Gamma-Ray All-Sky Imaging with the Burst and Transient Source Experiment
Abstract
The BATSE mission aboard CGRO monitored the whole sky in the 20 keV - 1 MeV energy band continuously from April 1991 until June 2000. Although BATSE had very poor intrinsic angular resolution, the data can be used to survey the entire soft gamma-ray sky with < 1 degree angular resolution and ~ 1 mCrab sensitivity by using the Earth occultation method. This method determines flux by measuring the step in the count rate profile in each BATSE detector as a source rises above or sets below the Earth's limb. A maximum likelihood imaging technique can then be used to build up all-sky maps from the images of the Earth's limb produced by occulting sources. However, since the Earth seen from BATSE has a radius of ~ 70 degrees, the limb images that intersect at the positions of bright point sources have a significant effect over the area of the all-sky map. A method for performing image cleaning on likelihood data has also been developed and is used to effectively remove artefacts from the all-sky maps. This paper describes the 'LIMBO' imaging technique and presents preliminary all-sky maps of 25 - 160 keV emission, the first to be made since the HEAO1-A4 mission of 1978-79.
Keywords
Cite
@article{arxiv.astro-ph/0402587,
title = {Gamma-Ray All-Sky Imaging with the Burst and Transient Source Experiment},
author = {S. E. Shaw and M. J. Westmore and A. B. Hill and A. J. Bird and A. J. Dean and C. Ferguson and J. Knödlseder and J. J. Lockley and D. R. Willis},
journal= {arXiv preprint arXiv:astro-ph/0402587},
year = {2009}
}
Comments
16 pages, 10 figures, accepted for publication in Astronomy and Astrophysics. Note: This pre-print contains lower resolution figures than the accepted paper