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Get Pflux



get_pflux( burster [, instr_list] )

  • burster is either an internal identification number, or a string representing the burster's name.
  • instr_list is a string containing a list of instruments, separated by commas. The recognized instrument names are given in Table 1. This argument is optional; if it is omitted, it defaults to "PCA, SWFC".


This function calculates the Eddington flux of the LMXB by looking up the flux and uncertainties of every PRE burst observed from that source by thespecified instruments. It then fits a constant value to all the data, weighted by the inverse square of the errors on the data points. The method is the same as the one detailed in Appendix A of Worpel, Galloway & Price (2013).


The function returns a struct consisting of the following members:

  • SOURCENAME- the name of the source
  • INSTR_NAME- an array of n strings, where n is the number of instruments listed in instr_list, in the same order.
  • N_PRE- an array of n integers, the number of PRE bursts observed from the source by that instrument.
  • F_EDD- A float. the Eddington flux calculated for that source.
  • F_EDD_ERR- A float. the 1σ error on the Eddington flux measurement.
  • CHISQDF- A float. the reduced χ2 of the constant fit.
  • FLAG- An array of 9 integers, set to 1 if the corresponding condition in Table 2 is met, 0 otherwise.


If an unknown instrument is specified, the string ”(unknown)” is appended to its name in INSTR_NAME, as well as flag number 3 being set. If no PRE bursts were found, then F_EDD, F_EDD_ERR, and CHISQDF are given the sentinel value -1000 and flag number 0 is set. If only one PRE burst was found, then F_EDD and F_EDD_ERR are given the peak flux and uncertainty on that measurement, and CHISQDF gets the sentinel value -1000, and flag number 1 is set. The bimodality in peak fluxes from 4U 1636-536 is not taken into account; this may change in later versions.

EXAMPLES An example of matching by source name and explicit specification of instrument:

IDL> x= get_pflux( ’1820’, ’PCA’ ) & print, x
4U 1820-303 PCA
60.792187 2.7534075 1.4194896
0 0 0 0 0 0
An example of searching by source number; no instrument list defaults to ”PCA,SWFC”:

x= get_pflux( 15 ) & print, x
1724-3 PCA SWFC
3 23
61.684956 12.430897 6.4515909
0 0 0 0 0 0


Table 1: instrument list
PCAPCA instrument on RXTE 
SWFCWide Field Camera on Swift 
LBCLong Burst CatalogA manually compiled list of long-duration bursts
Table 2: FLAG values
FLAG valueDescription
0Unknown source
1No PRE burst has been observed from any specified instrument
2Only one PRE burst has been observed by all specified instruments together
3One or more instrument names were unrecognized
4One or more bursts had no associated error bar; defaults to 25% of the measurement
5High χ2 indicates inconsistent with constant F_Edd
6Low χ2 indicates error bars may be overestimated
7RXTE database does not recognize this burster
8SWFC database does not recognize this burster
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Page last modified on October 08, 2013, at 05:06 AM