p2995: cband pulsars with mocks
Joanna rankin and dipanjan mitra reported
problems with folded pulsar profiles using the cband receiver
and the mock spectrometers.
The setup was:
- 7 mocks each covering 170 Mhz.
- centered at 4070,4220,4370,4520,4670,4820,4970.
- 51 usec spectra, 32 channels, 16 bit recording, no blanking
- Joanna pushed the data through the prsfitstofil (converting ao
psrfits to sigproc filter bank dataformat).
- She then processed the data.
resolution: 18may16: dipanjan contacted me, and said that they
had found a baselining problem in their processing..
Joanna reported dips in the folded profile
before and after the pulse.
She provided a an example
- Pulsar B1237+25, 128 usec sampling,32 channels for each 170
Mhz band, and 7 mocks covering 4-5 ghz.
Dipanjan also sent a plot
showing the problem from 18 and 20 sep2015 (.pdf)
- Page 1: B1929+10 18sep15.. black is total power.. no dips.
- Page 2: B1933+16 18sep15.. black is total power.. dips
up to 10% of pulse covering up to 1/3 of the period.
Looking at the data:
- I took the data for B1933+16 on 18sep15 (this data showed dips
up to 10% of the pulse stretching over 1/3 of the period.
- To process the data :
- input the psrfits spectra from the files number 200,201.(
774 seconds of data..)
- I just used my idl routines. I did not convert the data to
sigproc filter band format.
- compute the total power in polA,B separately
- dedisperion was not done.
- fold each total power time series.
- I took the polyco.dat file that they had on monster0
and computed the period for the middle of the data
- I ended up using 0.35876777 seconds for the period, and
1000 phase bin channels (.358 ms/phasebin)
- The period varied by .03 usecs over this period.
- Using the central period should have broadened the pulse
by less than 40 usecs (less than 1 phase bin channel).
The plots show the folded
data (.ps) (.pdf):
- Page 1: folded profiles for the 7 bands
- black is polA, red is polB jo
- Page 2: blowup to get a closer look at the baseline.
- the peak is about .04 Tsys.
- The vertical scale is +/- .001 Tsys.. or about +/-2.5% of
- No dips are seen
- Page 3: over plot the 7 bands on the same plot.
- top: entire period.
- bottom: blowup channels 200-400 (20% of the period).
- You can see the time shift because dedispersion was not
- the dm is about 158.. the measured shift is close to what
- No dips are seen in total power data folded (with no
- An individual 170 Mhz band should be smeared by less than
- this is less than 1% of the period..
- the 10% smearing data seen in joanna and dipanjan's
data are not seen here..
- It looks like the data is ok.. It must be a processing
- psrfitstofilt or in the processing to get the folded