Top research facility ... fire rages towards the Siding Spring Observatory.

Top research facility ... fire rages towards the Siding Spring Observatory. Photo: NSW Rural Fire Service

Canberran firefighters are taking advantage of the cooler weather by burning off near Tharwa this evening.

The ACT Rural Fire Service Tidbinbilla Brigade will be helping conduct a hazard reduction burn at “Miowera” on Tidbinbilla Road between 7pm and 11pm, bringing a number of tankers and crew to the scene.

One heavy tanker, one medium tanker, one command vehicle and eight brigade members will be on site to help reduce the fuel load across one to two hectares.

Fire damaged ... Siding Spring Observatory.

Fire damaged ... Siding Spring Observatory. Photo: NSW Rural Fire Service

The ACT Emergency Services Agency said there may be temporary smoke cover, adding that people with asthma or other chronic respiratory diseases should remain inside if they were likely to be affected.

The reduction burn comes as crews continue to tackle a number of fires across the border.

Firefighters were called to a blaze at Dicks Creek Road near Murrumbateman overnight, where flames burnt through around 30 hectares. The fire is now classified as under control.

Crews are also on the scene of the Cobbler Road fire near Yass, which is under control after burning through 13,974 hectares.

The Yarrabin fire near Cooma has burnt through a significant area, moving across 12,185 hectares since starting more than a week ago.

It is now being controlled by “direct attack” as crews prepare for deteriorating conditions, Fred Nichols from the Monaro Rural Fire Service said.

“Crews are placing special emphasis on directly attacking hot spots and live fire within the southern containment lines today in preparation for an increase in temperatures and north westerly winds expected Thursday and Friday,” he said.

“Because of the expected conditions further fall back lines on the east and south east are being looked at by planning in consultation with local landholders.”

There is no immediate danger, but Mr Nichols said people should be prepared if conditions worsen towards the end of the week.

“The potential threat to the community will remain for at least the next seven days and people need to remain vigilant and continue to be aware of the conditions in their area,” he said.

“There is a risk of falling trees in burnt areas and residents returning to properties are advised to take care.”

Meanwhile, an Australian National University spokeswoman said the Siding Spring Observatory would be closed for the next two weeks to enable a full assessment of the damage caused by the Wambelong Fire.

"The priority at this stage is the safety and wellbeing of staff and their families, a number of whom have lost their homes in the fire," she said.

A team, including Vice-Chancellor Professor Ian Young, Research School of Astronomy and Astrophysics director Professor Mathew Colless, and support staff including a staff counsellor, will travel to Coonabarabran tomorrow to meet affected staff and their families.

"The University is currently assessing the needs of affected staff and families. It is also looking into options for an emergency appeal for members of the ANU and wider community who wish to support affected staff and their families," the spokeswoman said.

Three other ANU staff - two of whom are also volunteer fire-fighters - arrived at the site yesterday.

At this stage, the university had determined that three buildings had been destroyed: the lodge, a cottage and a storage building and the visitors centre and two sheds had been badly damaged. Four appeared to have some smoke damage to their buildings, but there did not appear to be any catastrophic damage to the scientific facilities.

"The university has approximately $80 million of assets at Siding Spring Observatory, which are fully covered with an extensive insurance arrangement," she said.