Reply To: Supernova in M101 !

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Mr Ian David Sharp

What is the V filter I read on earlier?
I want to do photometry on this. Do you need a really high focal length telescope e.g. C11 or can you do it with smaller lower focal length refractors?
Can you use a h-alpha filter 7nm bandwidth and do useful photometry ? as I am in a light pollution area.

You can use smaller telescopes – I regularly use a 100mm refractor to measure stars down to 13th magnitude.

The V filter is a Johnson/Cousins V Filter. These are standard photometric filters. You can still work unfiltered or use a colour R, G or B filter as long as you specify which was used.

I don’t believe you would have much success with a narrowband filter.

Hope that helps