Intro  top

• data was taken 16:48 till 07:06 . 7 sources (not all full tracks)
  
• Page 1: az, za covered
• Page 2: gain,Tsys,sefd, average beam width
• gain: avg of about 9K/Jy
• Tsys: around 25K
• sefd: about 2.5Jy
• beamWidth: 120 asecs
• outliers
•  B0618+145,B0831+171 had large fluctuations in gain and Tsys.. but the sefd was relatively stable
• There was lots of low level in band rfi (at 2380) during the run (i could see it on the spectra).
  
• The cal measurement was probably affected by the rfi.. but the source and Tsys were  ok.
• the sefd cancels the cal value... so it was stable.
• B1218+339: low gain,low tsys,  low sefd, and large beam width..
  
• Not sure why this occurred. The source is no extended...
• Page 3: coma, sidelobe height, main beam efficiency
• values look normal
• Page 4: pointing errors:
• frame 1,2: za errors vs za, az
• frame 3,4: az errors vs za,az
• zaErr: mean: .27, rms 3.73 asecs
• azErr: mean: -1.4, rms 5.76 asecs
• these are reasonable values for the current state of the pointing model
• there are a few outliers  (see  page 5)
• Page 5, az,za errors, az,za position, and tiedown tensions
• I've flagged some of the pointing error outliers (to line them up in the different plots)
• the outliers a little before 20 hours:
  
• these occurred on source B0331+171.
  
• The problem was probably rfi..
• The outlier at 26.7 hours...
• this was at transit for B1615+212. This was at transit.. za< 3deg.. The model is not very good at za=3 deg..
• Something happened between 25 and 26.6 hours.. no data was taken (although the source was up).
  
• I didn't see any notes in the operator log. but it looks like the telescope wasn't tracking ??
  

22apr16: lbw calibration run results (.ps) (.pdf)

• data was taken 16:30 till 01:30. 6 sources (some only a few crosses/source)
• These were a subset of the sources taken with sbn on 21apr16. since the observing time was shorter, not all sources were covered.
• Frequencies used: 1155, 1310, 1375, 1415 MHz
  
• page 1: az , za coverage
• page 2: gain,tsys,sefd, beamwidth
• The gain and Tsys are higher than normal (see sysperf  by month, for last lbw data)
• The SEFD is normal. This says that the cal values are wrong (since the sefd ration Tsys/gain cancels the cal value)
  
• The daily tsys measurements have also been high 38 -> 40k.. (for all the diode combinations).
  
• so we have a problem with the lbw cals.
• A larger tsys means the actual cal power has decreased..
  
• Since it occurs with all cal values, it may be a loose connection.
• Felix has checked the cables from cal chassis to dewar input and he said they were ok
• It could be a cable inside the postamp/cal chassis. If so, it would need to be one of the cables common to all of the cal switching combinations.
  
• We need to check the cables and then remeasure the cals
• There is no jumping around of the gain (like sbn).. no rfi present  in the bandwidth used.
  
• Page 3:
• coma, sidelobe height, eta main beam, eta mainbeam + 1st sidelobe
• normal values.
• page 4: pointing errors:
• frame 1,2: za errors vs za,az
• frame 3,4: az errors vs za,az
• values:
• za Err: mean=-1.47, rms: 4.65 asecs
• az err: mean =-.9,    rms: 4.09 asecs
• typical values for current state of the pointing model
• page 5: az,za errors, az,za position, and td tensions..
• I've put a blue dashed line at some of the pointing outliers to line them up between frames.
• 19.8 hours: low za ..2deg..
• 20.5 hours: high za (> 19 deg)
• 23.5 hours: source rising, no tension in tiedown 8 (green trace bottom)

SUMMARY:

• pointing error:

• 	Az error (Asecs)		za error (asecs)
  	mean	rms	mean	rms
  sbn	-1.4	5.76	.27	3.73
  lbw	-.9	4.09	-1.47	4.65

• I left the outliers in the average.. removing them would decrease the error (especially sbn with the rfi).
• sbn
• constant birdie around 2390 MHz. we've seen this in the hilltop monitoring system (more info)
  
• broad band lowerlevel  rfi covering 2380 MHz
  
• The rfi came and went.. this rfi has previously seen.. it has an az, za dependence.
• lbw:
• the cal output power has decreased since before the shutdown

processing: x101/160422/x101.pro

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home ~phil