12meter sband Rfi movies.
24may2
Pulsar timing observation with the
12meter are used to make movies of dynamic spectra and rms/mean by
freq channel.
The observational setup is:
- sband receiver.
- 172 Mhz bandwidth centered at 2278 Mhz
- the rf filter passes 2208 thru 2343 (135MHz) so about
20Mhz on each edge of the band has little signal
- 256 freq channels are used (.67 Mhz resolution)
- sampling is 200 usecs for regular pulsars and 32usecs for
J0437-4715
- 30minutes of data is taken for the 200 usec sampling
(4+ 2Gbyte files). Each 2Gbyte file 409 secs of data
- 15 minutes of data is taken with the 32usec sampling (13+
2Gbyte files) Each 2Gbytes file has 100 secs of data.
Generating the movies.
- Each movie includes observations made for 1 month.
- Movies are made of individual images
- the spectra from a scan are first averaged to 1 row of the
fits files.
- 32 usec sampling, spectra averaged to .66 seconds
giving 1363 averaged spectra for the 15 minutes of data
- 200 usec sampling. spectra averaged to 1 second giving 1800
averaged spectra fort the 30 minutef data.
- dynamic spectra:
- The 15 or 30 minutes of are divided by the median spectra
(to flatten the band pass)
- the image is scaled +/- 3 sigma full scale (using a
robust estimator of mean and rms).
- the top Frame is polA, the bottom frame is polB
- rms/mean spectra
- the rms/mean by frequency channel is computed for each
2GByte file of the scan. These are then over plotted
with polA in the top frame and polB in the bottom frame.
- Each color is data from a separate 2 GByte file.
- A green horizontal line is the expected rms/mean (from the
radiometer equation)
- Note: 200Usec data has 409secs/file. 32usec data has 100
secs/file.
- The title for each frame includes the date yymmdd, pulsar
name, the file number for the first file of the scan, and the
polarization.
Table of movies by month:
Notes:
- the dynamic spectra show that the bandpass shape is not always
stable.
- You can see a region moving from darker to lighter after
being divided by the median value.
- The source B0329+54 seems to have this more than others.
- i don't know if it rfi in that direction or maybe
the change in temperature/rain for this time of day.
- the rms/mean shows some 4 minutes files where the rms value is
higher than normal
- polA tends to have a ramp fro 2250 going up in freq.
- polB had increases around 2250 and 2290.
How best to watch the movies:
- use mpv
- It lets you
- single step forward: (period .)
- single step backwards:(comma ,)
- start/stop movie (space key)
- slow down or speed up movie
- setup the default configuration of mpv to continuously loop
when it hits the end of the movie
- mkdir .mplayer
- cd .mplayer
- vi config
Other locations:
- ben's pulsar processing:
/share/s3453g1/AO12m_data/psr_data/
processing: /share/rfi/rmsp12m/psr/
12meter page
home_~phil