[vsnet-grb-info 11244] GRB 111209A: Rebrightening seen by GROND
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Sun Dec 11 08:45:25 JST 2011
TITLE: GCN CIRCULAR
NUMBER: 12656
SUBJECT: GRB 111209A: Rebrightening seen by GROND
DATE: 11/12/10 23:45:21 GMT
FROM: Alexander Kann at TLS Tautenburg <kann at tls-tautenburg.de>
D. A. Kann (TLS Tautenburg), and J. Greiner, (MPE Garching)
report on behalf of the GROND team:
We have analyzed the J-band observations (Kann et al., GCN #12647)
obtained with GROND over a total of five hours (0.74 to 0.93 days after
the trigger) of GRB 111209A (Hoversten et al., GCN #12632). Astrometry and
calibration were obtained against the 2MASS catalog.
We find the afterglow experiences a strong rise during our observations,
rising from J ~ 19.3 to J ~ 18.8 (AB Magnitudes). The slope of the rise is
alpha < -2 (assuming F(t) propto t^-alpha). This behavior may be due to a
strong energy injection.
Highly variable behavior in the first hours has already been reported by
Klotz et al. (GCN #12637) and Hoversten & Siegel (GCN #12642).
Dense photometric follow-up is strongly encouraged.
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