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Please enter any significant events related to the AuScope VLBI project, including observations, configuration changes, hardware upgrades etc.
El offset was seen to be 0.215 deg. New model loaded into controller with this offset
Pointing observations show a +0.19 deg offset in El, nothing in xEl. No correction made to model at this stage.
Notes from Brett Reid:
I Drove antenna to position setpoint Az/El -200,10 Randall measured from a point on lower rim of dish to a pont on heatshield edge. 3388mm Drove to Az/El -200,10.1 degrees Measured distance again. 3399mm Determined a change of 0.1 degrees in El produces a 11mm change in length.
The tape measure length method is repeatable. It can be used as another check for elevation offset checks with time.
Repeated finger pressure to encoder coupling torque test. No movement of pin felt and no change in length of rim to heatshield measured while tracking azel -200,10. We have confirmed small pin is tight.
With e-stop engaged the encoder was removed. No looseness of coupling to encoder shaft was felt. Encoder put back on. Adjusted encoder orientation for current elevation position to read as close as possible as before. 0.04 less was the change in elevation reading. Jamie or Jim need to point on a source to confirm this and adjust the offset accordinly. We would have changed parameter 20.21 to produce 3388mm rim to heat shield with position -200,10 (azel) setpoint but I forgot the key parameter and would not have been able to change it.
The current heatshield to rim measurement after commanding -200,10 azel degrees is 3392mm, a change of 4mm after encoder checking/reinstall.
Thanks Randall for doing the checks.
Pointing observations made at X-band, on 9/5/11 after the R4481 experiment. Measured pointing offsets of ~0.08 degrees in El (no significant offset in X-El) on 1921-293 (Az,El = -100, 44) and ~0.1 degrees in EL and ~0.05 degrees in X-El on 30 DOR (Az,El = 156,23). The pointing errors are causing a loss of ~50% of the power at X-band. The pointing errors measured on 5/5/11 previous to R4481 showed no significant errors (<0.03 degrees in El) on Northern sources with slightly worse pointing for Southern sources (~0.05 degrees).
Schedule file yghb2 First good data on all three antennas, nominal pol: 108-0126
01:29 crossed pols
01:45 DBBC spectra look bad! Reconfig!
01:51 OK now but no phase cal tones
108-0207 : crossed pol at Yg
02:08 pols swapped back
108-0213 : direct pol at Yg
Done