GCN Circular 10927

Subject

GRB 100526A: Gemini/NIRI afterglow confirmation and host galaxy

Event

Date

2010-07-02T22:51:48Z (15 years ago)

From

Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>

D. A. Perley, J. S. Bloom, and S. B. Cenko (UC Berkeley) report:

We re-observed the field of GRB 100526A (Vetere et al., GCN 10797Loading...
 
 ) with 
NIRI on Gemini-North between 08:30 and 09:00 UT on 2010-06-24 UT.  We 
acquired 27 images of 60 seconds each in K-band.

Comparison to our previous K-band imaging of this field (Perley et al., 
GCN 10806Loading...
 
 ) shows the infrared counterpart to have faded significantly. 
A source is still detected at high significance at the afterglow 
position.  Using the same 2MASS reference star as for our previous 
epoch, we measure a magnitude of:

K = 21.2 +/- 0.2   (t_mid = 27.7 days)

This corresponds to a decay index (t^-alpha) of only alpha~0.5 from our 
previous epoch, which is much slower than expected for a late-time 
afterglow, and suggests that the current epoch is likely host-galaxy 
dominated.

A comparison image is posted to:
http://lyra.berkeley.edu/~dperley/100526a/100526a_niri.png