On 07jul21 the sun was tracked with the 12meter
telescope for 1 hour using the xband receiver.
The setup was:
- The jpl horizons ephemeris was used to track the center of
the sun (with an offset)
- The telescope was offset: .125 deg Az, .124 deg El
(great circle) from the center of the sun.
- data taken starting at 16:04:10 AST.
- xband receiver was used.
- Mock spectrometer was used to record the data.
- 7x80 MHz bands were taken centered at:
- bands spaced by 72MHz so a 4 MHz overlap on each side
- 2 pols, 8192 channels/pol, 21 KHz channel width
- 16 bits spectra were recorded.
- the mock rms levels were set to 20 sigma (to hopefully
give us some more headroom on the mocks).
- spectra dumped every .002048 seconds
- The datataking script can be found in:
We were looking for micro bursts on the sun.
- Total power:
- the total power was computed over each 80MHz band. No
rfi removal was attempted
Plotting total power vs time
The first plots show the total
power vs time at 1 second resolution (.ps) (.pdf)
- Page 1: 1 hour of data
- Each total power series has been normalized to its
median value on the sun.
- Each color is a separate 80 MHz band
- offsets have been added for display purposes.
- The data has been averaged to 1 second resolution.
- The x axis is seconds from 16:04:10 ast (start of
- Top: polA,
- Bottom: PolB
- The vertical strips show where each data file begins
(there were 26 2gb files for each band).
- there is a jump in the total power for all bands around
1860 seconds after the start. It stays high for about 100
- about 300 seconds before the jump, the noise level
- Page 2: blowup around the total power jump
- still 1 second time resolution.
The next plot shows the total power
vs time around the jump at 2ms resolution (.ps) (.pdf)
Looking at the total power dropouts
The first set has a blowup of the total power vs
time showing dropouts (.ps) (.pdf)
- The time series is from the 8456 MHz band with 2 ms
- Top: polA
- Middle: polB
- you can see some periodic dropouts.
- The dropout at 225.69 seconds is over plotted
- Black has all 7 80MHz bands for polA
- Red has all 7 80 MHz band for polB
- The dropout is the same for all 7 80 MHz bands
- The dropout occurs at the same time for polA and polB
- there dropouts in polB occur much more often.
Spectrum of the total power dropouts
The plots show the spectrum of the total power
during the dropouts (.ps) (.pdf)
- Top: full 250 Hz bandwidth.
- red:polB (I've added an offset for display)
- Middle: blowup of polB out to about 80Hz.
- polB spectra around 79 Hz.
- The green lines are multiples of .5 Hz
- The red dashed line is the measured comb (at 79.520368
- at 79.5 Hz the offset from the .5 Hz comb is
- The comb freq is then (.0204/(79.5*2)) .500128 Hz... so
it is not locked to our station clock.
- Data was taken for 1 hour while tracking the sun
- we saw a increase in total power (10% of the tsys on
sun) that lasted for about 100 seconds. T
- This is probably a burst on the sun.
- We saw dropouts in the total power
- They occurred more often in polB then polA
- the lasted for about 10 millisecs
- They dropouts were the same for all 7 bands (not freq
- The dropouts were periodic. period: .500128 Hz
- Felix pointed out that this is probably the dithering of
the fiber optic transmitter.