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GCN Circular 2053

Subject
GRB 030329, optical spectroscopy
Date
2003-04-01T00:30:50Z (21 years ago)
From
Peter Garnavich at U of Notre Dame <pgarnavi@miranda.phys.nd.edu>
N. Caldwell (CfA), P. Garnavich, S. Holland (Notre Dame),
  T. Matheson and K.Z. Stanek (CfA)

Spectra of the optical afterglow of GRB 030329 (Peterson & Price,
GCN 1985; Torii: GCN 1986) were obtained with the
6.5-m MMT and Blue-Channel spectrograph on March 30 and 31 (UT)
The low-resolution spectra cover the wavelength
range of 3500 to 8500 Ang. with a resolution of 7 Ang. FWHM.
Analysis of the spectrum taken in good seeing on March 31
shows several narrow emission lines. The line seen at
5852 Ang. by Martini et al. (GCN 2013) and Della Ceca et al.
(GCN 2015) is, in fact, [OIII] 5007 and confirms the redshift
estimate of Greiner et al. (GCN 2020) of z=0.168.

In a 1.25" wide slit we find the following observed fluxes:

 observed      ID        z     Flux (10^-16 erg/cm^2/s)
  7669.2  Halpha 6563  0.1686       4.5
  5851.1  [OIII] 5007  0.1686       4.1  
  5795.4  [OIII] 4959  0.1687       1.6
  5681.7  Hbeta  4861  0.1687       1.5
  4356.1  [OII]  3727  0.1687       1.2

A narrow absorption line is detected at 3933.2 Ang. 
with an equivalent width of 0.4 Ang. and is probably
due to CaII in our Galaxy.

An estimate of the star formation rate in the 4 kpc
of the host galaxy nearest the burst can be made
from the [OII] luminosity (Kennicutt 1998, ARAA, 36, 189;
assuming H0=72).  The rate is an anemic ~0.1 Solar masses/yr.
without correcting for host extinction. The Halpha/Hbeta
ratio is not well determined from these data, but does not
imply a large extinction. We therefore conclude that the
SFR of the GRB 030329 host is very low.


This message may be cited.

[GCN OPS NOTE(02apr03): The SFR was corrected from "... an anemic ~0.01 ..."
to "... an anemic ~0.1 ...".]
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