Category Archives: Observatories

Visit to Siding Spring Observatory

One of the highlights of OzSky was a visit to Siding Spring Observatory, the home of the Anglo-Australian Telescope, the UK Schmidt Telescope and the Uppsala Telescope, among others. As an amateur, it’s always interesting to visit these big professional observatories, see the big telescopes and something of the work that goes on there.


Siding Spring Observatory, located on the peak of Siding Spring Mountain – Mt. Woorut in the local Aboriginal language – is run by the Australian National University and was opened in 1964. There are a number of telescopes on the site, including the 3.9 metre Anglo-Australian Telescope, the 1.2 metre UK Schmidt Telescope, the ANU 2.3m Telescope, the ANU SkyMapper, the 0.5m Uppsala Telescope, and Faulkes South among others.

As a group, we were getting a behind-the-scenes visit to the AAT and, because of the large group, we were divided into two smaller groups. One group went to the AAT first, while the second group (the one I was in) went up the mountain to look at the other domes.

I took as many photos of the observatory telescope buildings as I could; the information I’ve added with each one is largely taken from the Australian National Observatory’s visitor information leaflet ‘The Telescopes of Siding Spring Observatory’, which is available in the visitor centre.

The Anglo-Australian Telescope dome. The AAT was opened by Prince Charles in 1974 and is a joint operation between the UK and Australia and run by the Australian National Observatory (AAO). One if its roles is to hunt for planets around other stars. It also did the Galaxy Red Shift Survey.



The ANU 2.3 metre is in the box-like building – the story is that the ANU wanted a new observatory building and were told they couldn’t have one but they could have a new office building instead. They built this ‘office block’ which houses the 2.3 metre telescope!

ANU 2.3

Faulkes South was designed and built in the UK. Run by the Los Cumbres Observatory Global Network, it’s a 2 metre Ritchey-Chrétien telescope which is used for research and education.

Faulkes South

ANU SkyMapper. This is an automated telescope which is used for southern sky surveys, looking for trans Neptunian objects, supernovae, comets, NEOs and planets around other stars.


Solaris – built by the Polish Academy of Sciences, this 20″ Ritchey-Chrétien telescope uses photometry to look for planets around eclipsing binary stars.


UK Schmidt – operated by the AAO, this is a 1.2 metre survey telescope which has a wide field of view and is currently used to measure radial velocities of stars in our galaxy. Well known professional astronomer David Malin also used it to take detailed photos of southern sky objects.

UK Schmidt

Uppsala Telescope

Uppsala Telescope

One we’d walked back down to the visitors’ centre, it was time to go to the AAT dome. We were met by one of the staff, Chris, who gave us a guided tour. As with the ATCA visit, hard hats had to be worn (I did manage to avoid hitting my head this time!) inside the dome itself.
First, we saw the huge shipping crate the AAT’s mirror had been sent to Australia in. The 154″ mirror had been made by Grubb Parsons of Newcastle, England and shipped to Australia. Incidentally, the ‘Parsons’ of Grubb Parsons was Sir Charles Parsons, the inventor of the steam turbine engine which was used in many famous ships such as HMS Dreadnaught, Mauretania, Lusitania, Queen Mary, United States, etc. Turbines are still used today, although generally these are gas turbines used in some passenger ships and warships.

AAT Mirror crate

Inside the building we took the lifts up to the dome level and donned hard hats. First up was the control room; we didn’t know if we could get in there but the duty astronomer was happy for us to take a look.

AAT Control Room

From there, we went into the dome itself to look at the AAT.

The photo below shows a model of the AAT with the real thing behind it.


The back of the telescope and the horseshoe mount. The AAT had been lowered because it was in maintenance mode and the needed to do some work on the top end; luckily for us it meant they needed to move it while we were there.

The video shows the telescope and dome being moved, it starts off slightly out of focus but does sharpen up. As with the still photos I used my Canon 6D and 24-105mm lens but even with a full-frame camera I couldn’t fit it all in, even at the 24mm end.


The top end and upper cage.


Looking down the business end into the primary mirror. Attempts at selfies – which we all tried – weren’t that successful as it’s actually quite hard to get yourself in the mirror and take a photo!AAT

We went outside on to the dome catwalk. The view from there was fabulous, very scenic. It is, however, not for those with a fear of heights – you are, of course, perfectly safe but it is a long way down.

It's a long way down

The view from the top is fabulous with vistas across the Warrumbungles and beyond, as far as the eye could see. The evidence of the fires in January 2013 was plain to see, with blackened trees everywhere. The fire had come very close to destroying the observatory – it came right up to the AAT’s dome at one point – and they were very fortunate that there was little damage to the observatory itself, although the astronomers’ lodge was burned down and one astronomer, Rob McNaught, lost his house. One of the support staff at the AAT told us of how he escaped the fire; he had a very narrow escape because he took his motorbike, leaving his car on the mountain (his car survived), but by the time he realised he should have taken the car it was too late to turn back. As he said, he was very lucky.

The area is beginning to regenerate but there are some trees which won’t recover, simply because they are either too young and small or because they are on the upper slopes where the heat was more intense. Wildlife died, with the local koala population all but wiped out and kangaroos and emus decimated; domestic animals died and people lost homes. All this because of a couple of moron campers in the nearby Wambelong area who started a camp fire despite all the warning signs and being told not to.
In the first photo below, I think the green bit at centre is the Wambelong camping area where the disaster began.

View from the AAT dome View from AAT domeWe walked right round the outside of the dome before returning inside. From there we went down to the aluminising room where, once a year, the AAT primary mirror is recoated with a fresh layer of aluminium. As our guide said, if the mirror had to be removed for cleaning once a year, it may as well be recoated instead.
The 16 tonne mirror is removed from the telescope and lowered through a trap door down into the vacuum chamber, which is a task that has to be done with great care; if the mirror was damaged in any way, that would mean the end of the AAT’s life which would be tragic indeed.

Door through which mirror is lowered

Vacuum chamber  Notice on side of vacuum chamber

That was the end of the visit, which was very interesting. I’d always wanted to visit Siding Spring, which I didn’t do last time I was in the area, but the OzSky group got a great behind the scenes look at how one of the world’s biggest observatories operates. For me the highlight was watching the dome and the AAT moving, which wasn’t done to show off to visitors but just great timing on our part, showing up when they were moving the equipment to work on it.

Thanks to Donna Burton and her husband Chris (our guide) and the OzSky organisers as well as the staff at the AAT.

The Australia Telescope Compact Array at Narrabri


While at OzSky most of us made the 90 minute drive to the town of Narrabri and the Australia Telescope Compact Array (ATCA), located outside the town at the Paul Wild Observatory. This is run by CSIRO (the Commonwealth Scientific and Industrial Research Organisation), along with facilities at Parkes (this was featured in the film ‘The Dish’), Coonabarabran (the Mopra Radio Telescope, just down the road from Siding Spring) and the Australian Square Kilometre Array Pathfinder, another radio telescope, out in Western Australia.
ATCA operates all year round, 24 hours a day, no matter what the weather is doing, as radio signals can be gathered all day – unlike optical telescopes which need a clear dark sky in order to gather data. The dishes use interferometry, which allows smaller telescopes to work together and act as a much larger instrument, meaning the telescope can see very fine detail. Several times a year, the Array will be used with other radio telescopes across Australia to observe very, very fine detail.
For larger, ‘fluffy’, objects the telescopes are moved closer together, for smaller ones they are moved further apart.

As you approach the observatory, signs ask you to turn off electronic devices such as cellphones and radio transmitters, because these will interfere with the observations being made; unlike optical telescopes, radio telescopes are making observations day and night and are vulnerable to radio and electrical interference, in the same way that optical telescopes are compromised by light pollution. WIFI will also interfere with the telescopes’ operation, so all iPads, iPods and similar devices were also turned off.


The group was split into two, because there is not much room in the dishes to accommodate large groups, so those of us in group two looked round the exhibition, which explained radio astronomy, before our turn to go up into one of the dishes.

Outside the exhibition was a small radio telescope which visitors could aim at the Sun; doing this produced a crackling noise which was solar activity translated into sound; the stronger the activity, the louder the hiss.narrabri8 narrabri9

Another solar radio telescope was nearby, this was used to study the Sun between 1966 and 1984.




There was a lot of information explaining how radio astronomy works which, to someone like me, who has never really got into the subject, was interesting and informative.

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Australia has some of the most venomous species on the planet, so there was a warning sign up on the door of the visitor centre telling the unwary to watch out for snakes and what to do in the event of getting bitten. I was rather disappointed because, of three visits to Australia over the years, I have not seen one snake (I did see a large huntsman spider and an even larger Golden Orb spider though, which I could have done without; I hate spiders); I don’t want too close a view but I’d like to see at least one! I did see snake tracks at the Sandstone Caves near Coonabarabran, though. Next time…

The array consists of six telescopes, five of which can be moved along a 3 kilometre railway-style track. The sixth dish is located 3 km west of the end of the main track. Each dish weighs 270 tonnes, about the same as a fully-loaded Boeing 747, and each is 22 metres wide.


On this day, telescope 4 was the nearest, so this was the one we visited. We had to don hard hats (just as well because – entirely typically – I hit my head!) and wear closed-toe footwear to go up onto the dish. We climbed several sets of stairs to the top and into a tiny room just under the dish itself where we could see the feedhorns and the receiver.

Antenna 4


From there we climbed out onto the dish itself; the photo below shows the subreflector at the very top, while the next three photos show the feedhorns and the receiver. The subreflector picks up the radio waves reflected from the dish surface and focuses them into the feedhorn which, in turn, converts them into electrical signals.
Each telescope has a set of different feedhorns, only one of which is used at a time, and each feedhorn is designed to pick up radio waves of certain lengths. The largest feedhorn collects 20cm waves while the smallest collects 3mm waves.
From the feedhorn, the receivers collect the signals and amplify them millions of times.



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The view from Antenna 4. Note the huge puddles, the area had a lot of rain prior to our visit. NB, this doesn’t affect observations because a radio telescope can operate in all weathers.

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After we left the antenna we had a look at the control room, located in a building across a paddock from the visitor centre before heading back to the motel, via Narrabri for something to eat, arriving back in the early evening just in time to get ready for the night’s observing.

I can’t claim to have remembered some of the more technical information we were given during our visit, so I raided ATCA’s web page for information about how the system actually works. For more, see their site here and, also, go to their live page to see what the antennas are up to right now.


Sydney Observatory

While in Sydney, prior to OzSky, I visited Sydney Observatory, a small observatory built in 1858 and Australia’s oldest observatory. Located just up a hill from The Rocks (a bit of a chore to walk up it in 30° C heat!), during the 19th and early 20th centuries it was important to astronomy, shipping, meteorology and time-keeping but these days it is a museum. It’s also used for public outreach and public stargazing (although how much they can see through Sydney’s light-pollution is anyone’s guess).

Here are a few photos from the visit. I did mean to go back and join a guided tour but never got round to it so that’s something for next time. Some of the photos are noisy because my 6D doesn’t have a flash and I had to use ISO 10,000 for a few of them.

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The Transit Circle telescope


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The 29-cm Lens Telescope

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Matthew Flinders’ bearing book and a sextant similar to the one he would have used. Flinders charted the coastline of Australia and is also, at least partly, responsible for the name ‘Australia’.

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The observatory also has a display about transits of Venus, to coincide with the 2012 Transit. Unfortunately for us in the UK, the 2012 Transit was only visible at sunrise here, as the Transit ended, and we were clouded out anyway (the weather in summer 2012 was vile) although I had seen the 2004 Transit which was well-placed for us and, then, the weather co-operated.

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The object on display below is the Apollo feedhorn from the Parkes radio telescope. I didn’t get to visit Parkes on this trip, as it is a 6-hour round trip from Coonabarabran, which is a bit of a tall order to do in a day, but did go to the radio telescope facility at Narrabri, which will be in the next post.

Parkes Telescope Apollo Feedhorn

Sydney Observatory is a pleasant and interesting place to spend an hour or two, as is the allied Powerhouse Museum (near Darling Harbour) which also has some space-related stuff. If you’re in the area, go and take a look, it’s open from 1000 to 1700 every day, except Good Friday, Christmas Day and Boxing Day.