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Fermi-LAT detection of renewed activity from the blazar PKS 1502+106

ATEL # 1905; D. Horan (LLR), E. Hays (NASA/GSFC) on behalf of the Fermi Large Area Telescope Collaboration
on 22 Jan 2009; 22:59 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Elizabeth Hays (

Subjects: Gamma Ray, >GeV, Request for Observations, AGN, Quasars

The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope (formerly GLAST, launched June 11, 2008), has observed, on 21 January 2009, an increased gamma-ray flux from a source positionally consistent with the blazar PKS 1502+106 (R.A.:15h04m24.9797s; Dec.:+10d29m39.198s, z=1.83, also known as OR 103 and S3 1502+10).

Preliminary analysis indicates that the source was in a high state on 21 January 2009 with a gamma-ray flux (E>100MeV) of 1.8 +/- 0.3 x10^-6 photons cm^-2 s^-1, which represents an increase of a factor of approximately 2 with respect to its recent flux level. This is the second time that Fermi is observing and announcing a relevant GeV flare from this blazar, which had not been detected in the gamma-ray regime prior to the initial Fermi detection (August 2008, ATEL#1650). These observations indicate that this source flares on sub-day time scales. PKS 1502+106 was already the target of the first Fermi multifrequency campaign in August 2008.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. In consideration of the ongoing activity of this source we strongly encourage multiwavelength observations. For this source the Fermi LAT contact person is S. Ciprini (

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.

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