TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3423 SUBJECT: GRB 050509B and short GRB-SN association? DATE: 05/05/15 08:56:20 GMT FROM: Arnon Dar at Technion-Israel Inst. of Tech S. Dado (Technion) and A. Dar (Technion) report: The leading scenarios for the production of short-duration GRBs involve (a) neutron-star mergers [1] (b) super flares from SGRs (GCN 2942 and [2]) (c) gravitational collapse of neutron-stars to strange-quark stars [3] (d) gravitational collapse of C/O white dwarfs to neutron stars (GCN 2174) and [3]). While scenarios (a),(b) are not associated with standard optical SNe, scenarios (c),(d) are expected to produce a standard optical SN. In particular, in scenario (d), a bright SNIa is expected at the GRB location with a standard rest frame optical light curves which peak around 20 days after burst with un-reddened absolute rest frame magnitudes, Bmax~-19.47, Vmax~-19.42, Rmax~-19.42 and Imax~-19.06 (+\-0.15 magnitude). GRB050509B (GCN 3381) is the first well localized short-duration (~30 ms) GRB. It allows a late time search of an SN associated with a short duration GRB. In the observer frame the expected un-reddened spectral energy density at a frequency nu and a time t after burst is: F(nu,t)=((1+z) [D_L(z')]^2 / (1+z')[D_L(z)]^2) Ftsn(nu',t') where z' is the redshift of the template SNIa whose spectral energy density is Ftsn and nu'=[(1+z)/(1+z')] nu, t'=[(1+z')/(1+z)] t. If GRB050509B was produced in an SNIa in the galaxy cluster NSC J123610+285901 at a redshift z~0.225 (GCN 3390), its observed V-band light curve should peak near t=25 days after burst with Vmax~20.43+/- 0.15 (extinction in the host galaxy is not included, but Galactic extinction in the direction of GRB 050509B, Av~0.06 [5] is included). Despite the failures so far to detect an optical afterglow within/near the refined XRT error circle (GCN 3395) of GRB 050509B, an SN search within/near the burst XRT error circle, with the most powerful telescopes such as Keck, VLT, Subaru and HST, is highly encouraged. [1] Goodman, J, Dar, A, & Nussinov, S. 1987, ApJ, 314, L7 [2] Hurley, K., et al. 2005, astro-ph/0502329 [2] Dar, A. 1999, A&AS, 138, 505 [3] Dar, A. & De Rujula, A. 2004, Physics Reports, 405, 203 [4] Germany, L. M., et al. 2004, A&A 415, 863 [5] Schlegel, D. J.; Finkbeiner, D. P. & Davis, M. 1998, ApJ, 500, 525