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Fermi LAT detection of a GeV flare from the source 1FGL J1033.8+6048

ATEL # 2622; S. Ciprini (Perugia University and ASI-INAF, Italy), on behalf of the Fermi Large Area Telescope Collaboration
on 16 May 2010; 22:18 UT
Distributed as an Instant Email Notice (Request for Observations)
Password Certification: Stefano Ciprini (

Subjects: Gamma Ray, >GeV, AGN, Quasars, Transients
Referred to by ATEL #: 2623, 2625, 2628, 3062

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increased gamma-ray activity from the Fermi source 1FGL J1033.8+6048 (Abdo et al. 2010, ApJS, accepted, arXiv:1002.2280).  The source became bright and detectable on a daily timescale starting from the end of April. Preliminary analysis points out that on 14th May 2010, it reached a daily integrated gamma-ray flux (E>100MeV) of (1.5+/-0.3)x10^-6 ph cm-2 s-1, and a 6h integrated flux on the third quarter of that day of (2.5+/-0.8)x10^-6 ph cm-2 s-1 (statistical uncertainty only). This is the first time that Fermi is reporting flaring activity from this gamma-ray source, which has two potential flat spectrum radio quasar associations.

1FGL J1033.8+6048 is associated to S4 1030+61 (also known as TXS 1030+611,  GB6 J1033+6051,  RA, Dec: 158.46429 deg, 60.85203 deg,  J2000.0, by Beasley et al. 2002, ApJS, 141, 13) an object with redshift  z=1.4009 (by SDSS3 and SDSS4, Schneider et al. 2005, AJ, 130, 367). A value z=0.336 was reported previously by Stickel & Kuehr 1994, A&AS, 103, 349.

1FGL J1033.8+6048  is also associated to GB6 J1032+6051 (also known as 87GB 102932.2+610651, RA, Dec: 158.22483 deg, 60.85767 deg,  J2000.0 by SDSS6, Adelman-McCarthy et al. 2008, ApJS, 175, 297),  an object with redshift z=1.064 (Abdo et al. 2010, ApJ, 715, 429).

Using about 21 months of accumulated LAT data (2008 August 04 - 2010 April 30) the gamma-ray source is localized to RA, Dec = 158.483 deg, 60.844 deg, J2000.0, with 95% confinement radius r95 =  0.05 deg, a position consistent with S4 1030+61. Using only the data of May 14th, the source is localized to RA, Dec: 158.292 deg, 60.822 deg, r95 = 0.12 deg, closer to GB6 J1032+60511.

In consideration of the ongoing activity of this gamma-ray source, and the ambiguity of the counterpart association, we strongly encourage multiwavelength observations. Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. The Fermi LAT contact persons for this source are E. Wallace (eewallace[at] and S. Ciprini (stefano.ciprini[at]

The Fermi LAT is a pair conversion telescope designed to cover the energy band 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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R. E. Rutledge , Editor
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