Beatlejuice

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Baurice
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Beatlejuice

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Post by Baurice »


Not sure if this is the right place, so here goes:

I recently saw Betelguese outshining Capella! The last two nights I have re-checked it. Capella is very slightly brighter but, allowing for extinction and seeing how Capella, Rigel and Betelguese compare, I still end up with a brightness estimate of between 0.0 and 0.1.

I suspect that my eyes might be more red-sensitive than average, so has anyone else looked recently?

Even if I am 0.3 magnitude out, this still shows Betelguese as brighter than its normal range of 0.5 to 0.9. I have often suspected that the range is wider than that and we had the great fading not that long ago.
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Don Pensack United States of America
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Re: Beatlejuice

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Post by Don Pensack »


Except for the recent dimming, now past, Betelgeuse is a variable star with a 0.0 to 1.6 range.
Capella is more constant at 0.08
If Betelgeuse is at its brightest, you could not tell them apart
If you are observing in the evening now, , say around 9pm, Betelgeuse is much lower in the sky than Capella, so could appear slightly dimmer due to extinction.
So your seeing Capella as "very slightly brighter" is typical of Betelguese's magnitude range.
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Currently using a 12.5" dob and a 4" apo refractor
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Re: Beatlejuice

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Post by Baurice »


Don Pensack wrote: Mon Dec 19, 2022 6:13 pm Except for the recent dimming, now past, Betelgeuse is a variable star with a 0.0 to 1.6 range.
Capella is more constant at 0.08
If Betelgeuse is at its brightest, you could not tell them apart
If you are observing in the evening now, , say around 9pm, Betelgeuse is much lower in the sky than Capella, so could appear slightly dimmer due to extinction.
So your seeing Capella as "very slightly brighter" is typical of Betelguese's magnitude range.
Thanks, Don. The dimming effect, due to extinction, is very hard to estimate. I usually get some idea of it by comparing Rigel to Capella. With a magnitude difference of only 0.04, they should appear about equal. In February and March, Procyon comes into it, too. Extinction can be estimated by seeing the apparent brightness difference between it and Rigel. I have also seen Orion from many parts of the world, where Rigel is higher in the sky.

I've seen the range of Betelguese quoted as 0.5 to 0.9 but my experience suggests otherwise and is more in line with what you suggest. In fact, I even wonder if it can sometimes get even brighter than 0.0. If it appears as bright as Capella and the extinction factor is 0.2 of a magnitude, this suggests a magnitude of about -0.1 for Betelguese.

I've thought about photographing the area of sky but I think the Bayer matrix of a DSLR would lead to a false result.
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