[AAVSO-HEN] GRB 080906: Refined Swift/UVOT Photometric Redshift

[grb at aavso.org]

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TITLE:   GCN CIRCULAR
NUMBER:  8212
SUBJECT: GRB 080906: Refined Swift/UVOT Photometric Redshift
DATE:    08/09/11 14:38:23 GMT
FROM:    Stephen Holland at USRA/NASA/GSFC/SSC  <Stephen.T.Holland at nasa.gov>

Stephen Holland (CRESST/USRA/GSFC) reports, on behalf of the
Swift/UVOT team:

      We have performed UVOT photometry on the optical afterglow of GRB
080906 (Vetere et al., 2008, GCNC 8186) at approximately 6000 s after
the BAT trigger.  This data was used to estimate the photometric
redshift of the afterglow assuming a reddened power-law spectrum with
a Lyman cut-off.  We find a best-fit value for the photometric
redshift of z = 2.0 +/- 0.4 (90% confidence).  Combining this redshift
with the BAT fluence given in Stamatikos et al. (2008, GCNC 8196)
yields a total energy of (8.4 +/- 0.5) x 10^51 erg (90% confidence) in
the observed energy range 15-150 keV.  The assumed cosmology is
(H_0,Omega_matter,Omega_lambda) = (70,0.3,0.7).