If you could observe the remnants of the SN fromn a vantage point on or near the progenitor star, would you not be looking through a shell of rapidly expanding matter and gasses presenting emission lines, and would this create a redshift of ~12,000kms?
In reference to M101 and the Type 1a supernova SN 2011 fe.
Distances that I have found for M101 vary from 21 million light-years to 28 mly. The value for the measured redshift of M101 is 0.000804. Will the emissions from the supernova create any changes to the redshift measurement? And if so...