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ASASSN-15lo is a Post-Maximum Normal Type Ia Supernova

ATel #7675; D. C. Leonard (San Diego State University), P. Sheehan, D. McCarthy (University of Arizona), K. Follette (Stanford University), J. Moustakas (Siena College), D. Cantillo, A. Cazares-Kelly, S. Cazares-Kelly, Y. Cendes, N. Damm, A. Donati, E. Douglas, L. Ferrell, H. Fosbiner-Elkins, C. Fox, M. Greenberg, K. Hart, H. Hensley, A. Holt, E. Hooper, C. Juran, J. Keane, K. Key, L. Korus, T. Lee, K. Leidig, E. Merchak, K. Nessmann, S. Pendyala, S. Pirkl, J. Reeder, A. Roos, S. Rounseville, E. Ruddy, A. Schlingman, W. Schlingman, W. Schlingman, E. Schwartzman, V. Shanmugam, E. Silver, A. Stein, N. Stock, B. Svoboda, B. Thomas, N. Thomas, K. Thompson-Taylor, H. Walton (2015 Advanced Teen Astronomy Camp)
on 20 Jun 2015; 17:28 UT
Credential Certification: D. C. Leonard (leonard@astro.caltech.edu)

Subjects: Optical, Supernovae

We report spectroscopic classification of ASASSN-15lo (ATel #7673) through inspection of a low-dispersion optical spectrum (range 370-680 nm), obtained with the 2.3-m Bok telescope (+ Boller & Chivens spectrograph) at Kitt Peak on 2015 June 20 UT.

ASASSN-15lo is a Type Ia supernova; cross-correlation with a library of supernova spectra using the "Supernova Identification" code (SNID; Blondin and Tonry 2007, ApJ, 666, 1024) finds best matches with a number of normal type-Ia supernovae at a redshift of 0.04 roughly 11 days after maximum light. An expansion velocity of 10,078 km/s is derived from the position of the Si-II (rest 635.5 nm) minimum. We note that the spectroscopically derived (post-maximum) age of this supernova is in some tension with the discovery photometry described by ATel #7673, which would suggest a pre-maximum phase at the time of our observation; the uncertainties on the preliminary photometric measurements (not explicitly given by ATel #7673), however, may be quite large and so the increasing brightness indicated over the past several days may not be significant.