Independent discovery and spectroscopic classification of iPTF16bqy (ASASSN-16hf) as a Classical Nova in M31

ATel #9248; K. Chinetti (Caltech), M. J. Darnley (LJMU), M. M. Kasliwal (Caltech), P. Mazzali (LJMU), J. D. Neill (Caltech), S. C. Williams (Lancaster)
on 15 Jul 2016; 18:59 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)

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We report the independent discovery of nova candidate iPTF16bqy (ASASSN-16hf; ATel #9245) on 2016 July 12.44 UT with the intermediate Palomar Transient Factory. iPTF16bqy is located at RA 00:44:41.05, DEC +40:08:35.9 (J2000.0; consistent with the ASASSN position), and was not detected in images taken 2016 July 10.47 and earlier. Photometry of the transient with the Samuel Oschin 48-inch telescope is summarized in the table below:

 
Date (UT)          Filter    Magnitude 
2016 July 12.44    r         18.76 ± 0.05 
2016 July 13.47    r         17.03 ± 0.06 
2016 July 14.44    r         16.32 ± 0.06 
2016 July 15.43    r         16.71 ± 0.07 

We also obtained a pair of spectra with the SPRAT spectrograph (Piascik et al. 2014) on the 2m Liverpool Telescope (Steele et al. 2004) on 2016 July 14.12 and 15.07 UT. An additional spectrum was obtained with the SEDM spectrograph on the Palomar 60-in telescope on 2016 July 14. The spectra show Balmer (Hα-δ) P Cygni profiles, consistent with the early optically thick phase of a classical nova eruption (the 'fireball'). The Hα P Cygni profiles indicate ejection velocities of 2300 ± 100 km/s. The spectra also show Fe II (multiplets 42, 73, 74), Na I (5892 Å), and O I (7713 Å) emission lines, with hints of blue shifted absorption components. Clear evolution of the P Cygni profiles is evident between the spectra with the absorption features weakening and the emission strengthening as the ejecta expands. As such we conclude that iPTF16bqy is the early stage of an eruption of a classical nova in M31 and belongs to the Fe II taxonomic class.

Finally, we comment that the large distance of this nova from the center of M31 (4053" South and 1338" East of the center of M31; ATel #9245) is in itself noteworthy. The emission line centers and the luminosity of this nova are however, consistent with the nova belonging to M31.

This work is part of an international undergraduate internship supported by the NSF PIRE GROWTH program.