{
  "bibcode": "2003GCN..2081....1Z",
  "body": "A. Zeh, S. Klose (Thueringer Landessternwarte Tautenburg),\nJ. Greiner (MPE Garching),\n\nreport:\n\n\nUsing the light curves of SN 1998bw (Galama et al. 1998, Nature 395,\n670) as a template we have analyzed what color changes are expected to\nbe seen in the optical transient following GRB 030329 if a supernova\ncomponent would appear.\n\n\nIngredients:\n------------\n\n1) SN 1998bw:\n\n- A_V = 0.20 mag (Woosley, Eastman, & Schmidt 1999, ApJ 516, 792)\n- no time delay between the onset of the SN and the onset of the GRB\n- A_V(host) = 0.0 mag\n\n\n2) The host galaxy:\n\n- z = 0.1685 (Greiner et al. 2003, GCN 2020)\n- a negligible host flux in BVRI (based on R>22.5; Blake & Bloom 2003,\n  GCN 2011)\n- A_V(Galaxy) at (l, b) = 217.07, b = 60.68:\n  E(B-V) = 0.025 (Schlegel, Finkbeiner, & Davis 1998, ApJ 500, 525),\n- R_V = 3.1\n\n\n3) The GRB afterglow:\n\n- Considering published GCN R-band data, analyzed according to\n  Beuermann et al. (1999, A&A 352, L26), we find:\n\n  alpha_1 = 0.85 +/- 0.04\n  alpha_2 = 1.55 +/- 0.02\n  t_break = 0.42 +/- 0.03 days,\n\n  after ignoring the several re-brightenings during the last days\n\n- colors (best fit):\n  B-V = 0.39 mag\n  V-R = 0.34 mag\n  R-I = 0.47 mag\n\n- we have taken into account the latest re-brightening episode and assumed that\n  a) alpha_2 remains constant and b) the color of the afterglow does not change\n\n\nOutput cocktail:\n----------------\n\n - Fig. 1: the light curve\n - Fig. 2: the expected color evolution\n\nWe note that differences in the reported value for alpha_2 (cf. Li\net al. 2003, GCN 2078) can be explained by slightly different\nselection criteria for the data chosen to perform the numerical fit.\n\nhttp://www.tls-tautenburg.de/research/klose/grb.html\n\n\nWarning:\n--------\n\nThese results are based on a simple toy model. They provide only a\nhint about what the strength of the SN signal could be since most\nSN bumps found so far had a brightness of only 30-80% of SN 1998bw.",
  "circularId": 2081,
  "createdOn": 1049379056000,
  "email": "klose@tls-tautenburg.de",
  "subject": "GRB 030329, light curve and SN prediction",
  "submitter": "Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>",
  "eventId": "GRB 030329"
}