[evlatests] Baselines; Focus vs. elevation.

[Vivek Dhawan]

I now have solutions for EVLA antenna positions.

They work, i.e., when applied, the phase residuals drop from
100's of degrees to 10 or 20 deg, and are consistent from day
to day. The offsets are a bit higher than is usual for VLA
antennas, which makes me suspect that the phase variation from
the electronics is inflating the fitted offsets. However, it
is certainly better to apply them than not.

Corrections applicable to data from 2007 March 12 onward are
in the first table, in CLCOR-ready format, offsets in m.
This table is for focus vs. elevation ON (corrected online).

Though not the dominant contribution, the foc/el correction
changes the fitted offsets:

dX(off) = dX(on) + 7.5 mm (error about +_ 1mm)
dY(off) = dY(on)
dZ(off) = dZ(on) + 4.5 mm

To correct EVLA data taken with foc/el OFF - i.e. after the
last move and before March 12, use the second table.


-------- FOCUS vs. ELevation ON ---------------------
valid 2007 March 12 to 15.

These offsets will go into the database later (tomorrow?)
after which they should NOT be applied in post-processing.

task clcor; opcod 'antp'; gainver 0; gainu 0;
antenn 13, 0
clcorp  0.020,  -0.005,   0.002; go clcor; wait clcor;
antenn 14, 0
clcorp  0.020,   0.012,  -0.006; go clcor; wait clcor;
antenn 16, 0
clcorp  0.023,   0.019,  -0.015; go clcor; wait clcor;
antenn 17, 0
clcorp -0.009,  -0.015,  -0.014; go clcor; wait clcor;
antenn 18, 0
clcorp -0.002,   0.010,  -0.005; go clcor; wait clcor;
antenn 23, 0
clcorp  0.004,   0.010,  -0.010; go clcor; wait clcor;
antenn 24, 0
clcorp -0.007,   0.003,  -0.002; go clcor; wait clcor;
antenn 26, 0
clcorp -0.019,   0.012,   0.004; go clcor; wait clcor;

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-------- FOCUS vs. ELevation OFF - -------------------

Valid XX to 2007 March 12, where XX = date of last move

ea13 Feb13     ea14 Jan17     ea16 Jan17     ea17 Feb21

ea18 Feb21     ea23 Jan29     ea24 Jan16     ea26 Oct18

task clcor; opcod 'antp'; gainver 0; gainu 0;
antenn 13, 0
clcorp  0.027,  -0.005,   0.006; go clcor; wait clcor;
antenn 14, 0
clcorp  0.027,   0.012,  -0.001; go clcor; wait clcor;
antenn 16, 0
clcorp  0.030,   0.019,  -0.011; go clcor; wait clcor;
antenn 17, 0
clcorp -0.002,  -0.015,  -0.010; go clcor; wait clcor;
antenn 18, 0
clcorp  0.005,   0.010,  -0.000; go clcor; wait clcor;
antenn 23, 0
clcorp  0.011,   0.010,  -0.005; go clcor; wait clcor;
antenn 24, 0
clcorp  0.001,   0.003,   0.004; go clcor; wait clcor;
antenn 26, 0
clcorp -0.010,   0.012,   0.009; go clcor; wait clcor;

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