  The bright, nearby, recently discovered supernova SN2010jl is a member of the
rare class of relatively luminous Type~IIn events. Here we report archival HST
observations of its host galaxy UGC5189A taken roughly 10yr prior to explosion,
as well as early-time optical spectra of the SN. The HST images reveal a
bright, blue point source at the position of the SN, with an absolute magnitude
of -12.0 in the F300W filter. If it is not just a chance alignment, the source
at the SN position could be (1) a massive young (less than 6 Myr) star cluster
in which the SN resided, (2) a quiescent, luminous blue star with an apparent
temperature around 14,000K, (3) a star caught during a bright outburst akin to
those of LBVs, or (4) a combination of option 1 and options 2 or 3. Although we
cannot confidently choose between these possibilities with the present data,
any of them imply that the progenitor of SN2010jl had an initial mass above
30Msun. This reinforces mounting evidence that many SNe IIn result from very
massive stars, that massive stars can produce visible SNe without collapsing
quietly to black holes, and that massive stars can retain their H envelopes
until shortly before explosion. Standard stellar evolution models fail to
account for these observed properties.
