Indonesia to Observe 2026 Asteroid Occultation: Call for Collaboration

A rare astronomical event – the occultation of a star by the asteroid Strenua – is expected to be visible across parts of Indonesia and Australia on April 26, 2026. This phenomenon, where an asteroid passes between Earth and a distant star, causing a temporary dimming of the star’s light, is drawing significant attention from astronomers and amateur skywatchers alike. Understanding asteroids and their trajectories is a key component of planetary science and helps refine our understanding of the solar system.

To prepare for the observation of this event, the Bosscha Observatory held a colloquium on March 14, 2026, focusing on the potential for collaboration among institutions and observers. The discussion centered on maximizing the scientific value of the occultation by coordinating observation efforts, particularly within the narrow path of the asteroid’s shadow. A follow-up report on the colloquium was published on March 20, 2026.

During an occultation, an asteroid moves in front of a star, briefly blocking its light. This creates a measurable change in brightness, forming what astronomers call a “light curve.” Analyzing these light curves allows scientists to estimate the asteroid’s diameter, shape, and orbital path with greater precision. The data likewise contributes to a more comprehensive database of near-Earth objects.

“The more observation points involved, the more accurate the information that can be obtained,” explained Agus Triono, a researcher at the Bosscha Observatory. The observatory is actively encouraging collaboration with astronomy communities, observatories, and skywatchers throughout Indonesia, especially those located along the predicted path of the asteroid’s shadow.

The upcoming occultation will involve asteroid Strenua passing in front of the star HIP 35933, causing a temporary dimming of the star’s light for a few seconds. The predicted path of observation stretches across several Indonesian islands, including Sumatra, Java, Bali, West Nusa Tenggara, and East Nusa Tenggara, extending into Australia.

Researchers emphasize that occultation observations offer several advantages as an astronomical method. The technique can achieve high resolution, comparable to more advanced observation methods, and is relatively unaffected by light pollution. Observations can be made using smaller telescopes, broadening participation opportunities for institutions across Indonesia.

However, occultations are time-sensitive and occur along a specific path, limiting observational flexibility. The events are also very brief, requiring rapid photometric techniques – capturing as many images as possible within a short timeframe. Data from a single observation point is limited, necessitating simultaneous observations from multiple locations to gain a more complete understanding of the asteroid’s characteristics.

Due to limited existing data on asteroid Strenua, this observation is particularly valuable for improving the accuracy of information regarding its size, shape, and trajectory. The Bosscha Observatory hopes that through increased collaboration, the observation of this occultation will enrich research, exploration, and Indonesia’s contribution to global astronomy research.