TITLE:   GCN CIRCULAR
NUMBER:  10547
SUBJECT: GROND observations of GRB100316D/SN2010bh
DATE:    10/03/26 22:58:43 GMT
FROM:    Arne Rau at MPE  <arau@mpe.mpg.de>

Arne  Rau, Marco Nardini  (both MPE  Garching), Adria  Updike (Clemson
University), Robert  Filgas, Jochen Greiner, Thomas  Kruehler (all MPE
Garching), and Sylvio  Klose (TLS Tautenburg) report on  behalf of the
GROND team:

We  report on  additional observations  of  the field  of GRB  100316D
(Swift trigger 416135; Stamatikos et al., GCN 10496) simultaneously in
g'r'i'z'JHK with GROND (Greiner et al. 2008, PASP 120, 405) mounted at
the  2.2  m  MPI/ESO   telescope  at  La  Silla  Observatory  (Chile).
Observations started  on 17 March 2010  at 00:27 UT,  11.7 hours after
the burst (Afonso et al., GCN Circular #10514). The field was observed
during additional 16 epochs and observations are continuing.

Image subtraction revealed the supernova SN2010bh reported by Wiersema
et al.  (GCN Circular #10525),  Chornock et al. (GCN Circular #10541),
and Bufano  et al.   (GCN Circular #10543)  to emerge approx.   5 days
post-burst and  to reach an AB  magnitude of r  ~ 18.8 +/- 0.2  at 7.5
days post-burst.

The observed light  curve evolution of SN2010bh is  similar to that of
SN1998bw  (Galama  et  al.    1998),  the  supernova  associated  with
GRB980425, shifted to the  redshift of GRB100316D (z=0.059; Vergani et
al., GCN  Circular #10512).  The  optical luminosity is  comparable to
SN1998bw,  except in  the  g-band,  where the  flux  is suppressed  by
approx.   30%.   This  likely  corresponds  to  the  significant  flux
deficiency in the range 450-550nm reported from the X-Shooter spectrum
(Bufano et al., GCN Circular #10543).