Note: the sband, xband track labels in the plot are reversed.

Intro

    On 06apr16 tsys vs elevation was measured using the mock spectrometers. The setup was:

• 172 MHz bw, 1 second  integrations, mock spectrometers
• xbPolB cfr 8600 MHz, sbandPolA 2270 MHz. taken simultaneously
• az=20 deg, el 6 to 88 degrees. drive 1deg/sec
• time: 11:20 ast, lst:00:00, sun at -10deg dec.
• drive up and down two complete times.

Processing the data:

• input the mock spectra (392 1 second records).
• using the rms/mean by channel, compute a mask of spectral channels with no rfi.
• Compute the total power over the good channel mask.
• Use the center of each 1 sec rec for the data timestamp
• Input the telescope position info from the 12meter logfile.
• Interpolate the measured az,el position to the data timestamps.
• Normalize the total power to the median value between 70 and 88 degrees elevation

Plots of tsys vs el

   
    The plot shows  tsys vs elevation for xband and sband (.ps) (.pdf)

• There are 4 passes over the 6 to 88 degree range (2up ,2 down). They have been over plotted
• Black is sband polA, red is xband polB
• The graphs are normalized to the median value with elevation greater than 70 deg.
• The bump around elevation = 40 deg is at:
• ra=2.79 hrs, dec=61.9 deg. this is the galactic plane.
  
• xband has a 12% change over the 6 to 88 degree elevation range.
  
• above el=45 deg, xband Tsys varies by < 1%
  
• sband has a  20% change over the 6 to 88 degree elevation range.
  
• The beamwidths for the two frequencies are:
  
  • sband: 40 amin
  • xband: 10 amin