sbn calibration after m8-4 cable repair
The 13jan14 earthquake damaged cable m8-4. The
repair was finished on 11mar14. X102 calibration runs were done 11
and 12mar14 to see how the pointing and gain were.
- a tilt sensor run was done prior to the calibration run to
check the 1az tilt of the platform.
- The calibration runs used: the sbn receiver, the interim
correlator, and the standard x102 heiles calibration
- The tiedowns were tracking the average height of the platform
during the runs.
- The weather was overcast 11mar14 and a light drizzle on the
start of 12mar14
The plots show the results of the
measurements (.ps) (.pdf):
- Page 1: az,za tracks across the dish.
- I limited the data to > za=2 degrees. The data below that
had pretty bad pointing errors (because the model was never
very good down there..).
- Page 2: pointing errors vs az,za
- top 2 plots: za error vs za,az
- bottom 2 plots: az errors vs za,az
- the mean offsets were :.17,-.52 in za,az
- the mean rms's were: 3.24, 4.91 asecs in az,za
- B0518+165 (3c138) seems to have lots of outliers.
- This was the first source taken on 12mar14.. when it was
- Page 3: arrow plot of pointing errors.
- The length of the arrow is proportional to the total
pointing error (1 tick mark is 5 asecs).
- the direction of the arrow is the direction of the pointing
- Page 4: gain,Tsys,sefd, beamwidth
- the red boxes (B1442+101) and the purple boxes (B0824+294)
look like they have fluxes that are a little low:
- the gain is low for these, the sefd is high, but tsys is
the same as the others.
- Some of the beamwidth fits for B0518+165 (black +)
seem to be off.
- Page 5: plot gain vs azimuth.
- This was to look at the difference between the southwest
fill area (110-140) to see if it was lower.
- previous higher frequency receivers showed a dropoff
in this area. sbn does not show a large difference.
- Page 6: coma, sidelobeheight, beam efficiencies...
- Pointing error: za: 3.24 asecs, az: 4.9 asecs: total error:
- sbn gain: about 10 K/Jy (out to za=15).
- The telescope scope is performing similar to before the
- Not changes will be made in the pointing model.