Data Processing School :: Exercise PSR 03
Source directory | /data/lofarschool/data/Exercise-PSR-03 |
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Contact person | Jason Hessels |
Context
Illustrates an important technique for characterizing RFI, finding binary pulsars, as well as other science like planets and flare stars.
Prerequisite
Exercises PSR-01 and PSR-02 and knowledge of what a dynamic spectrum shows.
Description
In this exercise, the user will create a dynamic spectrum from timeseries data and interactively inspect it for a pulsar signal and RFI. This is one way in which binary pulsars (who’s signal is Doppler shifted) can be detected, but it also gives a way to characterise other pseudo-periodic interfering sources. Also important technique for other science like planets and flare stars.
Files & Directories
DATA:
B0809+74_081220_4tiles_DM6.12.dat: LOFAR timeseries (all observed subbands dedispersed and added)
B0809+74_081220_4tiles_DM6.12.fft: a power spectrum of the timeseries
B0809+74_081220_4tiles_DM6.12.inf: required header info
Ter5_03Oct04_DM238.00_350s.pick: a dynamic spectrum of data from the globular cluster Ter5. There are at least a dozen pulsars to see in these data (look at the dynamicfftsearch.py for a list of their spin frequencies).
Ter5_03Oct04_DM238.00_350s.inf: required header info
SCRIPT:
dynamicfftsearch.py: the python script that creates a dynamic spectrum. Feel free to tweak this if you know some python.
SAMPLE OUTPUT:
dsp_346.00.ps: a dynamic spectrum showing the binary motion of the 2-hr eclipsing pulsar Ter5A.
OTHER:
COMMANDS.txt: some sample commands that the user can run
PULSAR_ENV: necessary environment variables (bash shell assumed)
Step-by-step instructions
- To create a dynamic spectrum with a given central frequency and sub-int length:
python dynamicfftsearch.py 3.0 310 0 B0809+74_081220_4tiles_DM6.12.dat
- To move left or right in this dyn. spectrum: type “,” or “.”
- To print the current window: type “p”
- To view the eclipsing 2-hr binary pulsar Ter5A (data from GBT):
python dynamicfftsearch.py 86.5 350 1 Ter5_03Oct04_DM238.00_350s.pick