But when remote sensors and cameras on some telescopes at the Siding Spring Observatory, near Coonabarabran, indicated a fire had reached the facility on Sunday evening, anxious astronomers did not know what to make of the information.

''We were seeing temperature readings and pictures, but not being experts on fires or how equipment melts, none of us knew how to interpret it,'' said astronomer Bryan Gaensler.

Rob McNaught's Telescope near Coonabarabran. Photo: Supplied

The Warrumbungle National Park fire started on Sunday, less than a week before the 10th anniversary of the fire that destroyed Canberra's Mount Stromlo Observatory, including the Great Melbourne Telescope.

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Now its replacement, the SkyMapper, faced an identical threat.

While Mount Stromlo scientists had to wait days to learn of the fire damage, advances in sensor technology and the introduction of Twitter meant Siding Spring astronomers could follow Sunday's disaster as pictures from webcams mounted on their telescopes showed buildings alight throughout the night.

''My overwhelming feeling was one of helplessness,'' said Professor Gaensler, from the University of Sydney, who tweeted fire updates.

By 10pm other staff tweeted pictures of the lodge, accommodation for visiting astronomers, on fire.

While the pictures suggested there would be significant damage, an early morning survey by staff and fire crews revealed that although the director's cottage, the visitors' centre and the lodge had been wholly or partially destroyed, the telescopes had survived.