OSSE Capabilities for Mapping Diffuse Gamma-Ray Emission
Session 4 -- Gamma Ray Astrophysics
Display presentation, Wednesday, January 12, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [4.02] OSSE Capabilities for Mapping Diffuse Gamma-Ray Emission

M.P.~Ulmer, W.R.~Purcell, D.A.~Grabelsky (Northwestern Univ.), W.N.~Johnson, R.L.~Kinzer, J.D.~Kurfess, M.S.~Strickman (NRL), G.~Jung (USRA), W.A.~Wheaton (JPL)

\def\keV{ke\kern-0.11em V} \def\MeV{Me\kern-0.11em V}

The Oriented Scintillation Spectrometer Experiment (OSSE) onboard NASA's {\it Compton Gamma-Ray Observatory\/} (GRO) was primarily designed to undertake observations of discrete sources and diffuse emission from the Galactic plane. The OSSE instrument is sensitive to gamma-ray line and continuum emission in the 0.05 -- 10 \MeV\ energy range, with collimation of the NaI(Tl) detectors providing a $3.8^\circ \times 11.4^\circ$ full-width at half-maximum field of view. Given the extended nature of the GRO mission, the OSSE instrument provides the ability to perform mapping observations of the Galactic plane as well as the opportunity to perform a partial or complete sky survey. At 100 \keV, these mapping/survey observations would provide about an order of magnitude improvement in sensitivity over previous surveys. Mapping the angular distribution and spectral characteristics of the diffuse Galactic continuum will provide critical information about the morphology and energetics of the cosmic-ray electrons believed to be responsible for the continuum emission. A complete sky survey should provide positive detections, at 100 \keV, of $\sim$ 50 -- 100 previously undetected extragalactic sources. OSSE's capabilities and objectives for performing mapping and survey observations will be presented.