Fermi-LAT Gamma-ray Observations of the Classical Nova V6598 Sgr 2023
ATel #16151; P. Jean (IRAP, Toulouse), T. J. Johnson (GMU, resident at NRL), C. C. Cheung (NRL), on behalf of the Fermi Large Area Telescope Collaboration
on 25 Jul 2023; 22:24 UT
Credential Certification: Teddy Cheung (Teddy.Cheung@nrl.navy.mil)
Subjects: Gamma Ray, >GeV, Nova, Transient
We report Fermi Gamma-ray Space Telescope observations of the classical nova V6598 Sgr 2023 discovered independently by A. Pearce and Y. Nakamura on July 15.459 and 15.522, respectively (CBET 5278). Preliminary analysis of the Large Area Telescope (LAT) data from 2023 July 13.0 to 21.0 on daily intervals indicated low-level gamma-ray emission at the optical position (Gaia DR3, J2000; R.A. = 17 52 49.31, Decl. = -20 24 15.4) on the day spanning the optical discovery and the following 1-day interval. Fitting the 2-day LAT dataset from July 15.0-17.0 with a single power-law spectrum, we find a ~4-sigma significance for a source with an average flux, F(E>100 MeV) = (1.9 +/- 1.2) x 10^-7 ph cm^-2 s^-1 and a photon index of 1.7 +/- 0.3 (statistical errors only). The best-fit LAT position (J2000) is R.A. = 268.39 deg, Decl. = -20.50 deg with a 95% confidence error radius of 0.20 deg, thus consistent with the optical position.
Because Fermi normally operates in an all-sky scanning mode, regular gamma-ray monitoring of this source will continue. We encourage multi-wavelength observations. For this source the Fermi LAT contact people are P. Jean (pjean@irap.omp.eu) and 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.
