point error after rcvr reinstalled after ao19

sep 2013

     The receivers sbw, cband, and cband hi were removed in jul13 for the ao19 installation. These receivers were reinstalled in the dome after ao19 was removed (on 06aug13). x102 calibration runs done 19aug13 thru 31aug13 were used to check the pointing on these receivers after the re installation.
    The table belows show the receivers and number of patterns taken:

receiver	number of x102 patterns
sbw	196
sbn	86
cband	414
cband hi	202

Note the sbn was not removed for the ao19 testing.

The plots show the pointing errors for the 4 receivers taken 19aug13->31aug13 (.ps) (.pdf):

each page is a separate receiver:

page 1: sbw, page2 sbn, page 3 cband, page 4 cbhigh
the top two frames plot the za error vs za an azimuth
the bottom two frames plot the az error vs za an azimuth
between frames 1 and 2, the mean and rms error for each receiver is printed
pages 5,6 show the pointing error before and after the model update.

Black is before the change, red is after.

If the receiver was reinstalled i little off, there would be an azimuth or zenith angle offset.
The table summarized the mean and rms offsets for the measurements

rcvr	za errors (asecs)		azimuth errors (asecs)
	mean	rms	mean	rms
sbn	1.9	2.9	0.5	6.0
sbw	-8.6	3.7	0.1	5.7
cband	-7.9	3.5	-1.3	5.4
cbandhi	1.4	2.5	1.8	4.6

sbw and cband have relatively large za offsets.

At first i thought this might be a problem from the draglink re installation (since that could affect the za error).

but cband hi and sbn did not show the same offset, so this is probably a re installation error.

In the za direction i think the plate scale is about 38 arcsecs/inch.

This error would be about a .2 inch error in the radial direction of the feed installation.

On 10sep13 i updated the za constant term ( in the pointing models for sbw, cband) to correct for this error.

cband za constant : -86.0 => -78.13 asecs
sbw za constant: -94.46 -> -85.86 asecs

processing: x101/130910/chkpnt.pro

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