A2351: xband HE rrl's
06jul08
Intro:
A2351 is doing 300 sec on,off position switching
with the xband receiver.
Pointing/calibration checks:
Pointing data taken 20jun08->30jun08 showed a 5
asec offset in the za errors. On 01jul08 15:00 hours I modified the
xband pointing model to remove a 4 asec offset from the constant za
term. The
The plots show the
pointing and calibration checks (.ps) (.pdf):
- Page 1: calibration. Gain, Tsys, Sefd, and avgBeamwidth for all
the data
- B1622+238 shouldn't be used for pointing or gain checks at
xband. It has a width of 24 asecs which is close to the beam width.
- B1607+268 at za=13 was taken on on 02jul08. For some reason
this pattern had about 1/2 the gain of the 3 other patterns for this
source before transit. The fit for the 4th board didn't converge at
all.
- The pointing error for the 3 boards that did fit is close
to 0.
- I looked at the tiedown tensions since it was at az=131
which is close to pointing at td4, but the tensions did not go to zero.
- Page 2: coma, 1st sidelobe, beam efficiency(main beam), beam
efficiency (main Beam + 1st sidelobe).
- The coma is large at hi za. This is probably coming from the
shimming of the za rails.
- B1622+238 should be ignored because it is extended.
- Page3: pointing errors all data:
- 1,2nd plots: za errors vs za and az.
- 3rd,4th plots: az errors vs za,az
- Page4: pointing errors 30jun08. Prior to 01jul08 the za
Errors have a mean offset of about 5 asecs.
I removed 4 asec from the model on 01jul08 15:00.
- Page5: pointing errors after 4asec offset removed in za constant
term. The offset is now close to zero .
- Page6: pointing errors vs az,za. The length of the tick mark
is
proportional to the pointing error. 1 tick mark is 5 asecs. The
direction of the arrow is the direction of the error.
processing: usr/a2351/chkpnt.pro
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