[evlatests] Back to where we were ...

[Rick Perley]

    New data were taken this morning, with the CBE stated as having 
gotten the phase conjugation right.  I've reviewed the C-band test.

    1) The problems of yesterday (not reported, but in short, phase 
closure was broken, and some other bad characteristics found) are gone.  
We can profitably run the calibration routines. 

    2) The images are still coming out rotated by 180 degrees!  The 
'target' source was observed with the phase tracking center located 1 
arcminute north of the true position.  Thus, when calibrated, we should 
see the source the the south of the phase tracking center, and its 
claimed coordinates should be those in the calibrator manual.  In fact, 
the image shows the source to be north of the map center, with a 
declination two arcminutes to the north of the correct value. 

    Other than this, the data are of excellent quality.  The problem 
with the closures noted two days ago has been  understood (too long a 
story to repeat here, but 'certain individuals', who wish not to be 
named, are moderately embarrassed ... :-) ).  Closure offsets are now 
very small (all less than 0.1% -- at the level expected due to 2nd order 
polarization leakage). 

    I'll send a more detailed report of other things found in the data a 
little later.