TheSkySearchers

So I went out tonight and tried to capture a change in the brightness of Betelgeuse.

20240224.5 UT

Visual
First I did a naked eye visual comparison of
Betelgeuse [Mv 0.5]
Hadar, [Mv 0.61]
Procyon, [Mv 0.34]
Achernar. [Mv 0.46]
Aldebaran was behind trees.

Assessment:
To my naked eye, Betelgeuse [Mv 0.5] seemed to be between Achernar [Mv 0.46] and Hadar [Mv 0.61] and at lest than 0.1 mag difference, any difference in the stars brightness was indistinguishable to my eye.

In 2019, Betelgeuse was very noticeably fainter than it should be and easily detectable to the naked eye.

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Photometry
Then I captured exposures of: -
Betelgeuse [Mv 0.5]
Hadar, [Mv 0.61]
Procyon, [Mv 0.5]

using a fully manual 200mm f4 lens set to infinity with DSLR set to ISO100 1/8s

I may defocus and tape the focus and increase the exposure to 1/4s to even out the light field for future measurements.
The trick is to get the exposure of the stars somewhere in the middle of the grey scale. You definitely do not want the star saturated. By using such a short exposure, I can use a camera and tripod only. No tracking mount required.

I then used Lightroom to read RGB levels and I reduced the data. This is a crude but effective method of photographic photometry demonstrated by the linear regression of the brightness between the three stars that span only 0.15 mag. If Betelgeuse was not on it's nominal brightness, the point for Betelgeuse would not form a linear regression line with the other points. So for now, no change in brightness. The strange brightness numbers are because I converted the logarithmic base 2.512 magnitude measurements to a linear scale.

Joe Cali

Good experiment Joe.

Will you be doing periodic tests?

Graeme

Graeme1858 wrote: ↑Sat Feb 24, 2024 3:04 pm Good experiment Joe.

Will you be doing periodic tests?

Graeme

Hi Graeme,
Yes, weather permitting. Because the stars are so bright, this can be done in almost any light pollution or level of moonlight.
cheers
Joe

Very interesting idea Joe and certainly worthy of today's VROD. You have coupled real science with naked eye observing! (And photometry)

Congratulations on the VROD!

helicon wrote: ↑Sun Feb 25, 2024 3:14 pm Very interesting idea Joe and certainly worthy of today's VROD. You have coupled real science with naked eye observing! (And photometry)

Many thanks Michael [@helicon]. I'll persevere with this project. If there is another dimming event in progress, I'll see if I can produce a light curve.

I wrote to my contact in the IRA, [Irish Republic of Astronomy] for his information sources. All he quoted was that it came from the President of the Irish Association of Astronomy.

Joe

Congratulations on the VROD for a very interesting project.