Kron-Cousins Optical Photometry of SN 2009ip

ATel #4430; D. C. Leonard; J. M. Fedrow; H. G. Khandrika (San Diego State University); and L. Gonzalez (University of California, San Diego)
on 27 Sep 2012; 14:27 UT
Credential Certification: D. C. Leonard (leonard@astro.caltech.edu)

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Following a report (Smith & Mauerhan, ATel #4412) of spectral changes on 2012 Sept. 15 and 16 (JD 2456185 and JD 2456186) that suggested a transition from LBV-like eruptions (Smith et al. 2010; Foley et al. 2011; Drake et al. 2012, ATel #4334) to a true SN IIn explosion, photometric observations of the transient SN 2009ip have indicated dimming (Margutti et al., ATel #4414; Martin et al., ATel #4416) followed by significant recent brightening (Brimacombe, ATel #4423; Margutti et al., ATel #4425) of the transient.

Here we report Kron-Cousins (B, V, R_C, I_C) photometric observations of SN 2009ip taken at the 40'' reflecting telescope at Mount Laguna Observatory that cover the pre- and post-brightening epochs of this transient in a single, standard photometric system. The data indicate that the object has increased in brightness by 3 to 3.5 mag in all four photometric bands in the past three days.

JD	Filter	Mag	Mag_err
2456192.77	R_C	17.88	0.38
2456194.72	B	18.07	0.06
2456194.70	V	17.70	0.05
2456194.68	R_C	17.68	0.18
2456194.71	I_C	16.85	0.10
2456197.82	B	14.54	0.08
2456197.76	V	14.45	0.05
2456197.74	R_C	14.53	0.19
2456197.83	I_C	13.74	0.10

Calibrations were provided by a sequence of from 8 to 12 local standards, with B and V values for the local standards taken from the UCAC4 catalog (Zacharias et. al. 2012); R values from the USNO-A2.0 catalog (Monet et al. 1998) with translation to R_C provided by Kidger 2003 (http://www.britastro.org/asteroids/USNO%20photometry.htm); and I values provided by the USNO-B1.0 catalog (Monet et al. 2003). No corrections have been made for Galactic extinction [E(B-V) = 0.03; Schlegel et al. 1998], or host-galaxy contamination in the images. Reported uncertainties represent the 1-sigma scatter in the calibrations provided by the local standards added in quadrature to the photometric uncertainty in the SN 2009ip measurements.

When compared with previously reported observations, these data provide some evidence that the recent brightening was initiated at NIR wavelengths prior to the UV; it also suggests that the object has continued to brighten in the past day. Uncertainty in the relative calibration among all of the datasets, however, make definitive statements difficult to make.

D.C.L. thanks the NSF for support through AST-1009571 and AST-1210311 and the Laboratoire d'Astrophysique de Marseille for hospitality during his sabbatical leave.