M82 supernova observations

[Philip Benson]

I first imaged this supernova the day after its discovery after hearing the reports.   After imaging it over a couple of nights I decided it was a good time to dust off my Star Analyser filter and see if I could get a spectrum of the supernova.  

First step was to make sure it would fit into the filter wheel of my QSI camera.  That worked OK so I then fired off a couple of test exposures to make sure I could see the spectrum.  That also worked and with a 30sec exposure I could quite easily see one or two lines appearing in the spectrum.   Next I loaded up RSpec and used a known A0 type star (Alioth) as a calibration source. 

From that I was able to identify that a strong spectral line visible in the supernova spectrum had an observed wavelength of 6090 angstroms or thereabouts.  This was identified as ionised silicon which should have a lab wavelength of 6355 angstroms.  So the line in my spectrum was being noticeably blue shifted.

A quick application of the Doppler equation allowed me to calculate an approx. shell expansion velocity and this turned out to be in the order of 13,000km/s.   Correcting for the observed redshift of M82 which is quoted as 200km/sec gave me a final figure for the expansion of 13,200km/s or 29,700,000 mph!  That equates to 4.4% of the speed of light.

For anyone interested I can post some screenshots of my spectral profiles from RSpec.  

[Philip Benson]

My apologies...  Just realised I have posted this under the wrong discussion.   Please move as appropriate.