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Fermi LAT detection of enhanced gamma-ray activity from the Sun on June 7 2011

ATel #3417; Y. T. Tanaka (ISAS/JAXA), N. Omodei (Stanford University), H. Takahashi (Hiroshima Univ.), E. Grove (NRL), S. Ciprini (ASDC-INAF) on behalf of Fermi/LAT collaboration
on 9 Jun 2011; 02:16 UT
Credential Certification: Yasuyuki T. Tanaka (tanaka@astro.isas.jaxa.jp)

Subjects: Gamma Ray, >GeV, The Sun

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, detected an increasing gamma-ray flux from a source at R.A.=74.9 deg, Dec.=22.5 deg, positionally consistent with the Sun (R.A. 74.9 deg, Dec. 22.7 deg, J2000).

Preliminary analysis indicates that the Sun was detected in a six-hour period (6-12 UT) on 7 June, 2011 with a gamma-ray flux (E>100 MeV) reaching (4.5+/-0.5)x 10^-5 photons cm^-2 s^-1 (statistical error only). Since the gamma-ray flux of the solar disk for the quiet Sun is (4.6+/-0.2)x 10^-7 photons cm^-2 s^-1(Abdo et al. ApJ, 734, 116, 2011), the flux increased by about two orders of magnitude. In the next six-hour period (12-18 UT), however, the Sun was not detected.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of the Sun will continue. For this detection, the Fermi LAT contact person is Yasuyuki Tanaka (tanaka@astro.isas.jaxa.jp).

The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.