Automark

This package implements a method for modeling photon counts collected form observation of variable-intensity astronomical sources. It aims to mark the abrupt changes in the corresponding wavelength distribution of the emission automatically. In the underlying methodology, change points are embedded into a marked Poisson process, where photon wavelengths are regarded as marks and both the Poisson intensity parameter and the distribution of the marks are allowed to change. The details is given in Wong et. al. (2016).

Installation

This package can be installed via function install_github in R package devtools:

install.packages("devtools")
devtools::install_github("astrostat/Automark")

We plan to upload this package to CRAN in the future. That is, future installation can also be done by install.packages("Automark") within R.

Example

library(Automark)       # load library
data(dat)               # load example data
out <- spec.tbreak(dat$x1, dat$x2, dat$y, dat$A, dat$delta.t, dat$delta.w, cpus=5)
plotspec(dat$x2, out$best.fit[[1]])
plotspec(dat$x2, out$best.fit[[2]], np=F, col="red")

References

• Raymond K. W. Wong, Vinay L. Kashyap, Thomas C. M. Lee and David A. van Dyk (2016). Detecting Abrupt Changes in the Spectra of High-energy Astrophysical Sources. The Annals of Applied Statistics, 10(2), 1107-1134. [Journal] [arXiv]