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Fermi LAT Detection of New Gamma-ray Flaring from Gravitationally Lensed Blazar S3 0218+35 and Scheduled Fermi Pointed Observations from 2012 September 24 - October 1

ATel #4411; C. C. Cheung (NRC/NRL), R. Ojha (NASA/GSFC), M. Orienti (Univ. Bologna, INAF-IRA Bologna), D. L. Wood (Praxis/NRL); on behalf of the Fermi Large Area Telescope Collaboration
on 22 Sep 2012; 03:01 UT
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

Subjects: Gamma Ray, >GeV, AGN, Blazar

Recently, the Large Area Telescope (LAT), on board the Fermi Gamma-ray Space Telescope, observed a re-brightening of the gravitationally lensed blazar S3 0218+35, with the source reaching a peak daily flux (E > 100 MeV) of ~2 x 10^-6 ph cm^-2 s^-1 on 2012 September 6. The re-brightening was about ten days after a previous gamma-ray peak (ATel #4343, #4361, #4371), consistent with the time delay of 10.5 +/- 0.4 days measured between the variations in its two compact radio source images (Biggs et al. 1999, MNRAS, 304, 349).

Preliminary analysis indicates the detection of new, brighter gamma-ray flaring activity with peaks on 6-hr timescales of ~4 x 10^-6 ph cm^-2 s^-1 from September 14.5-16.5 and ~6 x 10^-6 ph cm^-2 s^-1 from September 17.25-17.75. Assuming an ~11 day lag, the anticipated delayed flare is expected to begin ~September 25.5. Fermi target-of-opportunity pointed observations are planned to provide increased exposure of S3 0218+35 from September 24.0 to October 1.0.

This source is one of the "LAT Monitored Sources" and consequently a preliminary estimation of the daily gamma-ray flux observed by Fermi LAT is publicly available (link: http://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/ ).

In consideration of this unique observing opportunity, we encourage multi-wavelength observations. For this source the Fermi LAT contact person is Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov).

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.