Data Centre for Astrophysics
Astronomy Department of the University of Geneva
ISDC Seminar

Friday, October 11, 2002 at 11:00

Simon Shaw
ISDC, Geneva

Imaging the Gamma Ray Sky with BATSE

Abstract. The Burst and Transient Source Experiment (BATSE) was one of the instruments on board the Compton Gamma Ray Observaotory (CGRO), which operated in a low Earth orbit for ~ 9 years from 1991 - 2000. BATSE was designed with a 4$\pi$ field of view with the primary aim of detecting as many gamma ray bursts as possible above 20 keV. More persisitent sources of gamma rays can be observed using the Earth Occultation Technique where images of the Earth's limb, caused by gamma ray sources rising above or setting below the horizon, can be projected on to the sky to build up an image. To fully use the long 9 year exposure of BATSE it is necessary to produce an accurate background model. The BATSE Mass Model uses a Monte Carlo technique, based on the INTEGRAL Mass Model (TIMM) produced at Southampton, and is capable of accurately reproducing the observed background in all of the 16 BATSE energy channels every 2 seconds for the entire mission. The background modelling and imaging techniques have allowed the production of the first all sky images in the 20 - 100 keV band to be seen since the HEAO-1 A4 mission of 1978-79. When all the data is considered the final survey should have a sensitivity of ~ 1 mCrab and angular resolution < 1 degree.

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