[vsnet-grb-info 3353] GRB 060526: Multiple Optical Flares

[GCN Circulars]

TITLE:   GCN GRB OBSERVATION REPORT
NUMBER:  5188
SUBJECT: GRB 060526: Multiple Optical Flares
DATE:    06/05/30 21:34:18 GMT
FROM:    Jules Halpern at Columbia U.  <jules at astro.columbia.edu>

J. P. Halpern (Columbia U.), E. Armstrong (UCSD), & N. Mirabal (U. Michigan) 
report on behalf of the MDM Observatory GRB follow-up team:

"We have continued to observe the afterglow of Swift GRB 060526 (Campana 
et al. GCN 5162) in the R-band for four consecutive nights using the
MDM 1.3m.  In combination with the GCN reported R-band photometry of 
Khamitov et al. (GCNs 5173,5177,5183,5186), it is evident that there have
been at least four flares, by which we mean alternating positive and
negative deviations from a mean decay rate.  These are characterized
as increases and decreases of at least 0.3 mag in as short a time as
delta t = 0.04*(t-t0), where t0 is the burst time.  In view of these
flares, it is problematic to fit a small number of power-law segments
(as noted by Kann & Thoene GCN 5187).  Rather, we observe that the most 
recent point, r' = 22.87+/-0.07 on May 30 04:23 UT as calibrated with
Cool et al. (GCN 5164) data, falls only 0.25 mag below the -1.18 power
law originally fitted from 5.6 to 16 hours by Khamitov et al. (GCN 5173)
and Halpern et al. (GCN 5176).  Other details of the MDM optical light
curve and incorporated GCN data can be seen at:

http://www.astro.columbia.edu/~jules/grb/060526/

This type of light curve is not uncommon in GRB afterglows (see, e.g.,
Stanek et al. astro-ph/0602495, and references therein), and is often
apparent when the source is well placed for long observing runs at
ground-based telescopes."