SN 2010jl is a superluminous Type IIN supernova with its absolute visual magnitude brighter than -20. It was discovered on 2010 November 3.5 (UT) in UGC 5189 at a distance 50 Mpc. UGC 5189 is a dwarf galaxy with metallicity 1/3rd that of solar. Hubble Space Telescope (HST) images of the site of the SN taken a decade before the SN indicate that, unless there is a chance coincidence of a bright star with the SN site, the progenitor star had an initial mass more than 30 solar mass.

We studied two epochs of Chandra-ACIS X-ray imaging spectroscopy of SN 2010jl, taken around two months and then a year after the explosion. SN 2010jl is one of the brightest core collapse supernova in X-ray bands with peak luminosity close to 1E+42 erg/s.

The absorption column density in the first spectrum is high (1E+24), more than three orders of magnitude higher than the Galactic absorption column, and we attribute it to absorption by circumstellar matter. In the second epoch observation, the column density has decreased by a factor of three, as expected for shock propagation in the circumstellar medium. This is the first time a direct evidence of X-ray absorption by circumstellar matter is seen, and first time the evolution of column density has been traced.

SN 2010jl is a special Type IIn SN because we have been able to catch it in X-rays early on with as sensitive an instrument as Chandra and trace the early X-ray evolution. We have observed it a few more times with Chandra, XMM and Swift-XRT and a larger publication on this work, including radio observations is underway.