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Swift observation of SN2009ip

ATel #4414; R. Margutti, A. Soderberg, D. Milisavljevic (Harvard University)
on 24 Sep 2012; 09:19 UT
Credential Certification: Raffaella Margutti (rmargutti@cfa.harvard.edu)

Subjects: Ultra-Violet, X-ray, Supernovae, Transient

Referred to by ATel #: 4416, 4423, 4425, 4427, 4430, 4431, 4439, 4444

SN2009ip has been recently suggested to have transitioned from LBV-like eruption episodes to a real type-IIn supernova explosion (Smith, Atel#4412). A Swift ToO was executed starting from 2012-09-22T16:28:53 UT. We obtained Swift-UVOT observations in the 6 optical/UV filters. SN2009ip is well detected in all the 6 filters. Including possible contamination from the underlying host galaxy, we measure the following preliminary magnitudes (UVOT photometric system Breeveld et al. 2011, arXiv:1102.4717): v= 18.0 +\- 0.1; b= 18.1 +\- 0.1; u=17.9 +\- 0.1; w1= 19.1 +\- 0.1; w2= 20.1 +\- 0.1; m2= 20.1 +\- 0.2 Magnitudes are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.03 in the direction of the transient (Schlegel et al. 1998). When compared to Swift-UVOT observations acquired two days before (PI= Roming), we find no clear evidence for a re-brightening, which seems inconsistent with the suggested evidence for an emerging supernova. Contemporaneous Swift-XRT observations have been performed (total exposure of 6 ks). No X-ray source is detected at the optical position of the transient, with a 3 sigma upper limit of ~6.3d-3 cps in the 0.3-10 keV energy band. The Galactic neutral hydrogen column density in the direction of the event is 1.2d20 /cm2 (Kalberla 2005). Assuming a spectral photon index ~2, this translates into an absorbed flux of ~3d-13 erg/s/cm2 (corresponding to a luminosity of ~2d40 erg/s. A luminosity distance of 24 Mpc has been used). We thank the Swift team for scheduling these ToO observations.