All-sky monitoring of variable sources with Fermi GBM

Document Type

Conference Proceeding

Publication Date



Using the Gamma ray Burst Monitor (GBM) on Fermi, we monitor the transient hard X-ray/soft gamma ray sky. The twelve GBM NaI detectors span 8 keV to 1 MeV, while the two BGO detectors span 150 keV to 40 MeV. We use the Earth occultation technique to monitor a number of sources, including X-ray binaries, AGN, and solar flaring activity. Our monitoring reveals predictable and unpredictable phenomena such as transient outbursts and state changes. With GBM we also track the pulsed flux and spin frequency of accretion powered pulsars using epoch-folding techniques. Highlights from the Earth Occultation and Pulsar projects will be presented including our recent surprising discovery of variations in the total flux from the Crab. Searches for quasi-periodic oscillations and X-ray bursts are also possible with GBM all-sky monitoring capabilities. With these results we show how crucial an all-sky monitor is for any future X-ray timing mission.

Publication Source (Journal or Book title)

Proceedings of Science

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