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GCN Circular 19419

GRB 160509A Gemini North redshift
2016-05-10T16:43:15Z (8 years ago)
Nial Tanvir at U.Leicester <>
N. R. Tanvir (U. Leicester), A. J. Levan (U. Warwick),
S. B. Cenko (NASA/GSFC), D. Perley (DARK), A. Cucchiara (GSFC/STScI),
K. Roth (Gemini), K. Wiersema (U. Leicester), A. Fruchter (STScI), 
T. Laskar (NRAO/U.C. Berkeley) report on behalf of a larger collaboration:

We observed the optical counterpart of Fermi/LAT GRB 160509A
(Levan et al. GCN 19410) with the Gemini North telescope
on Mauna Kea, beginning at 2016-05-10 13:15 UT obtaining
both optical spectroscopy with GMOS-N and near-IR imaging
with NIRI.

Our spectroscopy covers a wavelength range of about 5900 AA
to 10100 AA, and reveals a single, well detected emission line
which we interpret as [OII] 3727 AA at a redshift of z=1.17 
(provisional analysis).  Alternative possible identifications for this 
line are ruled out by the absence of other lines in the spectrum.

Our infrared imaging shows the source, presumably some
combination of host and afterglow, to be very red with
K(Vega)~16.6 and J(Vega)~19.7 calibrated via 2MASS stars
in the field.  This would be consistent with a heavily dust
extinguished event. We also note that the source is apparently
unresolved in K-band seeing of 0.55 arcsec.

We acknowledge the excellent support of the Gemini staff,
in particular Michael Hoenig, and kind cooperation of the
visiting observers, in expediting these observations.  We also
thank Gemini Head of Science, Nancy Levenson, for approving 
this request.
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