GCN Circular 11025
Subject
GRB 100728B: Lick Observations
Event
Date
2010-07-29T05:59:34Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, C. R. Klein, and A. N. Morgan (UC Berkeley) report:
We began observations of the afterglow of GRB 100728B (Morris et al.,
GCN 11009; Perley et al., GCN 11007) with the Nickel 40-inch telescope
at Lick Observatory starting at 10:38:32 UT, 397 sec after the Swift
trigger. A series of frames in R-band (as well as one V-band and one
U-band exposure) was acquired. The resulting light curve shows a
gradual, unbroken power-law decay with a decay index consistent with
that seen in the KAIT observations (Perley et al., GCN 11024).
Photometry from our first seven R-band exposures is as follows:
tstart(s) exp(s) filt mag unc
397 60 R = 17.38 +/- 0.06
830 300 R = 18.33 +/- 0.05
1162 300 R = 18.53 +/- 0.06
1497 200 R = 18.71 +/- 0.07
1888 160 R = 18.88 +/- 0.09
2062 120 R = 18.80 +/- 0.09
2197 120 R = 18.99 +/- 0.11
Calibration is relative to a single bright star at RA=44.041108,
dec=+0.242409 (SDSS DR6 magnitudes g=15.61, r=14.52, i=14.57; the
equivalent Cousins R magnitude is R=14.3 using the average of the two
SDSS Lupton transformations.) As this star may be weakly blended with a
faint neighbor and its USNO magnitude (R2=13.94) differs from this SDSS
value, caution is advised in interpreting the absolute calibration.