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GCN Circular 5847

Subject
GRB 061121: MDM Optical Decay
Date
2006-11-23T21:27:58Z (18 years ago)
From
Jules Halpern at Columbia U. <jules@astro.columbia.edu>
J. P. Halpern, N. Mirabal, & E. Armstrong (Columbia U.)
report on behalf of the MDM Observatory GRB follow-up team:

"We observed the afterglow GRB 061121 (Page et al., GCN 5823Not found
 
 
)
in the R band for a second night using the MDM 2.4m telescope.
The following magnitudes from fully reduced images supersede
and extend those reported by us in GCN 5840Not found
 
 
.

 ---------------------------------------------------------
  Date(UT)  Mid-time(UT)  t-t0(hr)  Exp(s)   R(mag)  +/-
 ---------------------------------------------------------
  Nov. 22      11:57       20.57     300     21.10   0.03
  Nov. 22      12:18       20.93     300     21.09   0.03
  Nov. 22      12:26       21.06     300     21.10   0.03
  Nov. 22      12:33       21.18     300     21.11   0.03
  Nov. 22      12:41       21.32     300     21.15   0.03
  Nov. 22      12:49       21.44     300     21.15   0.03

  Nov. 23      11:46       44.39     300     22.08   0.08
  Nov. 23      12:02       44.66     300     21.90   0.06
  Nov. 23      12:08       44.76     300     21.92   0.06
  Nov. 22      12:14       44.86     300     22.02   0.07
  Nov. 23      12:20       44.96     300     21.98   0.07
  Nov. 23      12:28       45.09     300     22.08   0.07
  Nov. 23      12:36       45.23     300     21.99   0.07
  Nov. 23      12:46       45.40     600     22.01   0.05
  Nov. 23      12:57       45.58     600     22.13   0.07
 ---------------------------------------------------------

Magnitudes are referenced to a single USNO-B1.0 star at
(J2000) R.A.=09h48m54.77s, Decl.= -13d11'17.9" with R=18.02.
Quoted uncertainties are statistical only.

The power-law decay index from 21 to 45 hours is -1.08+/-0.03.

Images are posted at http://www.astro.columbia.edu/~jules/grb/061121/

This message may be cited."