Blaze Star Observing Challenge and Special Observing Award (2024)

T Coronae Borealis (T CrB) is known as the "Blaze Star" for its specular outbursts that tend to occur every eighty years. T CrB is a binary system that consists of a red giant star and white dwarf. Over time, the white dwarf accumulates hydrogen gas from the red giant. When the amount of gas exceeds a critical limit, the result is a powerful thermonuclear reaction on the surface of the white dwarf. The resulting eruption increases the system's brightness by a factor of 1,600 (8 magnitudes). These eruptions appear to occur every 80 years or so, the last being in 1946.

Astronomers predict that the Blaze Star's next eruption will happen sometime between now and September, becoming a 2nd magnitude star overnight!

The Blaze Star is in perfect position to observe in the evening sky during summer months.

Requirements to receive the Astronomical League's Special Observing Award

Observers who make two observations of T Coronae Borealis are eligible to receive the Special Observing Award, with two requirements:

    1. The first observation must be before the outburst, and the second observation must be after the outburst, when the star is bright;
    2. Share your observations in the Blaze Star Discussion Forum on the AAC home page.

In addition to the above, observers who submit observations to the American Association of Variable Star Observers (AAVSO) may receive an attractive pin from the Astronomical League. More about that at the bottom of this page.

Full details of the T Coronae Borealis Observing Challenge are here:

Alachua Astronomy Club Points of Contact

Observing Challenge Coordinator: Andy Howell (

Astronomical League Coordinator: Jerry Cheney (

All Observers

Observers without GO-TO Telescopes

  • Begin by centering epsilon (ε) Coronae Borealis in the eyepiece. Use your widest angle eyepiece.
  • Try to match stars you see through the eyepiece with the star chart. Then "star hop" to bring the Blaze Star, T CrB into the field of view.

Observers with GO-TO Telescopes

  • Use the hand control to aim the telescope at the galaxy IC 4587. This will put the Blaze Star close to the center of the telescope's field of view. (The galaxy will be too faint to see.)
Make Your Observation

After locating the star field, use comparison stars to estimate the Blaze Star's brightness.

  • The binocular & telescope finding charts (scroll down) omit the decimal point. For example, 106 is magnitude 10.6.
  • The smaller the magnitude, the brighter the star! So a 9.0 star is brighter than a 10.0 star.

EXAMPLE: If the Blaze Star looks half-way between the 99 star and the 106 star, your observation could be 10.2 or 10.3.

  • If the Blaze Star is too faint to see, what is the faintest star you CAN see?

EXAMPLE: If 99 is the faintest, your observation would be <9.9.


You may estimate the Blaze Star's brightness from visual inspection of a digital image.

(Advanced) Analyze the FITS image using software like Pixinsight, LesvePhotometry, or AIP4WIN. Use the G channel of of a color image or an image taken using a photometric V filter and a monochrome camera.

Share your Observation

Share your observations in the Blaze Star Discussion Forum on the AAC home page. Please include name, date & time, observing location, your estimate of the star's brightness (magnitude), and how you made the observation.

The Blaze Star (T Coronae Borealis) is a Recurrent Nova

This variable star normally sits at magnitude 10 (invisible to the unaided eye) in the constellation Northern Crown. Every eighty years or so, the star blazes forth in an outburst that increases its brightness by a factor of 1,600 times. When this happens, the Blaze Star shines at magnitude 2, making it equally bright as α CrB (Alphecca). Peak brightness lasts just a few days, so it's important to check the sky every clear night this summer to make sure the eruption is not missed.

The so-called "pre-eruption dip" has been a precursor to eruptions in the past. Because the most recent dip occurred in March, 2023, astronomers expect that the Blaze Star is poised for an outburst sometime between now and September 2024.

The purple line shows the predicted outburst this year (2024).

SOURCE: Dr. Brad Schaeffer, Louisiana State University. A special webinar presentation by Dr. Schaeffer is available here.

Corona Borealis - Home of the Blaze Star (T CrB)

The constellation Corona Borealis (Northern Crown) is a small constellation with a distincitive U-shaped pattern of seven stars that ancient observers visualized as a crown. The Blaze Star T CrB sits in a corner of the constellation about 1 degree from the 4th magnitude star Epsilon (ε) CrB. High in the sky during summer months, it is relatively easy to find, especially with the aid of binoculars.

MAP SOURCE: p. 53 of Sky & Telescope's Pocket Sky Atlas (Jumbo Edition), available for purchase here.

Binocular Finding Chart

Use with binoculars or the unaided eye. The field of view is 15 degrees. The open circle with cross hairs at chart center is the location of the Blaze Star, T CrB. Comparison star magnitudes are indicated without a decimal point, e.g., the star marked 22 is magnitude 2.2.

The seven brighter stars that form the asterism of the Northern Crown are in the upper right quadrant of the chart.

Click to download a full-size chart.

Telescope Finding Chart

Use this chart with 2 inch and larger telescopes. The field of view is 2 degrees. The open circle with cross hairs at chart center is the location of the Blaze Star, T CrB. Comparison star magnitudes are indicated without a decimal point. For example, the star labeled 99 is magnitude 9.9.

HINT: Point your telescope first at the star labeled 42, which is Epsilon Coronae Borealis (ε CrB). Use a low power eyepiece. Then rotate the chart until you are able to match stars visible in the eyepiece with stars shown on the chart. Finally, star hop your way to T CrB at the chart's center.

Click to download a full-size chart.

Star Diagonals: Alert!

A star diagonal reverses the image, just like a mirror (which it is).

If you are using a star diagonal, you most likely will have to use a REVERSED finding chart (below). The field of view is 2 degrees.

Click to download a full-size chart.

Upload Observations to the AAVSO (Optional)

As an added incentive, submitting your Blaze Star (T CrB) observations to the American Association of Variable Star Observers (AAVSO) qualifies you to receive a Special Observing Award pin from the Astronomical League.

The AAVSO is an independent research organization headquartered in Cambridge, Massachusetts. Founded in 1911 at Harvard College Observatory, the AAVSO became independent in 1955. Led by a professional astronomer, the AAVSO has observing sections that specialize in all facets of variable star observing. To submit your observations to the AAVSO:

  • Register for an account with the AAVSO (;
  • Request your observer code;
  • Upload observations to the AAVSO using the WebObs interface.

See your observations in the online light curve and how they compare to other observers! Congratulations on your contribution to science!

AAVSO's Observing Sections

June 18, 2024 Member's Corner Slide Presentation

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