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SN2009ip: Brightening Rapidly

ATel #4423; J. Brimacombe (Coral Towers Observatory)
on 25 Sep 2012; 20:45 UT
Credential Certification: Andrew J. Drake (ajd@cacr.caltech.edu)

Subjects: Optical, Supernovae, Variables

Referred to by ATel #: 4425, 4427, 4430, 4431, 4435, 4439, 4479

On 2012 Aug. 24 Drake et al. (2012, ATel#4334) reported a new outburst from supernova impostor (LBV) SN 2009ip (Smith et al., 2010, AJ, 139, 1451; Foley et al., 2011, ApJ, 732, 32). Observations by Foley et al. (2012, Atel#4338) on Aug 26 UT showed an outburst spectrum similar to a previous event (Foley et al., 2011). Spectroscopic observations by Smith & Mauerhan (2012, ATel#4412) on Sept. 15 & 16 exhibited very broad lines strongly suggesting that SN 2009ip had become a real supernova. However, Margutti et al. (2012, ATel#4414) analyzed SWIFT UVOT observations from Sept. 20 and Sept 22 and found no clear evidence for a re-brightening and suggested that this result was inconsistent with evidence for an emerging supernova. Furthermore, based on observations from Sept. 11 & 24 Martin et al. (2012, ATel#4416) reported that SN2009ip was dimming and reddening at a rate that is inconsistent with a true supernova.

We obtained observations on SN 2009ip from Coral Towers Observatory 0.4m (CT) and New Mexico Skies 0.5m (NM) and find the following results:

Sept. 23.60 I=18.2+/-0.3 (CT) 
Sept. 24.57 I=16.6+/-0.3 (CT) 
Sept. 25.20 I=15.0+/-0.3 (NM) 
Sept. 25.52 I=15.6+/-0.3 (CT). 
The NM measurement is blended with a nearby source with mag R=17.7.

We find clear evidence that the source significantly brightened at red wavelengths over a period of ~46 hrs. The current brightness suggests that SN 2009ip has indeed become a supernova. The dimming observed by Martin et al. (2012) may be a sign of shocks interacting with shells of circumstellar material from previous outbursts.

We strongly encourage further follow-up in multiple photometric bands.