +3
>
> ea20    +3
>
> ea21    -2.5
>
> ea22    +4.5
>
> ea23    -1
>
> ea25    -6 -- there is strong coupling, not due to rotation, between 
> the Vertical and Horizontal channel data.
>
> ea26    +2
>
> ea27    -6
>
> ea28    +1
>
> ------------------------------------------------------------
>
> For all antennas other than ea25, the 'leakage' coupling between 
> channels ('D' terms) is completely dominated by the dipole rotation.  
> Only ea25 shows a significant coupling from other sources -- 
> presumably electronic.
>
> _______________________________________________
> evlatests mailing list
> evlatests at listmgr.nrao.edu
> https://listmgr.nrao.edu/mailman/listinfo/evlatests