[vsnet-grb-info 13787] GRB 130816A: GROND confirmation of afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15101
SUBJECT: GRB 130816A: GROND confirmation of afterglow
DATE:    13/08/16 10:39:08 GMT
FROM:    Jochen Greiner at MPI  <jcg at mpe.mpg.de>

K. Varela (MPE Garching), D.A. Kann, S. Klose (both TLS Tautenburg), 
J. Elliott and J. Greiner (both MPE Garching) report on behalf of 
the GROND team:
  
We observed the field of GRB 130816A (Holland et al., GCN #15097)
simultaneously in g'r'i'z'JHKs with GROND (Greiner et al. 2008, PASP 120,
405) mounted at the 2.2 m MPG/ESO telescope at La Silla Observatory 
(Chile). 
  
Observations started at 01:49 UT on 16 August 2013, 3 min after the GRB
trigger. We confirm the presence of the NIR source inside the 2.2 arcsec
Swift-XRT error circle (Holland et al.) found by Covino et al. 
(GCN 15098).
  
Based on the first 140 sec g'r'i'z and 240 sec JHK exposure,
we estimate preliminary magnitudes (all in AB) of      
  
g' = 21.8 +/- 0.2 mag,
r' = 20.3 +/- 0.1 mag,
i' = 19.5 +/- 0.1 mag,         
z' = 18.9 +/- 0.1 mag,         
J = 18.0 +/- 0.1 mag,
H = 17.4 +/- 0.1 mag, and      
K = 17.1 +/- 0.1 mag,
  
calibrated against GROND zero points (g'r'i'z') and 2MASS (JHK).
Correcting for the Galactic foreground extinction corresponding to 
a reddening of E_(B-V)= 0.80 in the direction of the burst 
(Schlegel et al. 1998), the SED is well fit with a powerlaw of
slope 0.8, typical of GRB afterglows.

The object rapidly faded (by about 1.5 mag) during the following 
40 min., leaving no doubt that this is the afterglow of GRB 130816A.