[evlatests] WIDAR Map rotation

[Rick Perley]

    I reported some time ago that images made with WIDAR data showed the 
sky rotated by 180 degrees from the correct orientation.   This means 
the data being gridded are the complex conjugate of the correct values 
(phases are negated), since the baselines are known to be correctly 
described. 

    The above were determined from L and C band observations.  It turns 
out that this map rotation characteristic is *not* true at X-band -- 
data taken of 3C273 last night are correctly oriented. 

    X-band is unique in that it is of opposite sideband from the other 
bands -- so the frequency ordering coming out of the correlator are 
reversed.