{
  "bibcode": "2003GCN..2169....1Z",
  "body": "D. Zaritsky (U. Arizona), M. Bolte (UCSC), P. M. Garnavich (Notre\nDame), A. Z. Bonanos and K. Z. Stanek (CfA) report:\n\nSpectra of the optical afterglow of GRB 030329 (Peterson & Price, GCN\n1985; Torii: GCN 1986) and supernova 2003dh (Garnavich et al.  IAUC\n8114) were obtained with the 6.5-m MMT on April 24.15 (UT) and with\nthe Keck-II telescope and ESI spectrograph on April 24.36. Preliminary\nanalysis of the spectra show broad peaks at 560 nm, 450 nm and a sharp\nbreak in the continuum at 390 nm (all in the rest frame).\n\nThe spectrum continues to closely follow the development of SN~1998bw\n(Patat et al. 2001, ApJ, 555, 900). The feature at 450 nm was not\npresent on spectra of SN 2003dh taken April 6 (Matheson et al. GCN\n2107) and suggests a significantly lower photospheric velocity in the\ncurrent spectrum. SN 1998bw developed the 450 nm feature around\nmaximum light and this implies SN 2003dh is now at or past its\nmaximum.\n\nThe continuum of SN 2003dh is bluer than SN 1998bw at a similar phase,\nwhich suggests that the afterglow light still contributes to the total\nflux.\n\nThe April 24 MMT spectrum is available at:\n\nhttp://www.nd.edu/~pgarnavi/grb030329_apr24.jpg\n\nThis message may be cited.",
  "circularId": 2169,
  "createdOn": 1051239452000,
  "email": "kstanek@cfa.harvard.edu",
  "subject": "GRB 030329: Spectral Evolution of SN 2003dh",
  "submitter": "Krzysztof Z. Stanek at CfA  <kstanek@cfa.harvard.edu>",
  "eventId": "GRB 030329"
}