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How Faint Have You Seen Betelguese??

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#1 Cepheus Elf

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Posted 31 January 2013 - 04:13 PM

I've been watching the sky for not far off forty years now and every winter when Orion stands high in the sky I always check on the brightness of Betelgeuse just to see if it's brightened or faded a little from the previous year. I've read it can get as faint as mag. 1.2 or so which would make it fainter than Aldebaran! The dimmest I have ever estimated it is around 0.8 which admittedly was a very rough naked eye estimate!!. How faint have you seen Betelgeuse?

#2 brianb11213



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Posted 01 February 2013 - 03:23 AM

These very bright red stars are very difficult to estimate visually, differential atmospheric absorbtion has a significant effect and Purkinje Effect runs riot.

Aldebaran is as good a comparison as any; the colour index is similar and, at least at some times of the year, Betelgeuse and Aldebaran are reasonably high and at a similar altitude. But I can't remember ever seeing Betelgeuse as faint as Aldebaran; sometimes only 0.2 mag brighter (say 0.7 visual) but sometimes more than 0.5 mag brighter. Some years (but not recently) it has appeared brighter than Rigel to me, but given the large discrepancy in colour and altitude I would not like to turn this into a magnitude estimate.

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