TITLE: GCN CIRCULAR NUMBER: 35271 SUBJECT: Fermi-LAT daily aperture light curve of T CrB now available DATE: 23/12/05 18:52:43 GMT FROM: C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil> C. C. Cheung (NRL), T. J. Johnson (GMU, resident at NRL), P. Jean (IRAP, Toulouse), G. Marti-Devesa (Univ. of Innsbruck), on behalf of the Fermi Large Area Telescope Collaboration: T Coronae Borealis (T CrB) is a known recurrent nova with the next, long-anticipated explosion expected in early 2024. The 2024 nova eruption prediction is based on the approximately 80-year recurrence between prior outbursts and the recent detection of the start of a pre-eruption dip (in March/April 2023; ATel #16107), which may indicate a change in the accretion state (e.g., Luna et al. 2020, ApJL, 902, L14). This dip was also observed prior to its last outburst in 1946. Because of its proximity (distance ~0.9 kpc; Schaefer 2022, MNRAS, 517, 6150), T CrB is expected to be detected brightly as a gamma-ray transient with a peak (E >100 MeV) flux of ~(1-2) x 10^-5 photons cm^-2 s^-1 if it is similar to other known recurrent symbiotic novae detected by Fermi-LAT (e.g., V407 Cyg; Ackermann et al. 2014, Sci, 345, 554; RS Oph 2021; Cheung et al. 2022, ApJ, 935, 44). In consideration of its expected bright outburst in gamma rays, a preliminary Fermi-LAT aperture light curve (daily and weekly bins) is updated daily and publicly available at: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/msl_lc/source/T_CrB . For this source the Fermi LAT contact 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. Note: the text of this notice was also posted as: https://www.astronomerstelegram.org/?read=16336 View this GCN Circular online at https://gcn.nasa.gov/circulars/35271. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...