Reading and Folding ASM Data II
Reading and Folding the ASM Database Over Coffee BreakThe example script found on the SITAR downloads page can be used to epoch fold the entire ASM database over coffee break. Coffee break here being defined as 22 minutes of CPU time, using a 2.8 GHz Intel Core Duo Apple laptop. In this example, for all 381 ASM data files, the data is read in, and then epoch folded over 500 periods (folded into 20 phase bins) logarithmically spaced between 5 minutes and 500 days. Plots are created for lightcurves binned on 7 days, as well as for the epoch folding statistic with linear and logarithmic x-axes.
The basic commands that are run are the following.
To run this code, download the list of ASM
data files. Go to the All Sky Monitor web page and
download all the data files. Note: You might have to modify
the contents of
One of course can custom modify the script. I have run the script using 10,000 logarithmically spaced periods, instead of just 500. This took about 8 CPU hours. Selected highlights presented below.
The 30 day super-orbital period of the low mass X-ray binary and X-ray pulsar,
The 180 day super-orbital period of the low mass X-ray binary,
The 8.965 day orbital period of the high mass X-ray binary and X-ray pulsar,
The following was generated by modifying the driver script used to
fold the ASM lightcurve of Her X-1. Noting the
extremely sharp peaks in the epoch fold results for Vela X-1 above, we have
folded the Vela X-1 lightcurve on the fundamental 8.965 day period. The
results are presented below, using 100 phase bins:
This page was last updated Oct 21, 2020 by Michael Nowak. To comment on it or the material presented here, send email to email@example.com.