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New JAAVSO preprint: Early-time flux measurements of SN 2014J

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Early-Time Flux Measurements of SN 2014J Obtained with Small Robotic Telescopes: Extending the AAVSO Light Curve

Björn Poppe
Thorsten Plaggenborg

Universitätssternwarte Oldenburg, Institute of Physics, Carl von Ossietzky University Oldenburg, Germany

WeiKang Zheng
Isaac Shivvers

Department of Astronomy, University of California, Berkeley, CA 94720-3411

Koichi Itagaki
Itagaki Astronomical Observatory, Teppo-cho, Yamagata 990-2492, Japan

Alexei V. Filippenko
Department of Astronomy, University of California, Berkeley, CA 94720-3411

Jutta Kunz
Universitätssternwarte Oldenburg, Institute of Physics, Carl von Ossietzky University Oldenburg, Germany

Received December 9, 2014; revised April 14, 2015; accepted May 20, 2015

Abstract

In this work, early-time photometry of supernova (SN) 2014J is presented, extending the AAVSO CCD database to prediscovery dates. The applicability of NASA’s small robotic MicroObservatory Network telescopes for photometric measurements is evaluated. Prediscovery and postdiscovery photometry of SN 2014J is measured from images taken by two different telescopes of the network, and is compared to measurements from the Katzman Automatic Imaging Telescope and the Itagaki Observatory. In the early light-curve phase (which exhibits stable spectral behavior with constant color indices), these data agree with reasonably high accuracy (better than 0.05 mag around maximum brightness, and 0.15 mag at earlier times). Owing to the changing spectral energy distribution of the SN and the different spectral characteristics of the systems used, differences increase after maximum light. We augment light curves of SN 2014J downloaded from the American Association of Variable Star Observers (AAVSO) online database with these data, and consider the complete brightness evolution of this important Type Ia SN. Furthermore, the first detection presented here (Jan. 15.427, 2014) appears to be one of the earliest observations of SN 2014J yet published, taken less than a day after the SN exploded.

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