J. Rodi, M. L. Cherry, G. L. Case, A. Camero-Arranz, C. Chaplin, M. H. Finger, P. Jenke, C. A. Wilson-Hodge
The Earth Occultation Technique (EOT) has been applied to Fermi's Gamma-ray Burst Monitor (GBM) to perform all-sky monitoring for a predetermined catalog of hard X-ray/soft gamma-ray sources. Imaging with a Differential filter using the Earth Occultation Method (IDEOM) has been developed to search for sources not in the catalog, thus completing the catalog and reducing a source of systematic error in EOT. IDEOM is a tomographic imaging method that takes advantage of the orbital precession of the Fermi satellite. Using IDEOM, all-sky images have been generated for ~4 years of GBM data in the 12-50 keV, 50-100 keV and 100-300 keV energy bands in search of sources otherwise unmodeled by the GBM occultation analysis. Analysis resulted in the detection of 43 sources in the 12-50 keV energy band, 23 sources in the 50-100 keV energy band, and 7 sources in the 100-300 keV energy band. IDEOM analysis has resulted in the addition of 16 sources to the GBM-EOT catalog. We also present the first joined averaged spectra for four persistent sources detected by GBM using EOT and by the Large Area Telescope (LAT) on Fermi: NGC 1275, 3C 273, Cen A, and the Crab.
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http://arxiv.org/abs/1304.1478
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