[vsnet-grb-info 17140] GRB 151027A: P60 afterglow confirmation and rebrightening

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18481
SUBJECT: GRB 151027A: P60 afterglow confirmation and rebrightening
DATE:    15/10/27 05:57:03 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

D. A. Perley (DARK/NBI) and S. B. Cenko (NASA/GSFC) report:

The Palomar 60-inch robotic telescope responded automatically to the 
alert for GRB 151027A (Maselli et al., GCN151027A) and began a sequence 
of i, r, and z-band imaging at 04:00:49 UT, 145 seconds after the BAT 
trigger.   We identify a very bright afterglow consistent with the UVOT 
and KAIT (Zheng et al., GCN18479) positions in all filters.

The preliminary afterglow light curve shows a slow rise to a peak at 
about ~5 minutes after the GRB trigger, then slowly fades by about 1 
magnitude between then and approximately 30 minutes after the trigger. 
Over the next 20 minutes it then rapidly rebrightens by about 0.7 
magnitude.  Little or no fading is seen after that point (through to at 
least 90 minutes after the trigger.)

Continued monitoring is encouraged, and should remain possible even from 
small telescopes for quite some time.  High-resolution spectroscopy is 
also strongly encouraged.