SN2011ht has been described both as a true supernova and as an impostor .
In this paper , we conclude that it does not match some basic expectations for a core-collapse event .
We discuss SN2011ht ’ s spectral evolution from a hot dense wind to a cool dense wind , followed by the post-plateau appearance of a faster low density wind during a rapid decline in luminosity .
We identify a slow dense wind expanding at only 500–600 km s ^ { -1 } , present throughout the eruption .
A faster wind speed V \sim 900 km s ^ { -1 } occurred in a second phase of the outburst .
There is no direct or significant evidence for any flow speed above 1000 km s ^ { -1 } ; the broad asymmetric wings of Balmer emission lines in the hot wind phase were due to Thomson scattering , not bulk motion .
We estimate a mass loss rate of order 0.05 M _ { \odot } y ^ { -1 } during the hot dense wind phase of the event .
The same calculations present difficulties for a hypothetical unseen SN blast wave .
There is no evidence that the kinetic energy greatly exceeded the luminous energy , roughly 3 \times 10 ^ { 49 } ergs ; so the radiative plus kinetic energy was small compared to a typical SN . We suggest that SN2011ht may have been a giant eruption driven by super-Eddington radiation pressure , perhaps beginning a few months before the discovery .
A strongly non-spherical SN might also account for the data , at the cost of more free parameters .