[AAVSO-HEN] GRB 041006: BR observations with VATT

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TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  2792
SUBJECT: GRB 041006: BR observations with VATT
DATE:    04/10/09 03:29:13 GMT
FROM:    Krzysztof Z. Stanek at CfA  <kstanek at cfa.harvard.edu>

P. Garnavich, X. Zhao, T. Pimenova (Notre Dame)

We observed the field of the afterglow of GRB 041006 reported by Noel & Price
(GCN 2765) with the 1.8-m Vatican Advanced Technology Telescope (VATT) beginning
on Oct. 8.251 (UT) (2.25 days after the burst). Exposures totaling 25 minutes
in R and B were obtained in 1" seeing. Standard stars were also observed
and color terms applied to two local standards:

          RA  (J2000)   Dec                R            B
Star A  00:54:47.044 +01:14:05.61     17.71 (04)    18.24 (04)
Star B  00:54:54.494 +01:15:47.81     16.28 (04)    17.95 (04)

showing that the USNO A2.0 red magnitudes are 0.4 mag too bright for this
field as noted by Fugazza et al. (GCN 2782) and that the B-mags are way
off.

The optical transient is measured to be R=22.31 (05) and
B=23.09 (06) mag. The reddening in this direction (Schlegel et al. 1998)
is E(B-V)=0.026 mag so the intrinsic color is B-R=0.737 mag. corresponding
to a power-law spectral slope of -1.0.

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