Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 16939

GRB 141022A: GROND Detection of a possible Optical Afterglow Candidate
2014-10-22T06:18:29Z (10 years ago)
Jochen Greiner at MPI <>
D.A. Kann (TLS Tautenburg), T. Schweyer, J. F. Graham, J. Greiner 
(all MPE Garching) report on behalf of the GROND team:

We observed the field of GRB 141022A (Swift trigger 616061; Vargas et
al., GCN #16938) simultaneously in g'r'i'z'JHK with GROND (Greiner et
al. 2008, PASP 120, 405) mounted at the 2.2 m MPG telescope at ESO La
Silla Observatory (Chile).

Observations started at 01:39 UT on October 22nd, approximately 20 min
after the GRB trigger. They were performed on a setting target at high
airmass (~2.7) until reaching the pointing limit.

Despite a crowed field we find only a single object in the 2.2"
Swift-XRT enhanced error circle reported by Vargas et al., GCN #16938) at

RA (J2000.0) = 16h 07m 28.82s
DEC (J2000.0) = -72d 07' 29.6"  

(error of 0".5) but cannot ascertain variability in images centered 
875 sec  and 2095 sec after the trigger, and note the possibility 
of a chance coincidence given the density of objects in the field.  
We intended subsequent observations to determine variability.

Based on a 16.5 min sequence of exposures, we estimate preliminary
magnitudes and limits (all in AB system) of:

g' = 23.6 +/- 0.2 mag
r' = 22.2 +/- 0.1 mag
i' = 21.6 +/- 0.1 mag
z' = 22.0 +/- 0.2 mag
J > 20.9 mag
H > 20.3 mag
K > 19.8 mag

Given magnitudes are calibrated against GROND zeropoints and 2MASS field
stars and are not corrected for the expected Galactic foreground
extinction corresponding to a reddening of E_(B-V)=0.1 mag in the
direction of the burst (Schlegel et al. 1998).
Looking for U.S. government information and services? Visit