[vsnet-grb-info 4137] GRB 061201: Magellan Redshift of nearby Abell cluster

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  5944
SUBJECT: GRB 061201: Magellan Redshift of nearby Abell cluster 
DATE:    06/12/20 07:42:22 GMT
FROM:    Josh Bloom at UC Berkeley  <jbloom at astron.berkeley.edu>

S. Blondin, G. Narayan (Harvard/CfA),  J. S. Bloom (UC Berkeley), H- 
W. Chen (U Chicago), R. P. Kirshner, P. Challis,  M. Hicken, M.  
Modjaz, A. Friedman, M. Wood-Vasey (Harvard/CfA), and J. X. Prochaska  
(UC Santa Cruz) report on behalf of a larger collaboration:

"The final X-ray afterglow position (Perri et al. 2006; GCN 5885) of  
the short-hard GRB 061201 (Marshall et al. 2006; GCN 5881) lies 8.5  
arcmin from the center of the rich Abell cluster 995 (Bloom 2006; GCN  
5880). On 13 December 2006 UT, we obtained several spectra of bright  
apparent cluster members with the LDSS-3 instrument mounted on the  
Magellan Clay 6.5m Telescope in Chile. We find the following  
redshifts based upon a preliminary inspection of the spectra:

    				     RA (J2000)          DEC(J2000)
				===========================
      object A: z=0.239      22:08:32.1              -74:34:47
      object B: z=0.235      22:09:37.1              -74:26:39
      object D: z=0.238      22:09:05.3              -74:29:29

Based on this, we claim a redshift of z=~0.237 for Abell 995 and note  
that while the GRB is not yet definitively associated with a cluster  
member galaxy, this redshift (and hence the implied energetics of the  
event) are very similar to the putative redshifts of short-hard GRBs  
050509b (z=0.225), 050724 (z=0.258), and 060502b (z=0.287)."

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