Fermi-LAT Gamma-ray Observations of Nova Sagittarii 2015 No. 2

ATel #7283; C. C. Cheung (NRL), P. Jean (IRAP, Toulouse), on behalf of the Fermi Large Area Telescope Collaboration, S. N. Shore (U. Pisa and INFN)
on 24 Mar 2015; 19:01 UT
Distributed as an Instant Email Notice Novae
Credential Certification: Teddy Cheung (ccheung@milkyway.gsfc.nasa.gov)

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The Fermi Gamma-ray Space Telescope began a Target of Opportunity (ToO) observation of the classical nova, Nova Sgr 2015 No. 2 (CBET 4080) commencing around March 17.9, about 2 days after optical discovery. Preliminary analysis of Large Area Telescope (LAT) data from March 23.00-24.24 showed evidence for >100 MeV emission from the nova at 3.8 sigma significance, with an average flux, F(E>100 MeV) = (1.4 +/- 0.6) x 10^-7 ph cm^-2 s^-1 (assuming a single power-law with photon index = 2.2 fixed in the fit). Detectable gamma-ray emission was found ~1.5 days after the optical emission peaked around March 21.5 (pre-validated AAVSO lightcurve), similar to the cases of V339 Del 2013 (ATEL #5302; Fermi-LAT collaboration, 2014 Science, 345, 554) and V1369 Cen 2013 (ATEL #5649).

We strongly encourage multiwavelength observations. The Fermi ToO observation of Nova Sgr 2015 No. 2 will continue until March 29.0. For this source the Fermi LAT contact person is C.C. Cheung (Teddy.Cheung@nrl.navy.mil).

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.