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GCN Circular 18807

Subject
LIGO/Virgo G211117: Liverpool Telescope classification of EM candidates
Date
2016-01-02T18:50:49Z (8 years ago)
From
Chris Copperwheat at LJMU ArI <c.m.copperwheat@ljmu.ac.uk>
We report the following spectroscopic observations and classifications
of a number of the EM candidates reported by Cenko et al. in GCN
18762. All observations were obtained using the 2.0 metre Liverpool
Telescope, La Palma by C.M. Copperwheat & I.A. Steele (Liverpool JMU)
on behalf of a wider collaboration.

iPTF-15fhp was observed with the SPRAT spectrograph on 2016-01-01 at
00:58UT. The spectrum was of quite poor quality and SNID (Blondin &
Tonry, 2007, ApJ, 666, 1024) provides a tentative classification of a
type Ia supernova approximately one week before peak. We have
scheduled a second observation to test this classification.

iPTF-15ffz was observed with the SPRAT spectrograph on 2016-01-01 at
19:26UT. A number of emission lines are observed: including OII,
H-beta and H-alpha with a common redshift of 0.070. This is consistent
with the SDSS photometric redshift of the proposed host galaxy
(z=0.075). We believe this target to be an AGN.

iPTF-15fed was observed with the SPRAT spectrograph on 2016-01-01 at
20:03UT. We do not see a point source distinct from the galactic
emission in our acquisition image, however we estimate the limiting
magnitude of this image is R~19.1, compared to the transient magnitude
of 19.9 reported by iPTF. The spectrum we obtain is dominated by
emission from the host galaxy.

iPTF-15fib was observed with the SPRAT spectrograph on 2016-01-01 at
20:39UT. We do not detect an object at those coordinates in our
acquisition image. We estimate the limiting magnitude of this image is
R~19.5, which is the same as the transient magnitude reported by iPTF.
The spectrum we obtained was blank. Possibly this object has faded.

iPTF-15ffk was observed with the SPRAT spectrograph on 2016-01-01 at
21:16UT. Classification using SNID indicates the transient is a type
Ia supernova with z = 0.108 -/+ 0.005 at 6.9 days past peak. This
redshift is consistent with the SDSS photometric redshift of the
proposed host galaxy (z=0.11).

iPTF-15fgy was observed with the SPRAT spectrograph on 2016-01-01 at
21:55UT. Classification using SNID indicates the transient is a type
Ia supernova with z = 0.072 -/+ 0.006 at 16.8 days past peak.
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