All-Sky Earth Occultation Observations with the Fermi Gamma Ray Burst Monitor

TL;DR

This paper discusses the use of Fermi's GBM instrument to monitor the sky through Earth occultation, detecting various astrophysical sources and solar panel occultations, providing a new all-sky observation method in hard X-ray and soft gamma-ray energies.

Contribution

It introduces a novel application of the Fermi GBM for all-sky monitoring via Earth occultation, expanding observational capabilities beyond traditional methods.

Findings

Detection of galactic X-ray binaries, Crab Nebula, and AGN.

Observation of solar panel occultations.

Preliminary catalog and early results presented.

Abstract

Using the Gamma Ray Burst Monitor (GBM) on-board Fermi, we are monitoring the hard X-ray/soft gamma ray sky using the Earth occultation technique. Each time a source in our catalog enters or exits occultation by the Earth, we measure its flux using the change in count rates due to the occultation. Currently we are using CTIME data with 8 energy channels spanning 8 keV to 1 MeV for the GBM NaI detectors and spanning 150 keV to 40 MeV for the GBM BGO detectors. Our preliminary catalog consists of galactic X-ray binaries, the Crab Nebula, and active galactic nuclei. In addition, to Earth occultations, we have observed numerous occultations with Fermi's solar panels. We will present early results. Regularly updated results can be found on our website http://gammaray.nsstc.nasa.gov/gbm/science/occultation