chris salter reported jumps in lbw on 04may17
(project v3003). This vlbi project was using circular
polarization (the hybrid was in).
On 05may17 I took some data using lbw. The setup was:
- lbw, linear polarization
- cfr 1404 MHz, bw 25 MHz, lbwfilter #5 (1120 to 1800
- telescope sitting at az=348, grza=12.
- ra; 03:17, dec: 06:29 starting
- interim correlator took 1 second spectral dumps for about
- The total power for each spectra was computed and then
plotted vs time (starting at about 12:41 ast).
- i divided by the median power for each
polarization and then subtracted 1., to put the data
in units of Tsys
the plots show the total power vs
time (.ps) (.pdf)
- Page 1: power vs time for the 4200 seconds of data
- Black is polA, red is polB
- The blue dotted lines show the jumps (about 2% of Tsys).
- Page 2: a blowup of the same data.
- each frame holds about 1400 seconds of data
- the green line is a 0 reference level.
- PolA is jumping by up to 2% of Tsys.
- The jump can last from 10 secs up to 200 secs (in the data
- The level eventually returns to that before the jumps.