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Betelgeuse, Rigel and Bellatrix

Image

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About this observation
Observer
Peter Tickner
Time of observation
20/02/2020 - 20:00
Object
Betelgeuse
Observing location
Urban Berkshire
Equipment
ZWO ASI071 MC Pro CMOS camera
14inch LX200 SCT at f/10
EQ8 mount
OAG with Lodestar X2 Autoguider
IR Cut filter

This isn't scientific, especially as I had an IR Cut filter on, but I wanted to compare the relative image sizes of Betelgeuse in its current dimming phase to Rigel and Bellatrix, as the brighter the object, the larger the area it occupies on the camera image.  Betelgeuse usually varies magnitude from 0 to 1.3, Rigel 0.17 to 0.22 and Bellatrix is 1.65. In the image Betelgeuse is in the centre and compared with  a negative image of Rigel (the dark red outer area) in size below and Bellatrix above (with Betelgeuse in negative blue).  This shows that Betelgeuse is currently much fainter than Rigel and only slightly brighter than Bellatrix.

No doubt there is a way to use the raw image data to measure actual brightness and I'd be happy to be shown how.

Peter

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