Thursday, March 4, 2010

LAT Limit on Cyg X-1 during reported AGILE flare

Cyg X-1 on Oct. 16th, 2009

Following the announcement by the AGILE team of a high energy transient event from Cyg X-1 during 2009-10-15 UTC 23:13:36 to 2009-10-16 UTC 23:02:24 (ApJ article ; astro-ph) we have checked the LAT data for the same time period. AGILE reported a flux of 23.2 +/- 6.6 E-7 ph/cm2/s in the energy range 100 MeV to 3 GeV during the flare period. A preliminary analysis of the data indicates that the LAT does not detect any significant emission from the location of Cyg X-1 averaged over this time period; the 95% confidence upper limit for the 100 MeV to 3 GeV flux is ~4 e-7 ph/cm2/s assuming a power-law photon index Gamma=2.2.

For questions and comments please contact Adam Hill (adam.hill [at]

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