  SN 1961V, one of Zwicky's defining Type V supernovae (SN), was a peculiar
transient in NGC 1058 that has variously been categorized as either a true core
collapse SN leaving a black hole (BH) or neutron star (NS) remnant, or an
eruption of a luminous blue variable (LBV) star. The former case is suggested
by its association with a decaying non-thermal radio source, while the latter
is suggested by its peculiar transient light curve and its low initial
expansion velocities. The crucial difference is that the star survives a
transient eruption but not an SN. All stars identified as possible survivors
are significantly fainter, L_opt ~ 10^5 Lsun, than the L_opt ~ 3 10^6 Lsun
progenitor star at optical wavelengths. While this can be explained by dust
absorption in a shell of material ejected during the transient, the survivor
must then be present as a L_IR ~ 3 10^6 Lsun mid-infrared source. Using
archival Spitzer observations of the region, we show that such a luminous
mid-IR source is not present. The brightest source of dust emission is only
L_IR ~ 10^5 Lsun and does not correspond to the previously identified
candidates for the surviving star. The dust cannot be made sufficiently distant
and cold to avoid detection unless the ejection energy, mass and velocity
scales are those of a SN or greater. We conclude that SN 1961V was a peculiar,
but real, supernova. Its peculiarities are probably due to enhanced mass loss
just prior to the SN, followed by the interactions of the SN blast wave with
this ejecta. This adds to the evidence that there is a population of SN
progenitors that have major mass loss episodes shortly before core collapse.
The progenitor is a low metallicity, ~1/3 solar, high mass, M_ZAMS > 80 Msun,
star, which means either that BH formation can be accompanied by an SN or that
surprisingly high mass stars can form a NS.
