Swift observation of OGLE17jei = SN 2017jei
ATel #11143; K. Sokolovsky (IAASARS NOA/ASC Lebedev/SAI MSU), M. Gromadzki, L. Wyrzykowski (Warsaw Observatory), A. Udalski, I. Soszynski, K. Ulaczyk, J. Skowron (Warsaw Observatory, on behalf of the OGLE team), R. Roy (IUCAA)
on 9 Jan 2018; 17:05 UT
Credential Certification: Kirill Sokolovsky (kirx@scan.sai.msu.ru)
Subjects: Optical, Ultra-Violet, X-ray, AGN, Black Hole, Supernovae, Transient, Tidal Disruption Event
The optical transient OGLE17jei = SN 2017jei was detected on
2017-11-15 in a face-on galaxy MRSS 054-118874. OGLE-IV deep stack
image shows the host galaxy has an extended central feature (bulge
or/and bar) and the position of the transient coincides with S-E
part of this structure. It could not be ruled out that the
transient is associated with the central black hole.
The OGLE-IV photometry suggests the transient was slowly rising
from below the detection limit around I=21.5 for the past 60 days
(latest non-detection on 2017-11-11), about a week ago it suddenly
increased its rate of brightening reaching a peak at I=17.1 on
2018-01-06. Spectroscopic observations with the NTT (ePESSTO,
ATel #11114) were inconclusive suggesting this may be
a Type IIn SN, TDE or an AGN flare at z=0.058.
Swift observed OGLE17jei for 1.0ks on 2018-01-07. Swift/XRT
detected no X-ray source at the position of the transient with
an upper limit of 0.005 +/-0.002 cts/s. Assuming power law
emission with the photon index of 2 and HI column density of
4.16x10^20 cm^-2 this translates to the unabsorbed 0.3-10 keV
flux limit of 2x10^-13 ergs/cm^2/s.
An ultraviolet source is detected at the position of the transient
with the following UVOT magnitudes (Vega system):
Band Mag. Err.
UVW2 16.78 0.06
UVM2 16.55 0.09
UVW1 16.49 0.07
U 16.52 0.07
B 17.57 0.09
V 17.39 0.14
We also use the UVOT images to measure the position of OGLE17jei:
03:14:11.94 -71:12:25.5 +/-0.1" J2000 which is 1.1" from the
reported position of the host galaxy. Taking into account the
Galactic reddening of E(B-V)=0.033 (Schlafly et al. 2011 ApJ,
737, 103) the ultraviolet magnitudes correspond to the color
temperature of about 14000 K, consistent with OGLE17jei
being a peculiar Type IIn supernova.
We thank the Swift team for rapid execution of this observation.
We acknowledge the OGLE-IV Transient Detection System presented in
ATel #4495; Kozlowski et al. 2013, AcA, 63, 1, 1;
Wyrzykowski et al. 2014, AcA, 64, 197
OGLE17jei = SN 2017jei at the Transient Name Server
