GCN Circular 18779
Subject
LIGO/Virgo G211117: LBT Follow-up of iPTF15fen
Date
2015-12-31T06:13:42Z (9 years ago)
From
Peter Garnavich at Notre Dame <pgarnavi@nd.edu>
P. Garnavich (Notre Dame) reports:
R. Pogge (OSU), J. Turner (UVa), and B. Rothberg (LBTO) obtained LBT/MODS
spectra of iPTF15fen (Cenko et al., GCN 18762), the "hostless" candidate
at 03:21:37.544 +31:27:08.1 (J2000). Spectra were taken 2015 Dec. 31.1 (UT)
and cover 330 nm to 1.0 microns.
The r-band acquisition image shows an unresolved source at the position of
the iPTF transient. The red Digitized Sky Survey (DSS) image from 1992
also shows this source.
The combined spectrum reveals a blue continuum with broad and
extremely weak absorption features. The clearest features
correspond to Balmer absorption lines of H-beta, H-gamma,
and H-delta at low velocity. The source is likely a
hydrogen-rich accretion disk in outburst.
iPTF15fen is probably a Galactic dwarf nova or a nova-like
cataclysmic variable. No narrow emission is detected at the
center of the Balmer absorption features as often seen in
outbursting disks, but this may be due to the low signal-to-noise
ratio of these features.