Daytime astrophotography from Macquarie Huntsman Telescope

Researchers at Macquarie University have developed a method for observing celestial bodies during daylight, enabling 24/7 satellite monitoring and significantly boosting Earth and space safety.

This approach utilizes the Huntsman Telescope at the university, an array of ten camera lenses operating simultaneously, originally intended for highly sensitive night sky observations.

Daytime astrophotography from Macquarie Huntsman Telescope: Multi-lens telescope supports stargazing in broad daylight

In a recent study published in the Publications of the Astronomical Society of Australia on May 20, the team demonstrated the Huntsman's precision in measuring stars, satellites, and other celestial objects, even when the sun is overhead, a challenging task for traditional astronomers.

"Observing stars and satellites in optical wavelengths during the day has been a centuries-old challenge. Our tests show that the Huntsman can achieve outstanding results during daylight," explained Sarah Caddy, the lead author and astrophysics Ph.D. candidate who was instrumental in designing and constructing the Huntsman Telescope.

Caddy, along with a team of Ph.D. students and staff at Macquarie, deployed the Huntsman, which officially opened at Siding Springs Observatory in Coonabarabran last year. The telescope features an array of 10 highly sensitive 400mm Canon lenses, each aligned to cover the same region of the sky.

Typically, daytime observation is hindered by the sun's overwhelming light, which drowns out other celestial objects. However, Caddy and her colleagues used special "broadband" filters on a prototype Huntsman telescope to block most daylight while allowing specific wavelengths from celestial bodies to pass through.

This prototype, a single-lens pathfinder installed at the university's observatory, enabled the team to refine settings in a controlled environment without impacting the main Huntsman telescope.

Photo Credit: Macquarie University

A night time view of Betelgeuse

The Huntsman’s capability for daytime observation allows continuous tracking of bright stars that might otherwise be unobservable for months due to their proximity to the sun. One notable example is Betelgeuse, a red supergiant star located about 650 light-years away in the Orion constellation.

Betelgeuse, which dimmed significantly between late 2019 and 2020 due to a major ejection of gas and dust, remains of great interest to astronomers. "Without this daytime mode, we'd be unaware if Betelgeuse had gone supernova until months after its explosive light reached Earth," noted Associate Professor Lee Spitler, Head of Space Projects at Macquarie's Australian Astronomical Optics.

Betelgeuse’s unpredictable behavior means it could go supernova anytime, and during four months of the year, it is only visible in the daytime due to the sun’s position.

Photo Credit: Macquarie University

Daytime view of Betelgeuse, about 650 light years away

Mastering daytime observation also advances space situational awareness (SSA), crucial for monitoring the increasing number of satellites, space debris, and other objects orbiting Earth. With the launch of tens of thousands of satellites anticipated in the next decade, there’s a pressing need for continuous day-and-night monitoring.

"With approximately 10,000 active satellites already orbiting Earth and plans for an additional 50,000 low Earth orbit satellites in the coming decade, a network of telescopes dedicated to continuous observation is essential," said Caddy. This capability can prevent potential collisions, which could disrupt communications, GPS, weather monitoring, and other vital infrastructure.

Satellite photometry, using optical telescopes to study changes in brightness, provides valuable information about the composition, age, and condition of satellites. Daytime observation enhances this by allowing the monitoring of satellite orientation in addition to their location.

Photo Credit: Macquarie University

Daytime astronomy

Caddy’s team showcased the Huntsman's potential for various astronomy observations needing continuous coverage, including satellite tracking. Over several months, the team used the mini-Huntsman to refine techniques, systematically examining factors like optimal exposure times and precise tracking through atmospheric turbulence.

"Daytime astronomy is an emerging field. With advances in camera sensors, filters, and other technologies, we've seen significant improvements in sensitivity and precision under bright-sky conditions," said Caddy.

Spitler added, "We've developed a methodology for daytime observation that can be implemented with affordable, high-end equipment like Canon lenses." The Huntsman’s ten lenses work in parallel, feeding into ultra-fast CMOS camera sensors that can capture thousands of short-exposure images per second, managed by a robotic control system for continuous monitoring.

"Accurate, round-the-clock observations eliminate longstanding restrictions on when astronomers can observe the skies. Daytime astronomy will become increasingly vital as we enter the next Space Age," concluded Spitler.

Sarah Caddy (pictured below) with the Huntsman Telescope

Photo Credit: Macquarie University