TITLE: GCN CIRCULAR NUMBER: 14260 SUBJECT: GRB 130305A: Fermi LAT Detection DATE: 13/03/05 22:54:38 GMT FROM: Sylvain Guiriec at UAH S. Guiriec (NASA/GSFC/NPP), J. L. Racusin (NASA/GSFC), G. Vianello (Stanford) and D. Kocevski (NASA/GSFC/NPP) report on behalf of the Fermi-LAT team: The Fermi Large Area Telescope (LAT) detected emission from GRB 130305A at approximately 11:39:11 UT on March 5th, 2013, while in Target Of Opportunity (i.e., pointing) mode observing the Crab (ATEL #4855). GRB 130305A was detected by Fermi-GBM (GBM trigger 130305486/384176354) and Swift-BAT (Cummings et al., GCN #14257). The burst location was within the LAT field of view at an angle of ~41 degrees to the LAT boresight, and ~100 degrees from the zenith, placing it very close to the Earth's limb, which is a very bright source of gamma rays. No significant excess is seen using standard analysis procedures (>100 MeV) neither in the prompt phase nor in a search for extended emission when the burst position was no longer occulted from ~1500 to 5000 s. Using the non-standard LAT Low Energy (LLE) data selection, >550 counts above background were detected in a single FRED like pulse, peaking between 5 and 10 s after the GBM trigger and coinciding with the time of the GBM emission, with a significance of ~10.7 sigma. This detection is due to low energy gamma-rays, below 75 MeV, and therefore has insufficient spatial resolution to provide a reliable LAT localization. A GBM circular on GRB 130305A is forthcoming. The Fermi LAT point of contact for this burst is Sylvain Guiriec (sylvain.guiriec@nasa.gov)