GCN Circular 18536
Subject
LIGO/Virgo G194575: INAF-TNG follow-up of iPTF15dkm and iPTF15dlj
Date
2015-10-30T13:45:34Z (9 years ago)
From
Silvia Piranomonte at INAF <silvia.piranomonte@oa-roma.inaf.it>
P. D'Avanzo, A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), E. Cappellaro, L. Tomasella (INAF-OAPd), E. Brocato (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), E. Palazzi (INAF-IAFS Bo), L. A. Antonelli, (INAF-OAR), P. Astone (INFN-Roma), S. Campana (INAF-OAB), E. Cappellaro (INAF-OAPd), S. Covino (INAF-OAB), V. D'Elia (INAF-ASDC), F. Getman (INAF-OAC), G. Giuffrida (INAF-ASDC), A. Grado (INAF-OAC), G.Greco (Urbino University/INFN Firenze), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), S. Marinoni (INAF-ASDC), P. Marrese (INAF-ASDC), L. Nicastro (INAF-IASF Bo), Pian (SNS-Pisa), L. Pulone (INAF-OAR), F. Ricci (Sapienza University), G. Stratta (Urbino University/INFN Firenze), V. Testa (INAF-OAR), A. Fiorenzano, W. Boschin, Albar Garcia de Gurtubai Escudero (INAF-TNG), on behalf of the INAF Gravitational Astronomy group report:
We report the result of the analysis of the optical transients iPTF15dkm and iPTF15dlj reported by Singer et al. (LIGO/Virgo Circular #18497), located in the skymap of the advanced LIGO and Virgo trigger G194575 (Singer et al., LIGO/Virgo Circular #18442).
We observed with the 3.6m Italian TNG telescope (Canary Islands, Spain), equipped with DOLORES camera in both imaging and spectroscopic mode on 2015 Oct 29.
The optical transients are clearly detected. At a mean time of 20:07:03 UT and 20:50:24 UT we measure a magnitude of r = 17.95 +/- 0.23 (AB) and r = 16.64 +/- 0.35 (AB) for iPTF15dkm and iPTF15dlj respectively.
Based on a preliminary calibration, the spectrum of iPTF15dkm, obtained on
2015 Oct 29 at 20:57:30 UT, shows that the transient is a Type II SN
about ten days after explosion at z~0.026, as derived from the position of
the SN main features. The best fit is with SN2006bp (Quimby et al. 2007, ApJ 666, 1093).
The transient is close to SDSS galaxy SDSS J233717.65-033159.2,
with photometric redshift z~0.036.
The spectrum of iPTF15dlj, obtained on Oct 29 at 21:37:46 UT, shows that
the transient is a type II SN about 2-3 weeks after explosion, around z~0.01.
The best match is with SN 2005cs (Pastorello et al. 2006,
MNRAS, 370, 1752). The transient is close to the galaxy J011902.90+100005.5
(photometric redshift z~0.05 from SDSS).
Classification was done with GELATO (Harutyunyan et al. 2008, A&A, 488, 383)
and SNID (Blondin and Tonry 2007, ApJ, 666, 1024).