Crosses on the moon were taken on 08apr16.
The setup was:
- 2degree cross length, .01 deg/sec (xb fwhm=10.1amin, sb
- This was set to match the xband beam. The sband beam was
bigger than the moon (30amin).
- mock spectrometer recorded the data: 172 mhz bw, 8192
channels, 1 second dumps, cfr: 2270, 8600.
- jpl horizons ephemeris to track the moon.
- 6 crosses in az,el were made.. from el=48 to el=40 deg.
- The moon was close to phase=0 (new moon).
Processing the data:
- The spectra were input and an rfi mask was made to exclude
rfi (rms/chan, fit polynomial, and then clip)
- Total power was then computed for each second of data
(using the rfi mask to exclude data).
The plots show
the results of the measurements (.ps)
- Page 1: total power strips
- top Frame: total power from the 6 strips are plotted vs
- black is the az strips, red is the el strips. The
dashed green lines are the start of a cross
- the y axis is linear in power.
- 2nd Frame: total power strips for crosses for sband.
- Bottom: strips normalized to Tsys vs strip offset.
- For each strip an 1st order polynomial was fit to the
edges of each strip (10% each side). This linear fit was
then used to normalize each total power point to Tsys.
- Black, red: xb az,el strips
- green, blued: sb az,el strips
- the dashed yellow line is the center of the strip:
- The xb el strips have an increasing value as the move
from low el to high el across the moon.
- Page 2: Moon deflection in units of Tsys.
- top: xband Moon deflection (in units of Tsys) plotted vs
- black is the az strip values, red is the el
- For each az strip i fit a 2nd order polynomial and
took the peak value as the center of the strip.
- This was within 1 sample of the center (.01 deg,
.6amin). so the ephemeris tracking was working
- Since the el strips had a ramp, i used the 10 points
about the center for the average el value.
- The green line is the average of the az,el values (in
units of Tsys)
- middle: sband moon deflection (in units of Tsys) vs el.
- Bottom frame: Tsys computed from measured parameters:
- I got the aperture efficiency and expected tsys from :
"The auscope geodetic VLBI ARRAY", j.e.lovel, journal of
geodesy, feb 2013. They have similar patriot 12m
telescopes, with the same receiver setup.
- The moon temp was take from: "Observing the moon at
microwave freq using a large diameter deep space network
antenna", david d morabito, ieee transactions on
ant and propagation: vol 56, no3, mar2008.
- The phase of the moon was close to 0 (it doesn't make
much difference for sb or xband.
|12m aperture efficiency
|from auScope computation.