Intro

    Data for pointing model4A was taken jul-sep21 (more info). The acquisition included:

• The xband receiver was used for the model (sband had  too much rfi).
  
• az,el strips of 12 beamwidths (great circle) were done tracking sources rise to set.
• spectra were recorded at 7 freq bands, each 172Mhz wide, and spaced by 142Mhz.
• 8135 to 9200 Mhz
• the total power  over the 172Mhz  bandwidth was computed for  each of the 7freq bands (after removing rfi).
  
• 2-d gaussfits  for each cross were done using the total power. The fits gave:
• az,el pointing offsets
• beamwidths in az,el
• src deflection relative to Tsys (no cal was used).

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The results:

    The plots show the results from the fits (.ps) (.pdf)

• Page 1: Source Deflection/Tsys vs elevation.
• There were 8 sources used (although some probably should have been excluded because they were too weak).
  
• The 8647 Mhz band was used for the plots.
  
• Each color is a different source
• The sources the src/Tsys < .01 were 40 Jy or less at xband.
  
• Page 2: Flux used for the sources:
• I used the fluxes provided by chris salter.
  
• There was only 1 value for xband so all of the freq bands used the same value.
• Top: source flux
  
• The black lines shows the flux from chris's file
• Some of the sources were extended. The red line shows the beam diluted flux:
• bmDilutedflux=srcFlux*antBm^2/(antBm^2 + srcWd^2)
• The antenna bm width at xband is 10Amin.
  
• Bottom: ratio of beamDilutedFlux/srcFlux
• 3C144,3C461, and 3C58 have > 20% correction.
  
•  Page 3-6: SEFD vs elevation and azimuth by source
  
• Each color is a different frequency band.
• There are 2 frames/ source
• top frame: sefd vs elevation
• 2nd frame: sefd vs azimuth
• the flux: xx yy  in the title has the total flux (xx) and the beam diluted flux yy.
• Page 7: sefd vs elevation all sources
  
• The median sefd over the 7 frequencies was used for each cross.
• each color is a different source
• the dashed horizontal line is at 4000 Jy.
• Top: all sources
• 3C273  is a large outlier with lots of scatter
  
• bottom: 3 source with fluxes 200 to 500Jy
• There is less scatter in these 3 sources
• 3C144 and 3C461 are more extended (9'x45', 5') while 3C405 is more of a point source for our 10' bm (96")
• using 3c405 the sefd looks to be around 4200 Jy.

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SUMMARY:

• 8 sources at xband were used to make model4A
• the 2d gauss fits gave parameters that allowed us to compute the SEFD.
• a single flux  was used for all 7 freq bands.
• the flux used was corrected for beam dilution
  
• 5 sources with flux <= 40Jy gave source deflections of 1% tsys or less
• The sefd from these sources showed lots of scatter
• 3 sources with flux >200 Jy had much less scatter
• The sefd (at higher elevations) looks to be around 4200 Jy.