TCP J18010186-2951258

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TCP J18010186-2951258

Postby Olivier GARDE » Sat Jul 14, 2018 9:16 am

New CBAT about this object :
http://www.cbat.eps.harvard.edu/unconf/ ... 51258.html

Christian and I made a spectrum of this target last night at the OHP during the annual spectro party and the spectra we got is visible here:
https://www.aavso.org/tcp-j18010186-295 ... agittarius

Very strange spectrum and at this date no confirmation about this kind of object.

Could be either a microlensing event and highly obscured supernova in milky Way (according to discussion in Facebook cataclysmic variables forum :
https://www.facebook.com/groups/7122470 ... st_mention
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Re: TCP J18010186-2951258

Postby Robin Leadbeater » Sat Jul 14, 2018 9:18 pm

Olivier GARDE wrote:New CBAT about this object :
highly obscured supernova in milky Way (according to discussion in Facebook cataclysmic variables forum :


Really ?? This would be extraordinary if it turns out to be true. Any neutrinos seen ? (Facebook is a place I avoid)
It is too low for me but definitely sounds like one to watch

Robin
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Re: TCP J18010186-2951258

Postby Francois Teyssier » Sun Jul 15, 2018 7:35 am

Lorenzo Franco also got a spectrum of the event

tcpj18010186-2951258_20180713_902_LFranco.png


ATel about the event:

ATEL #11853 ATEL #11853

Title: ASAS-SN Confirmation of a Bright and Possible High-Magnification
Microlensing Event
Author: Subo Dong (KIAA-PKU), K. Z. Stanek, C. S. Kochanek, T. Jayasinghe,
T. A. Thompson (OSU), J. L. Prieto (Diego Portales; MAS), B. J. Shappee
(Univ. of Hawaii), T. W.-S. Holoien (Carnegie)
Queries: dongsubo@pku.edu.cn
Posted: 14 Jul 2018; 16:51 UT
Subjects:Optical, Microlensing Event

The transient <a href=http://www.cbat.eps.harvard.edu/unconf/followups/J18010186-2951258.html>TCP
J18010186-2951258</a> was first discovered by T. Kojima on UT 2018 07
13.494. The <a href=https://asas-sn-s.asc.ohio-state.edu/light_curves/40857b7e-c8ad-4144-91a9-1ad5f12d66ee>ASAS-SN
Sky Patrol light curve </a> (Shappee et al. 2014; Kochanek et al. 2017)
suggested this to be a probable microlensing event. We take i-band follow-up
images with 40cm robotic telescopes of the Las Cumbres Observatory, and
the refined coordinates based on the follow-up observations are: (RA =
18:01:01.84 Dec=-29:51:23.8).

ASAS-SN has been regularly observing the field containing TCP J18010186-2951258
since 2016-03-10. The latest ASAS-SN photometry on UT 2018-07-14.1132905
shows that the source is at V = 10.73, and this is brighter than all previous
ASAS-SN measurements. The light curve is consistent with single-lens microlensing
models. Since we only have the rising part of the light curve, and due
to the degeneracy of blending, there are a number of single-lens microlensing
models compatible with data. One possible (though not unique) class of
microlensing models expect the event reaching high peak magnification on
around UT 2018 07 15 (<a href=http://www.astronomy.ohio-state.edu/~assassin/followup/TCPJ18010186-2951258.pdf>see
an example model here</a>). A high-magnification microlensing event is
sensitive to planets orbiting the lens star, and high-cadence photometric
follow ups are encouraged in the near future.

We thank Las Cumbres Observatory and its staff for their continued support
of ASAS-SN. ASAS-SN is funded in part by the Gordon and Betty Moore Foundation
through grant GBMF5490 to the Ohio State University, NSF grant AST-1515927,
the Mt. Cuba Astronomical Foundation, the Center for Cosmology and AstroParticle
Physics (CCAPP) at OSU, and the Chinese Academy of Sciences South America
Center for Astronomy (CASSACA).
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Re: TCP J18010186-2951258

Postby Robin Leadbeater » Sun Jul 15, 2018 10:36 am

I spoke to Subo Dong last night and pointed him to the spectra. (I sometimes work with him and the ASASSN team on supernovae) Even if it turns out to be a microlensing event, the question still remains what type of star is this ? Subo does not think this is a CV. What does the spectrum look like with the Telluric and IS lines removed? Assuming it is a hot star with very high extinction, what objects have a narrow H alpha in absorption and no other obvious stellar features ?

Cheers
Robin
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