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iPTF Discovery of a Young Transient in a Tidal Tail of NGC 5221

ATel #8907; A. A. Miller (JPL/Caltech), R. Laher, F. Masci, J. Surace (IPAC), U. Rebbapragada, B. Bue, G. Doran (JPL), E. Bellm, Y. Cao, M. Kasliwal, S. Kulkarni (Caltech), on behalf of the intermediate Palomar Transient Factory
on 5 Apr 2016; 02:24 UT
Credential Certification: Adam Miller (amiller@astro.caltech.edu)

Subjects: Supernovae, Transient

Referred to by ATel #: 8909, 8910, 8937

We report the detection of a new transient candidate identified via automated processing of intermediate Palomar Transient Factory (iPTF; Atel#4807) observations. The transient, named iPTF 16abc, was discovered on 2016-04-04.39 UT with g = 19.2 mag. The candidate was automatically identified by the real-time processing pipeline at the Infrared Processing and Analysis Center (IPAC). The iPTF IPAC pipeline uses custom image subtraction software, PTFIDE ( Masci et al., in prep ), and candidates are automatically vetted and ranked using an updated version of previously developed PTF real-bogus software (Rebbapragada et al. 2015AAS...22543402R).

iPTF 16abc is located at R.A., Dec = 13:34:45.492 +13:51:14.30 (J2000), roughly 170 arcsec (~85 kpc) from the nucleus of NGC 5221. Deep iPTF co-add imaging shows the presence of a tidal tail extending from NGC 5221 to the position of iPTF 16abc. The tidal tail is likely due to interactions with the nearby elliptical galaxy NGC 5222, at a similar redshift and located to the south of NGC 5221.

The transient was not detected in images obtained the night prior to detection, 2016-04-03 UT, to a detection limit of g > 21 mag. Adopting a distance modulus of 34.95 mag to NGC 5221, the absolute magnitude of iPTF 16abc at the time of discovery is M_g = -15.8 mag. The non-detection the night before discovery implies a very fast rise (~2 mag/d), suggesting the transient could be a young supernova.

We have triggered Gemini for optical spectroscopy, Swift for UV imaging, and AMI for radio observations. Additional follow-up at all wavebands is highly encouraged.

Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Copyright 2016. All rights reserved.