GCN Circular 17756
Subject
GRB 150424A: NOT optical observations
Event
Date
2015-04-24T23:08:53Z (11 years ago)
From
Daniele Malesani at Dark Cosmology Centre, Niels Bohr Inst <malesani@dark-cosmology.dk>
D. Malesani (DARK/NBI), D. Xu (NAOC/CAS), D. J. Watson (DARK/NBI), and
P. Blay (IAC/NOT), report on behalf of a larger collaboration:
We observed the optical counterpart (Perley, GCN 17745; Marshall &
Beardmore, GCN 17751) of the short GRB 150424A (Beardmore et al., GCN
Circ. 17743), using the Nordic Optical Telescope equipped with the
AlFOSC camera. The first 300-s R-band exposure was taken starting at
20:57 UT (13.2 hr after the GRB)
We clearly detect the counterpart with a magnitude R = 20.67 +- 0.06
(assuming R = 16.27 for the USNO star at RA = 10:09:11.09, Dec =
-26:36:58.4).
This magnitude is just slightly fainter than the value reported by
Perley (GCN 17745) 1.6 hr after the trigger, indicating a very slow
decay - consistent with the UVOT report. The brightness of the afterglow
is unprecedented for a short GRB this late after the GRB. Such a
behaviour is unusual and we encourage further observations.