[vsnet-grb-info 2931] GRB 060206: Confirmation of Rapid Fading at Optical Wavelengths

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  4768
SUBJECT: GRB 060206: Confirmation of Rapid Fading at Optical Wavelengths
DATE:    06/02/17 05:31:02 GMT
FROM:    Daniel E. Reichart at U.North Carolina  <reichart at physics.unc.edu>

D. Reichart, A. LaCluyze, M. Nysewander, and J. Haislip report on behalf of
the UNC team of the FUN GRB collaboration:

In addition to detecting the afterglow (Fynbo et al., GCN 4683) of GRB
060206 (Morris et al., GCN 4682) in I band 27.0 hours after the burst with
PROMPT (Kirschbrown et al., GCN 4712; LaCluyze et al., GCN 4750) and 51.3
hours after the burst with SOAR (LaCluyze et al., GCN 4750), we detected
the afterglow in i' band 26.0 hours after the burst with PROMPT, in V band
51.7 hours after the burst with SOAR, and in R band 51.9 hours after the
burst with SOAR.

At 26.0 hours after the burst, we measure i' = 19.83 +/- 0.22 mag.

>From our V and R photometry and a simple model of the Ly-alpha forest, we
infer i' = 21.55 +/- 0.08 mag at 51.8 hours after the burst.  (As a check,
simple interpolation between our R and I photometry yeilds i' = 21.36 +/-
0.05 mag at 51.6 hours after the burst.)  This implies a temporal index of
-2.3 +/- 0.3 between 26.0 and 51.8 hours after the burst, which is
consistent with and independent of our measurement of -2.20 +/- 0.26
between 27.0 and 51.3 hours after the burst in I band (LaCluyze et al., GCN
4750).

PROMPT and SOAR light curves can be viewed at:

http://www.physics.unc.edu/~reichart/grb060206.eps

Continued monitoring is strongly encouraged, particularly given that no
break is observed in X rays (Morris et al., GCN 4764).