How a BRIN Scientist Captures Star Trail at Timau National Observatory

TEMPO.CO, Jakarta - Thomas Djamaluddin, an astronomer and astrophysics researcher from the National Research and Innovation Agency (BRIN), has captured the star trail phenomenon under the night sky of Timau National Observatory in East Nusa Tenggara (NTT). How did he do it?

Through a 10-hour observation, Thomas recorded the star trail forming a circle around the south celestial pole with the background of the dome of the National Observatory Timau. The photography took place overnight from Thursday, June 18, 2026, at 07:00 p.m. local time to Friday at 05:00 a.m. local time.

The photograph was captured on a DSLR camera, and in practice, the camera recorded for about three hours.

The result, Thomas explained, showed a display of starlight forming concentric circles in the southern sky. "Not only is it visually stunning but also rich in scientific significance," as quoted from an article published on the BRIN page two days ago.

According to the Coordinator of the Astronomy and Observatory Research Group at the Space Research Center, the photography was not technically complicated, but it is rarely done since it requires very supportive weather conditions.

The sky must be clear throughout the night, and the observation site must have minimal light pollution and cloud cover.

"Photographing for 10 hours requires stable weather conditions all night long," said the research professor, also adding that such conditions are not always easy to obtain. "One of the best locations to do this is the Timau National Observatory, which has excellent night sky quality," said Thomas.

He explained that the main goal of the photography was not just to produce interesting pictures but to show one of the most basic astronomical phenomena, the rotation of the earth. Many people witness the sunrise and sunset every day without realizing that they occur because the earth rotates on its axis.

"The star trail shows the rarely noticed earth's rotation," said Thomas.

Thomas added that in photography directed to the north or south, star trails will appear in a circle. The circle is centered on the celestial pole, an imaginary point that extends the axis of the earth's rotation into space.

Since the Timau National Observatory is located in the southern hemisphere, the photographing is directed towards the southern sky, so the pattern of star movement appears to revolve around the south celestial pole of the sky. This geographical position, said Thomas, makes Timau an ideal location to document this phenomenon.

"The combination of dark sky and observatory location produces very interesting documentation," said Thomas.

Besides documenting earth's rotation, the photo also shows the relatively low light pollution of the night sky in Timau. This condition is one of the reasons why BRIN built the Timau National Observatory as a modern astronomical observation center in Indonesia.

But night alone is not enough. To produce clean images, the photography is done when the night is truly dark until just before dawn. This is to avoid satellite trails that reflect sunlight during dusk or dawn.

"There is a growing number of satellites in orbit, including communication satellite constellations like Starlink. Therefore, photography is done after dark and ended before dawn to avoid satellite trails from disturbing the photo results," he said.

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