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GCN Circular 3399

GRB 050509b: Physical Properties of the Candidate Host galaxy
2005-05-10T00:53:14Z (19 years ago)
Hsiao-Wen Chen at MIT/CSR <>
Jason X. Prochaska (UCO/Lick Obs.), J. S. Bloom (UCB), H.-W. Chen (MIT), & 
K. Hurley (UCB) report on behalf of the GRAASP collaboration:

"We have further analyzed the longslit spectrum obtained for the candidate host
galaxy of GRB 050509b Bloom et al. GCN 3386) by Prochaska et al. (GCN 3390),
using Keck/DEIMOS.  We estimate a more precise redshift of the galaxy at z = 
0.2249 +/- 0.0008 by cross-correlating the spectrum with galaxy templates from
SDSS.  At this redshift, the host has an intrinsic K-band luminosity of 
~ 1.6 x 10^11 L_sun as derived based on its 2MASS photometry of K = 14.1 mag.
We attempt to constrain the underlying dark matter halo mass of the galaxy 
based on the observed absorption line profiles.  Using the Ca H&K doublet, we 
estimate a velocity dispersion of ~ 340 km/sec.  This corresponds to an 
enclosed dynamical mass of 7.2 x 10^11 h^{-1} M_sun at the radius of the 
OT r = 26.6 h^-1 kpc.  The spectrum of the galaxy is presented at

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