Betelgeuse measurement #Betelgeuse


ROD LEVENE
 

Hi folks.
I wanted to make use of our little bit of clear last night, so allowed first Betelgeuse and then Bellatrix to track across a telescope field for 10 sec. I did each 3 times.
The good old fashioned way to compare apparent magnitudes of stars is to measure the diam. of their image on a photographic negative.
I decided to do something similar, highly magnifying their tracks by an identical amount. I found that Betelgeuse track averaged around 16mm thickness whereas the Bellatrix track was 15mm. This means that Betelgeuse is still the brighter but only by a tiny degree. I intend to do something similar whenever I can over 2020.
One problem is the fact that we are comparing very different colours but I think I know the response curve of my sensor and it's pretty flat from orange to blue. A good aspect is that the two stars are near and at a similar altitude, so their background conditions are similar.
Considering that Stellarium gives Bellatrix an app. mag. of 1.6 and an average for Betelgeuse of 0.45, we currently have a quite a minimum in brightness. Betelgeuse' range is stated as 0.0 to 1.3, over a bit more than a 140 days on top of a longer 6 year period. Its current similarity to Bellatrix puts it more like 1.4 or 5 at the moment and this recent dimming only really got under way from around last October.
Most scientists agree however, that it won't go supernova just yet for a few thousand years.


Andrew West
 

Rod,
Have you made any allowance for Leeds's grossly light-polluted night skies?
Andy.


On Fri, 17 Jan 2020, 12:13 pm ROD LEVENE via Groups.Io, <rodlev=btinternet.com@groups.io> wrote:
Hi folks.
I wanted to make use of our little bit of clear last night, so allowed first Betelgeuse and then Bellatrix to track across a telescope field for 10 sec. I did each 3 times.
The good old fashioned way to compare apparent magnitudes of stars is to measure the diam. of their image on a photographic negative.
I decided to do something similar, highly magnifying their tracks by an identical amount. I found that Betelgeuse track averaged around 16mm thickness whereas the Bellatrix track was 15mm. This means that Betelgeuse is still the brighter but only by a tiny degree. I intend to do something similar whenever I can over 2020.
One problem is the fact that we are comparing very different colours but I think I know the response curve of my sensor and it's pretty flat from orange to blue. A good aspect is that the two stars are near and at a similar altitude, so their background conditions are similar.
Considering that Stellarium gives Bellatrix an app. mag. of 1.6 and an average for Betelgeuse of 0.45, we currently have a quite a minimum in brightness. Betelgeuse' range is stated as 0.0 to 1.3, over a bit more than a 140 days on top of a longer 6 year period. Its current similarity to Bellatrix puts it more like 1.4 or 5 at the moment and this recent dimming only really got under way from around last October.
Most scientists agree however, that it won't go supernova just yet for a few thousand years.


Ivor Trueman
 

Rod - have you tried any of the photometry software? i.e. AstroImageJ or MuniWin

Looking at some youtube tutorials, it looks interesting.

Cheers,
Ivor


Waldemar Falcone
 

Bravo Rod,

May I suggest a calibration method? To let the star trail in front of a photogaphic lens, then repeat the experiment for 1 stop  darker, 2, 3, etc
Each stop is 1/2 of the light i.e. 0.753 magnitudes. Then you'll have a graph of thickness vs magnitude. It doesn't get round the colour problem.
Vad
De: AstroLeeds@groups.io <AstroLeeds@groups.io> em nome de ROD LEVENE via Groups.Io <rodlev@...>
Enviado: sexta-feira, 17 de janeiro de 2020 12:12:53
Para: LAStroLeedsGroupio <astroleeds@groups.io>
Assunto: [AstroLeeds] Betelgeuse measurement
 
Hi folks.
I wanted to make use of our little bit of clear last night, so allowed first Betelgeuse and then Bellatrix to track across a telescope field for 10 sec. I did each 3 times.
The good old fashioned way to compare apparent magnitudes of stars is to measure the diam. of their image on a photographic negative.
I decided to do something similar, highly magnifying their tracks by an identical amount. I found that Betelgeuse track averaged around 16mm thickness whereas the Bellatrix track was 15mm. This means that Betelgeuse is still the brighter but only by a tiny degree. I intend to do something similar whenever I can over 2020.
One problem is the fact that we are comparing very different colours but I think I know the response curve of my sensor and it's pretty flat from orange to blue. A good aspect is that the two stars are near and at a similar altitude, so their background conditions are similar.
Considering that Stellarium gives Bellatrix an app. mag. of 1.6 and an average for Betelgeuse of 0.45, we currently have a quite a minimum in brightness. Betelgeuse' range is stated as 0.0 to 1.3, over a bit more than a 140 days on top of a longer 6 year period. Its current similarity to Bellatrix puts it more like 1.4 or 5 at the moment and this recent dimming only really got under way from around last October.
Most scientists agree however, that it won't go supernova just yet for a few thousand years.


ROD LEVENE
 

Bellatrix and Betelgeuse share the same area of sky, so hopefully, they are still comparable.
Rod.

On Friday, 17 January 2020, 13:12:01 GMT, Andrew West <snorkelbob2004@...> wrote:


Rod,
Have you made any allowance for Leeds's grossly light-polluted night skies?
Andy.


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