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GCN Circular 20814

Subject
LIGO/Virgo G275404: Liverpool Telescope classification of EM candidates
Date
2017-03-04T19:25:27Z (7 years ago)
From
Chris Copperwheat at LJMU ArI <c.m.copperwheat@ljmu.ac.uk>
C.M.Copperwheat (LJMU), I.A.Steele (LJMU) and A.S.Piascik (LJMU) report on
behalf of

D.Bersier (LJMU), M.Bode (LJMU), C.Collins (LJMU), M.Darnley (LJMU),
D.Galloway (Monash), A.Gomboc (Nova Gorica), S.Kobayashi (LJMU), A. Levan
(Warwick), P.Mazzali (LJMU),  C.Mundell (Bath), E.Pian (Pisa), D. Pollacco
(Warwick),  D. Steeghs (Warwick), N.Tanvir (Leicester), K. Ulaczyk
(Warwick), K.Wiersema (Leicester)

and the GROWTH (Global Relay of Observatories Watching Transients Happen)
collaboration.

---

We report the following Liverpool Telescope follow-up observations of EM
candidates originally reported in GCNs #20790 and #20801. Observations were
made with the SPRAT spectrograph, and supernova classifications were
obtained using SNID (Blondin & Tonry, 2007, ApJ, 666, 1024).


iPTF17bug was observed on 2017-03-03 at 20:19UT. This is a nuclear source,
and the spectrum we obtain seems to be dominated by the host galaxy.

iPTF17bpa was observed on 2017-03-03 at 22:37UT. This source was reported
to be off-centre from it's host galaxy but we do not detect a transient
above the background galaxy emission in our acquisition image. The spectrum
seems to be galaxy dominated.

iPTF17bpt was observed on 2017-03-03 at 23:17UT. We classify this source as
a type Ia Supernova with z=0.074. A type Ib classification is also a
possibility. Note that this classification replaces the classification with
erroneously high z reported in GCN #20809.

iPTF17bsi was observed on 2017-03-04 at 04:56UT. SNID classifies this
source as a Type II supernova (possibly IIP) at 2.7 days after peak with
z=0.028. This is significantly higher than the photometric z = 0.014 reported
for the host galaxy in GCN #20790.

iPTF17btb was observed on 2017-03-04 at 05:29UT. We observe a bright point
source with a featureless spectrum - this is likely a dwarf nova in
outburst.
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