{
  "bibcode": "2003GCN..2117....1E",
  "body": "Mike Eracleous (Penn State), Brad Schaefer, and Chris Gerardy\n(U. Texas) on behalf of the Hobby-Eberly Telescope GRB followup team\nreport:\n\nWe have obtained several spectra (410-900 nm, resolution 1.6 nm) of\nthe optical counterpart of GRB030329 (Peterson & Price, GCN 1985;\nTorii: GCN 1986) with the Hobby-Eberly Telescope and Marcario\nLow-Resolution spectrograph. Our spectra of March 31, April 2, and\nApril 5 (UT) show the following evolution of the spectral properties:\n(a) the equivalent widths of the [O III] and H-alpha emission lines is\nincreasing in a manner consistent with a constant line flux and a\ndecline of the continuum, and (b) the spectrum of April 5 (UT) shows\nevidence of a broad feature underlying the [O III] lines, similar\ntresembling that reported by Matheson et al. (GCN 2107), who interpret\nit as due to an emerging SN spectrum. However, the contrast of this\nfeature in our spectrum is not as high as in the spectrum of Matheson\net al. (taken a day later than ours). As a consequence, we cannot rule\nout alternative interpretations, such as the emergence of a host\ngalaxy spectrum that manifests itself as a break in the power-law\ncontinuum.  Analysis of more recent spectra is under way to clarify\nthis issue.\n\nUsing the [O II] and H-alpha emission line fluxes of Caldwell et\nal. (GCN 2053), we estimate luminosities of 1x10^40 and 4x10^40 erg/s,\nrespectively (for z=0.168, i.e., a luminosity distance of 880 Mpc),\nand infer star formation rates of 0.15 and 0.32 solar masses/yr\n(following Kennicutt 1998, ARAA, 36, 189). The upper limit on the host\ngalaxy from historical images reported by Wood-Vasey et al.  (GCN\n1998; R > 22.28) implies a limit on the absolute magnitude of M_R >\n-17.4, which is comparable to that of the LMC. The [OIII]/H-beta ratio\nof 2.7 (Caldwell et al.; GCN 2053) corresponds to an LMC-like faint\nstarburst galaxy (Ho, et al. 1997, ApJ, 487, 579, Figure 6; Hunter &\nGallagher, 1997, ApJ, 475, 65; Hunter et al. 2001 ApJ, 553, 121),\nwhile the H-alpha luminosity is characteristic of starburst galaxies\n(Ho. et al. Figure 2). High-dispersion spectroscopy of these narrow\nlines may give more information on the nature of star formation in the\nhost galaxy.",
  "circularId": 2117,
  "createdOn": 1049773024000,
  "email": "mce@astro.psu.edu",
  "subject": "GRB030329: HET spectroscopic monitoring",
  "submitter": "Mike Eracleous at PSU, Astro.Dept.  <mce@astro.psu.edu>",
  "eventId": "GRB 030329"
}