[vsnet-grb-info 15006] GRB 140518A: P60 i-/z-band detections

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  16300
SUBJECT: GRB 140518A: P60 i-/z-band detections
DATE:    14/05/18 12:22:01 GMT
FROM:    Daniel Perley at Caltech  <dperley at astro.caltech.edu>

D. A. Perley (Caltech) reports on behalf of a larger collaboration

The Palomar 60-inch telescope responded automatically to the Swift 
trigger for GRB 140518A (Melandri et al., GCN 16298) and began a 
repeating cycle of 60-second exposures in r, i, and z-band observations 
at 09:22:28 UT, 4.70 minutes after the burst.

We weakly detect the afterglow reported by Zheng et al. (GCN 16299) in 
the i and z filters, but not in r-band.   Only marginal detections are 
evident in any individual exposure in any filter, but a stack of the 
first six exposures in each band gives magnitudes (calibrated relative 
to SDSS) of:

r > 20.31  (2 sigma)
i = 19.03 +/- 0.16
z = 18.20 +/- 0.17

at a mid-time of approximately 16 minutes after the burst.