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Fermi and Swift observations of the new unidentified gamma-ray point source Fermi J1418+3541

ATel #4643; Michael Dutka (Catholic U.), Roopesh Ojha (NASA/GSFC), Yasuyuki Tanaka (Hiroshima University) and Kirill Sokolovsky (ASC Lebedev/SAI MSU) on behalf of the Fermi LAT Collaboration
on 12 Dec 2012; 12:38 UT
Credential Certification: Roopesh Ojha (Roopesh.Ojha@gmail.com)

Subjects: Optical, Ultra-Violet, X-ray, Gamma Ray, >GeV, AGN, Blazar, Quasar

Referred to by ATel #: 4645, 4750, 5202

The Large Area Telescope (LAT), one of the two instruments on the Fermi Gamma-ray Space Telescope, has observed increasing gamma-ray flux from an unidentified source whose preliminary location is RA: 214.63 DEC: 35.69 (14:18:31 +35:41:23, J2000), with an error circle of 0.07 degrees (4.2') radius, with 95% confidence level. The daily averaged gamma ray flux peaked at a flux of (0.5+/-0.2) e-6 ph/cm^2/sec in the 100 MeV - 300 GeV energy range on November 20, 2012. Its photon index evolved from 1.5+/-0.3 on November 17, 2012 to 2.1+/-0.3 on November 20, 2012.

Swift follow up observations centered on this position were made for 5 ks on November 21, 2012. The UVOT data show that the source NVSS J141828+354250 is within the LAT error circle and significantly brighter than historical magnitudes. The UVOT results are:
U = 17.38+/-0.08
W1 = 17.48+/-0.07
W2 = 17.65+/-0.05
M2 = 17.55+/-0.06
where the errors are 1-sigma and the units are in UVOT Vega system.

A historical photometric measurement of this source from the Sloan Digital Sky Survey shows a U Vega magnitude of 19.24. Further multi-wavelength observations will allow us to confirm this identification. A preliminary analysis of the XRT data on NVSS J141828+354250 in the 0.3-10 keV range shows a steep X-ray spectrum (photon index = 2.6 +0.8/-0.6). Note the large error in the photon index. NVSS J141828+354250 is not detected as an X-ray source in any all sky X-ray survey. We thank the Swift team for their rapid scheduling of these observations.

Because Fermi operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. Multiwavelength observations during the ongoing activity of this source are strongly encouraged. The Fermi LAT contact person is Michael Dutka (e-mail: ditko86@gmail.com).

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.