Gps L3 in a2010 data jan09-mar09

• Search the rms database computed each month. This holds the rms/mean for each scan taken by  a2010.
• Choose scans who had large values in the rms around 1381.05 MHz.
  
• Make images of these scans and pick 11 scans that had:
• strong values of gps l3 --> it came closer to the beam.
• Pick some scans where the sidelobes extended over  +/- 15 MHz.
• pick some scans where the signal was weaker but it lasted for a  long time.

Data taking:

• The 7 beam, dual linear-pol alfa receiver is used. It has a system temperature of about 28 Kelvins.
  
• Each beam is 200 arc seconds. The 7 beams cover about 10 arcminutes on the sky.
• The receiver is centered at 1385 MHz and a 100 MHz Bandwidth is used.
• The telescope sits at the meridian during datataking.
• The wapp autocorrelator is used for datataking.
• Spectra are integrated for 1 second using 4096 channels. The spectral resolution is 48 Khz after hanning smoothing.
  

Data processing:

• Dynamic spectra were made of the 4096 channel by 600 second data sets.
• The image is divided by the median value to flatten the band pass
• The image is scaled so that  full scale (min to max brightness) is +/- 2% of Tsys (+/- .6 kelvins).
• The image has been averaged by 4 in frequency (didn't have that many pixels on my display!!).
• Individual spectra:
• Individual spectra showing gps l3 were  1 second in duration. They were normalized by adjacent spectra that did not include gps l3.
  
• Peak power in the gps l3 band
• The peak power in the frequency channels 1380.3 to 1381.8 was found for each 1 second spectra (this has the 48 Khz Resolution).
• The 600 second points were then divided by the median value to normalize it to the average spectral density (note the 500 second long gps l3 scan used the 100 seconds when gps l3 was off for the normalization).

The strongest signal 20jan09.

• On 20jan09 around 3:18 am (ast) the largets gps l3 value was found
• It has a peak value of 140 times the average spectral density (both used 48khz rbw).

• The image has 3 separate bursts.
  
• 3 peaks with lots of sidelobes occured at 10,84, and 120 seconds.
• that Large signals occurred at 10,84 and 120 seconds
• The sidelobes extend from 1360 to about 1395 MHz.

• Page 1:
  
• top: peak power near 1381 MHz. At 84 seconds polB got to 130 * Tsys.
• Middle: blowup up the vertical scale. The burst at 350 seconds lasted for 41.5 seconds and was about 5% of the average Tsys.
• Bottom: blowup horizontal and vertical.
• Page 2: average spectra second 84 for the 7 beams.
• beam 5 had the strongest signal.
• Page 3: blowup vertical scale for second 84 7 beams.
• You can see the sidelobes clearly out to the edge of the plot
• Page 4: Blowup second 84 beam 5 ..
• The dynamic spectra above used beam 5b (red trace). This is a blowup of the strongest signal.

Other days with strong signals:

• 06jan01 (.gif)
• 12jan09 (.gif)
• 20jan09 (.gif)  scan that followed the 20jan09 scan above.
• 02feb09 (.gif)
• 03feb09 (.gif)
• 07feb09 (.gif)
• 09feb09 (.gif)
• 15feb09 (.gif)
• 21feb09 (.gif)
• 22feb09 (.gif)
  
• 30mar09 (.gif) this scan was weak but lasted for almost the entire 600 seconds.

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