First Scientific Results from IDSDC PlaneWave CDK700 Telescope

The Asteroid Belt resides between the orbits of Mars and Jupiter, and contains millions of small rocky and icy bodies thought to be left over from the formation of the Solar System 4.5 billion years ago.

When one of these dim, dark asteroids happens to pass in front of a star, if you are in the right place on Earth at the right time, you can see the star “wink out” for a moment as the asteroid blocks its light.  This type of event is called an “occultation”.   

A volunteer organization called the International Occultation Timing Association, or IOTA, provides predictions of where and when to observe one of these events.  Here is an example of a set of predictions for the IDSDC in Fountain Hills, covering about a week of time:

On May 2, 2026 at about 3:15 A.M. the shadow of a 5.6 mile diameter asteroid swept across Fountain Hills.

Ted Blank at the IDSDC recorded it in our new PlaneWave 27.5” telescope by taking 30 timestamped pictures per second of the star before, during and after the occultation.  Data from events like this can tell us a lot about the size and shape of an asteroid without needing to send a spacecraft to visit it.

The picture below shows how the shadow passed across Fountain Hills.

Click PLAY on the video below to watch the motion of the asteroid’s shadow as it crossed Fountain Hills. 

By carefully measuring the time of the disappearance and reappearance of the star behind the asteroid, we can measure the asteroid’s diameter with great accuracy.  Data from our recording is sent to the Minor Planet Center to be added to the library of information about this asteroid.

In the pictures below, you can see the star before the asteroid passed in front of it (left), and then during the occultation when it is almost invisible (right).  The star is located at the intersection of the two red lines.

Above you can see the star before the asteroid passed in front of it, and then during the occultation when it is almost invisible.

The graph below shows the amount of light from the star before, during, and after the occultation.  From a graph like this, scientists can obtain highly accurate knowledge of the asteroid’s size, shape, and orbit – information that might someday allow us to deflect an asteroid headed at Earth!

When multiple observers in different locations on Earth record different parts of the asteroid passing in front of the star, a profile of the asteroid can be obtained, which is more accurate than any Earth-based telescope can provide, as in this example:

And sometimes a lucky break can result in the discovery of a satellite (moon) of an asteroid!

For more information on asteroids, citizen science, and how you can contribute to our understanding of the history of the solar system, visit www.occultations.org or contact the author at tedblank@gmail.com.