xband plots
3GHz plots

Intro

    Shims were used to move the wideband horn closer/farther from the secondary to search for the focal point.  The shims were 1" thick.

• We went from 0 shims to 5 1" shims.
  
• Each shim moved the horn 1" closer to the secondary.
  
• With 2 1" shims used, the mouth of the horn was 22.6" from the center of the secondary.sa
• Sandy's paper said that the focus moved  by 5 cm from 2GHz to 12 GHz.
  
• At each shim position 16 hours was spentdoing crosses on :
  
• M87,CygusA, CasA, and occationally the crab.
• Crosses were done using the xband filter : 8060 to 9150 MHz
• for the 2,3,4,5 " shims we also did crosses using the 3GHz filter : 2750 to 3450 MHz.
• a 10 sec calon,off was done prior to each cross.
• Data acquisition was  done with the mock spectrometers.
• xband: 7x 172MHz bands  spaced by 142 MHz
  
• 3ghz:    5x 172MHz bands spaced by 142 MHz
  
• 1024 channels 167Khz channel width
• .1 second integrations.
  

more info:

•   circular quadruple-ridged flared horn.akgiray,weinreb (2012)

Dates for data taking:

date	#shims/distance to secondary	freq
230529	2, 22.6"	xb
230531	1, 23.6"	xb
230601	0, 24.6"	xb
230602	2, 22.6"	xb
230603	2, 22.6"	xb
230604	2,22.6"	3ghz
230607	3, 21.6"	xb
230608	3,21.6"	3ghz
230609	4,20.6"	3ghz
230610	4, 20.6"	xb
230611	4, 20.6"	xb
230612	4, 20.6"	xb
230613	4,20.6"	3ghz
230614	5,19.6"	xb
230615	5,19.6"	3ghz
230616	5,19.6	xb
230617	5,19.6	xb
230619	4,20.6"	xb

Processing:

• A cross consisted of an azimuth strip (great circle) followed by an elevation strip.
• each strip was about 6 bms long
• the data was converted to kelvins using the cal.
  
• 6 separate 2d gaussfits were done for each cross.
• include Tsys in  the 2d gauss fit.
  
• fit stokes I, polA, polB separately
• remove linear baselines forthe  az, el strips before doing the 2d fits
• fit stokes I, polA, polB separately.
• In this case the central average of the az,el linear fits was used as tsys.

plotting the results:

    Plots were made for each 172MHz freq band.

• For xband there were 7  172 MHz bands
• for 3GHz there were 5 172 MHz bands
• Each source is plotted with a separate symbol
• Each shim position is plotted in a separate color.
• Plots are made with data plotted vs elevation and then azimuth
• A 2nd set of plots is made limiting the data to 3C405 and 3C274 with shims 2-5.
• This gives a blownup view of some of the data.
  
• Each page has 3 frames:
• Top: stokes I
• middle : polA
• bottom : polB
  

Each plot has 8  pages

• Page 1: Tsys vs elevation
• Page 2: Gain (K/Jy) vs elevation
• Page 3: SEFD vs elevation
• Page 4: Azimuth bmwidth vs elevation
• Page 5: Elevation Bmwidth vs elevation
• Page 6: AzBmWidth/ElBmWidth ratio vs elevation
• Page 7: azimuth pointing err vs elevation
• Page 8: elevation pointing err vs elevation.

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xband plots

freq (MHz)	all shims vs elevation	all shims vs azimuth	2-5" shims vs elevation	2-5" shims vs azimuth
8223	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
8363	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
8505	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
8647	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
8789	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
8931	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)
9073	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)	(.ps)  (.pdf)

We observed some shim positions on multiple days. The above plots show that there can be a lot of variation in tsys on different days (from the weather).
To  try and exclude variations caused by weather:

• For those shims spacings that were measured multiple times, i went thru and chose the day that had the best sefd.

The table below replots the data using 3C405 and M87 , shim spacings 2" to 5"  and only using the "Best day" for those shim spacings
measured multiple times.

Using "best Day" for multiple shim measurements

freq (MHz)	2-5" shims vs elevation	2-5" shims vs azimuth
8223	(.ps)  (.pdf)	(.ps)  (.pdf)
8363	(.ps)  (.pdf)	(.ps)  (.pdf)
8505	(.ps)  (.pdf)	(.ps)  (.pdf)
8647	(.ps)  (.pdf)	(.ps)  (.pdf)
8789	(.ps)  (.pdf)	(.ps)  (.pdf)
8931	(.ps)  (.pdf)	(.ps)  (.pdf)
9073	(.ps)  (.pdf)	(.ps)  (.pdf)

XBand Notes:

• 3C405 (cygnusA) probably has the most reliable results:
• casA is extended and the flux varies with time
• M87 is not very strong at xband.
  
• Page 1:Tsys
  
• increases as we move push the horn closer to the secondary with the shims
• this is  expected since the edge taper goes down, increasing the spill over from the ground.
• The tsys,gain  may be hi/low depending on any errors in the cal.
• The sefd will not be biased by errors in the cal.
• We redid the 4" shim measurements 3 times. On one day we see a large Tsys increase that may have been clouds/rain.
  
• Page 2:Gain.
  
• the gain increases as we move 0 shims (24.6 inches) to 4 shims (20.6 inches) from the secondary.
• 3 shims (21.6) to 4 shims(20.6") had the gain change .0115 K/Jy to .015 K/Jy ( a 30% increase). So we probably need a 5th shim.
• Page 3:SEFD:
• 12,000Jy at 24.6 inches to 2800 Jy at 20.6 inches
• going 21.6 to 20.6 " the sefd decreased from 3500 to 3000 or about 14%..so the increasing Tsys is offsetting the gain increase a little.
• Page 4,,5: azimuth , elevation beam widths
  
• PolA azimuth beam with is narrower than polb azimuth beam width
• when going 21.6" to 20.6" PolA beam width does not change much, polB beamwidth decreases.
• PolB: this is the opposite of polA
• polB elevation beamwith is narrower than polA beamwidth.
• The 2d fits do not try to rotate the elliptical beam to the major minor access
  
• i removed this with the old receiver since the beam seemed to be circular and the rotation was giving results based on the noise.
• I may need to check if the beam is elliptical
• Page 6: azbmWidth/ElBmWidth ratio
• PolB seems to have more scatter than polA.
• Page 7,8; pointing error in az,el direction
• this error is relative to the pointing model made with the old receiver
• The elevation error is decreasing as we move the horn closer to the secondary.

processing:

• x101/230529/cross, 230532/,230601,230602/,230603/,230607/,230610/xbcross.pro
• x101/12meter/comm/shimproc.pro

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3 GHz plots

freq	all shims vs elevation	all shims vs azimuth
2846	(.ps)  (.pdf)	(.ps)   (.pdf)
2988	(.ps)  (.pdf)	(.ps)   (.pdf)
3130	(.ps)  (.pdf)	(.ps)   (.pdf)
3272	(.ps)  (.pdf)	(.ps)   (.pdf)
3414	(.ps)  (.pdf)	(.ps)   (.pdf)

3GHz Notes:

• the 3414 band has lots of rfi on the high end (5g) so i had to exclude about 1/2 the band
• Page 1: Tsys:
  
• the 4" shim: 20.6" Tsys is similar to the 22.6" value although it turns up around 60deg el. I'm repeating the 4" measurement to see if this holds up.
• Page 2: gain.
• The gain increased when moving from 22.6" to 20.6". We might have expected it to decrease if we had gone out of focus
• When inserting the shims, they had to disconnect and then reconnect the cal cable, so it may have changed a little.
• Page 3: sefd
• the sefd for 20.6" is as good or better than the 22.6" position.
• Page 4,5,6: beam widths and ratio
• the beam widths  do not change with the shims.
• they also don't have the polA,PolB difference that we saw with xband.
• Page 7,8: point errors
• the pointing errors look a bit different  el 20-40 deg. this may be from not tracking the source rise to set with 3 shims and we're just seeing 1 side.

Processing:  x101/230604,09,13 / wb3cross.pro
                    x101/12meter/comm/shimproc_wb3.pro

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