Astrophysical Data

Betelgeuse - AAVSO Star of the Month - Feb 2020

Betelgeuse (Wikipedia)

Betelgeuse - AAVSO Chart


This page tracks the brightness changes of alpha Orionis (Betelgeuse), one of the most famous stars in the night sky. Betelgeuse is a red supergiant that forms the upper left shoulder of the constellation Orion. Betelgeuse is a variable star that changes brightness in unpredictable ways.

In early 2020, Betelguese is fainter than it has been in decades. Will it continue fading? Will it explode as a supernova? What exactly happens to a supergiant star as it nears the end of its life? No one knows what will happen next.  

OBSERVATIONS ARE NEEDED! All that's needed to participate are the unaided eye and the chart of comparison stars at the bottom of this page.

Reminder: Fainter stars have BIGGER magnitude values. For example, a star of magnitude 1.9 is FAINTER than a star of magnitude 1.7. 

Email observations to He will post results in the table below. When there are several weeks of observations, it will be possible to post a light curve (brightness versus time).

Date   Time (local) Magnitude Estimate Comparison Stars Used Observer  Remarks 
20 Jan 2020  9:42 pm  1.72  1.2, 1.7, 1.9, 2.1  H. Cohen

ensemble photometry from G channel of 35mm DSLR camera.

 12 Feb 2020  8.05 pm  1.8  1.7, 1.9  A. Howell Betelgeuse appeared fainter than the star labeled 17, but brighter than the star labeled 19.
 13 Feb 2020  8:52 pm  1.7  1.7, 1.9  A. Howell   By tilting my head so that Betelguese and comp star 17 are on the same level, the two stars appeared about equal.
 14 Feb 2020  8:48 pm  1.8  1.7, 1.9  A. Howell  Betelgeuse is intermediate in brightness relative to comparison stars 17 and 19, perhaps somewhat closer to 19 than 17. Estimate at 1.8.
 15 Feb 2020  7:15 pm  1.6  1.2, 1.7  A. Howell  Betelgeuse appeared distinctly brighter than the 1.7 comp star but definitely dimmer than 1.2. Estimate at 1.6. Assisted by Terry S.
 21 Feb 2020  9:10 pm  1.5  1.2, 1.7, 1.9  A. Howell  Step size between 1.7 and 1.9 looks about equal to the step size between 1.7 and Betelgeuse. Betelgeuse is significantly dimmer than Pollux, which is magnitude 1.2. Betelgeuse is about V mag 1.6 or 1.5, say 1.5 for tonight.
 22 Feb 2020  11:55 pm  1.7  1.2, 1.7, 1.9 A. Howell  As Orion is setting, the 1.7 comp star and Betelgeuse are horizontal in the line of sight and of nearly equal brightness. Much fainter than 1.2 and brighter than 1.9.
 26 Feb 2020  10:24 pm  1.6  1.2, 1.7  A. Howell  perceptibly brighter than 1.7 but significantly dimmer than 1.2
 14 Mar 2020  10:03 pm  1.5  1.2, 1.7  A. Howell  Somewhat closer to 1.7 in brightness than 1.2 (Pollux).
 27 Mar 2020  10:15 pm  0.9  0.9, 1.2  A. Howell  Brighter than 1.2 (Pollux), about the same brightness as 0.9 (Aldebaran).

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