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X-ray emission at a position consistent with SN2009ip

ATel #4457; R. Margutti, A. Soderberg, (Harvard University)
on 6 Oct 2012; 23:12 UT
Credential Certification: Raffaella Margutti (rmargutti@cfa.harvard.edu)

Subjects: X-ray, Supernovae

Referred to by ATel #: 4499

We observed SN2009ip for a total of ~93 ks with Swift/XRT. We split the observation into two epochs. The first epoch comprises data acquired between September 10th and October 1st, for a total of ~53 ks of exposure. No source is detected at the position of the SN, with a 3 sigma upper limit of 3.3d-4 counts/sec in the 0.3-10 keV energy band (a similar limit has been reported by Campana Atel #4444). Assuming a power-law spectrum with photon index Gamma=2 and correcting for the Galactic neutral hydrogen column density in the direction of the SN (NH=1.2d20 cm-2, Kalberla et al., 2005), this translates into a flux limit F<1.2e-14 erg/s/cm2 (luminosity L< 8d38 erg/sec at the distance of 24 Mpc). The second epoch collects data taken after Oct 1st (total exposure of ~40 ks). A faint X-ray source is detected at a position consistent with the optical position of the SN, with count-rate of (9.7 +\- 2.2)d-4 counts/sec in the 0.3-10 keV energy band, corresponding to a flux F=(3.3 +\- 0.7)d-14 erg/s/cm2 (we assume a power-law spectrum with photon index Gamma=2 and correct for the Galactic neutral hydrogen absorption). At the distance of 24 Mpc, this corresponds to L= (2.3 +\- 0.5)d39 erg/sec. Further observations are planned to clarify the nature of this source, its possible association to SN2009ip, and to monitor its temporal evolution. We note however that the sudden appearance of X-rays at a position consistent with SN2009ip suggests a link with the SN explosion. We thank the Swift team for scheduling these ToO observations.