[vsnet-grb-info 15701] GRB 141028A: P60 Observations and Decay Index

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16989
SUBJECT: GRB 141028A: P60 Observations and Decay Index
DATE:    14/10/30 03:42:40 GMT
FROM:    S. Bradley Cenko at NASA/GSFC  <brad.cenko at nasa.gov>

S. B. Cenko (NASA/GSFC) and D. A. Perley (Caltech) report on behalf of a larger collaboration:

We have imaged the location of the optical afterglow (Gorbovskoy et al., GCN 16972) of the Fermi GBM (Roberts et al., GCN 16971) and LAT (Bissaldi et al., GCN 16969) GRB141028A with the robotic Palomar 60 inch telescope.  Using nearby point sources from the Sloan Digital Sky Survey for reference, we measure the following r'-band magnitudes in our P60 images:

r' = 20.09 +/- 0.06 at dt = 15.8 hr after the burst
r' = 21.00 +/- 0.05 at dt = 39.3 hr after the burst

Based on these observations, we infer a power-law decay index of alpha ~ 0.9.