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The region around SGR 1806-20 and its host stellar cluster Cl* 1806-20 is apotentially important site of particle acceleration. The soft $\gamma-$rayrepeater and Cl* 1806-20, which also contains several very massive starsincluding a luminous blue variable hypergiant LBV 1806-20, are capable ofdepositing a large amount of energy to the surroundings. Using the data takenwith the \emph{Fermi} Large Area Telescope (LAT), we identified an extended LATsource to the south-west of Cl* 1806-20. The centroid of the 1-50~GeV emissionis consistent with that of HESS J1808-204 (until now unidentified). The LATspectrum is best-fit by a broken power-law with the break energy$E_\mathrm{b}=297\pm15$ MeV. The index above $E_\mathrm{b}$ is $2.60\pm0.04$,and is consistent with the flux and spectral index above 100 GeV for HESSJ1808-204, suggesting an association between the two sources. Meanwhile, theinteracting supernova remnant SNR G9.7-0.0 is also a potential contributor tothe LAT flux. A tentative flux enhancement at the MeV band during a 45-dayinterval (2011 Jan 21 - 2011 Mar 7) is also reported. We discuss possibleorigins of the extended LAT source in the context of both leptonic and hadronicscenarios.

Studying the SGR 1806-20/Cl* 1806-20 region using the \emph{Fermi} Large Area Telescope