Supernova ( SN ) 2004et is the eighth historical SN in the nearby spiral galaxy NGC 6946 .
Here we report on early photometric and spectroscopic monitoring of this object .
SN 2004et is a Type II event , exhibiting a plateau in its light curves , but its spectral and color evolution appear to differ significantly from those of other , more normal Type II-plateau ( II-P ) SNe .
We have analyzed Canada-France-Hawaii Telescope ( CFHT ) images of the host galaxy taken prior to the SN explosion , identifying a candidate progenitor for the SN .
The star ’ s absolute magnitude and intrinsic color imply that it was a yellow , rather than red , supergiant star , with an estimated zero-age main sequence mass of 15 ^ { +5 } _ { -2 } M _ { \odot } .
Although this mass estimate is consistent with estimates and upper limits for the progenitors of other , more normal SNe II-P , the SN 2004et progenitor ’ s unusual color could further imply a pre-explosion evolutionary history analogous to , but less extreme than , that for the progenitors of the peculiar Type II-P SN 1987A or the Type IIb SN 1993J .
The identity of the progenitor candidate needs to be verified when the SN has significantly dimmed .