Fermi-LAT Gamma-ray Detection of the Nova V7994 Sgr
ATel #17419; G. Marti-Devesa (University and INFN Trieste), Paul Fauverge (University of Bordeaux and CNRS), Pierre Jean (IRAP, Toulouse), C. C. Cheung (NRL) on behalf of the Fermi Large Area Telescope Collaboration
on 25 Sep 2025; 21:25 UT
Credential Certification: Guillem Marti-Devesa (guillem.marti-devesa@ts.infn.it)
Subjects: Gamma Ray, >GeV, Nova, Transient
The Large Area Telescope (LAT), one of two instruments on the Fermi Gamma-ray Space Telescope, has detected gamma-ray emission from a source positionally consistent with V7994 Sgr (TCP J18035290-3127298), discovered by J. Seach on 2025 Sep 21.381 UT at 10.2 mag (CBET #5612).
Preliminary analysis of LAT data from 2025-09-23 14:33 to 2025-09-25 04:15 results in a >5-sigma significance detection with a (E >100 MeV) flux of (3.5 +/- 1.3) x 10^-7 photons cm^-2 s^-1 and a photon index = 1.9 +/- 0.2 (statistical uncertainties only). The highest-energy photon, with an energy of 12.9 GeV and an association probability of 99.8%, was recorded on 2025-09-23 at 20:04:51. The new source does not correspond to a previously known source or to a plausible extragalactic counterpart, but is consistent with the optical position of the nova (R.A. = 18h03m52s.90 deg, Dec. = -31d27'29".8 deg, J2000).
Because Fermi normally 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 encourage multi-wavelength observations. 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.
