mar11: Pointing errors in 800 rcvr
The 800 MHz antenna was reinstalled in sep10.
Calibration scans from sept10, jan11, mar11 were used to check the
pointing offsets. During this time period the platform reinforcement
was also taking place. The important dates are:
The plots show
the 800 MHz pointing error for the sep10 thru 11mar11 timeframe (.ps)
- 11sep10: diagonal beam reinforcement starts
- sep10 : dual pol antenna (version 1) reinstalled
- 26sep10: calibration data taken
- 13oct10: diagonal beam reinforcement finishes.
- 18nov10: reinforcement of vertical members begins.
- 20jan11 : calibration data taken
- 05feb11: reinforcement of vertical members finishes.
- 9,10mar11: calibration data taken
- 11mar10: 2 screws holding the 800 rcvr were found to be loose.
screws were then tightened.
- 11mar10: calibration data taken.
The table below shows the mean and rms errors from
the various datasets:
- page 1: all data 26sep10 thru 11mar11.
- The 4 frames are: za error vs za, za error vs az, az error vs
za, az error vs az.
- page 2: 26sep10 data
- page 3: 20jan11 data
- page 4: 9,10,11 mar11 data
- page 5: overplot the data from the different dates.
- the 26sep10, and 20jan11 have a ramp in zaerror vs za.
- the mar11 data does not show this.
|za error (asecs)
|az Error (asecs)
The same sources were tracked 10mar11 and then 11mar11 (after the feed
bolts were tightened) to see if the pointing had changed.
The plots show
the difference in pointing errors for the two days (.ps) (.pdf):
- Top: the change in the azimuth error (after - before) screw
- Bottom: the change in the za error (after - before) screw
- The screw tightening did not have a large affect on the pointing
- The 800 MHz rcvr has had a large offset in za (-25asecs) since it
was remounted back in sep10 (the offset was not present back in dec09
when the single pol feed had been installed).
- 2 loose screws were found in the mounting of the 800 MHz feed on
11mar11. They were tightened. They did not have a large affect on the
- 14mar11 the 800 MHz rcvr model was updated:
- a -25. asec offset was subtracted from the model za
- a 5 asec offset was subtracted from the model az constant value