TITLE: GCN GRB OBSERVATION REPORT NUMBER: 3424 SUBJECT: GRB 050509B and short GRB-SN association? (corrected) DATE: 05/05/15 11:13:06 GMT FROM: Arnon Dar at Technion-Israel Inst. of Tech S. Dado (Technion), A. Dar (Technion) and A. De Rujula (CERN) 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 [4]). While scenarios (a), (b) are not associated with standard optical supernovae (SNe), scenarios (c),(d) are expected to produce a standard optical SN. In particular, in scenario (d), a Type Ia SN is expected at the GRB location with standard rest-frame optical light curves peaking around 20 days after burst with un-reddened absolute magnitudes [5] Bmax ~ -19.47, Vmax ~ - 19.42, Rmax ~ - 19.42 and Imax ~ - 19.06 (+\-0.15). GRB050509B (GCN 3381) is the first well-localized short-duration (~ 30 ms) GRB. A SN associated with a short GRB has never been looked for in such favorable conditions. In the observer's frame the associated-SN expected un-reddened spectral energy density at a frequency nu and a time t after burst is: F(nu,t) = F'(nu',t') [1+z] [D(z')]^2 / ( [1+z'] [D(z)]^2] ) where z' is the redshift of a template Type Ia SN with spectral energy density F'; D(z) and D(z') are luminosity distances, nu'=[(1+z)/(1+z')] nu and t'=[(1+z')/(1+z)] t. If GRB050509B was produced in association with a Type Ia SN in the galaxy cluster NSC J123610+28590, at redshift z = 0.225 (GCN 3390), its rising optical light curve should be observable well before its peak around 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 [6] is included). In spite of the non-detections of an optical afterglow near the refined XRT error circle (GCN 3395) of GRB 050509B, a SN search in this direction, perhaps with telescopes such as Keck, VLT, Subaru and HST, may prove very fruitful. [1] Goodman, J., Dar, A., & Nussinov, S. 1987, ApJ, 314, L7 [2] Hurley, K., et al. 2005, astro-ph/0502329 [3] Dar, A. 1999, A&AS, 138, 505 [4] Dar, A. & De Rujula, A. 2004, Physics Reports, 405, 203 [5] Germany, L. M., et al. 2004, A&A 415, 863 [6] Schlegel, D. J.; Finkbeiner, D. P. & Davis, M. 1998, ApJ, 500, 525