NSAS March Update: Investigations for a Dark Site, Farewell SOPHIA, Density Waves, Quaoar's rings and the 2023 Hunter Valley Star Party

By  NSAS President

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Hi David,

Welcome to the first NSAS Newsletter for 2023 and its great to be back after what has seemed to be a normal summer. I managed to escape for a 10 week holiday which was fantastic but am now looking forward to enjoying the coming few months of cooler weather and darker skies.

Whilst I was away I had an opportunity to visit a farm near Eugowra, where NSAS is investigating the establishment of a Dark Sky site. As mentioned in the notice that went out a few weeks ago the chosen site we are looking at can easily hold in excess of 200 cars, tents and telescope equipment. It is perfectly flat with 360 degree views of clear skies down to an altitude of less than 10 degrees. In a few weeks time, a group of 5 NSAS'ers (is that we call ourselves(?)) will visit the site for formal measurement and assessments for ongoing suitability. indicates a SQM score of 21.99 and the latest VIRS data indicates no detectable local light. We hope to confirm both these and measure the seeing conditions on the trip.


Above is a picture of the local landscape and a link to a short 360-degree video of the site is below.



It was really quite interesting and fun to set up my telescope with sheep literally 5m away from me. I managed to capture about 6 hours of NGC2997 (Spiral Galaxy in Antlia) and I'm reasonably pleased with it, although it was an 80% full moon for the nights I was there and the upload to MemberJungle seems to have played havoc with the colours but I'm pleased with the result none-the-less. Our next trip with other members of the society will be with the Moon only at 10% and hence a truer assessment of the night sky will be able to be made. 


Hopefully the trip proves successful, and the society can progress with a formal relationship with the property owners. 

Coming back to Sydney I was pleased to see the April edition of the Australian Sky and Telescope (don't forget discounts for NSAS members) magazine had arrived and there were a number of interesting articles to read. 

The first of these, I highly recommended is the story about the latest research on spiral arms in galaxies, how they form and how they may be better described as "density waves". A simple way to understand this concept is that the Sun travels around the Milky Way at 240 km/s, whereas the spiral arms only rotate at 210 km/s. This discrepancy means that our solar system moves in and out of the spiral waves over time. Given the multitude of stars and the gravity interacting between them creates "density waves". These more dense areas are "enough to ignite the formation of stars", however, these newly formed stars then move along with the star arms, and as we see in the case for our own Sun, can be at faster pace. This is a fascinating and well written article by Monica Young and contains several illustrations to make the information easy to absorb. 

The second of the articles of note is about the shutting down of SOFIA (Stratospheric Observatory For Infrared Astronomy) which you may recall is the 2.5m telescope installed into the fuselage of a 747 Jumbo Jet that would cruise up to 43,000' with SOFIA peering out the side at the InfraRed wavelengths. Fully operational in 2014, it was originally planned for 2001 and to last for 20 years but due to high annual operating costs (second only to Hubble) it has been decommissioned with the last flight occurring in September 2022. SOFIA wasn't the first aircraft based observatory that NASA has been involved with with Learjets and military transport plans preceding it, but it was certainly the most eye catching and inspiring of them all. SOFIA contributed to several major scientific achievements, but in the end, the volume of these compared to the operating expense spelt the end of this ambitious project. Again, this is another well written and researched article and Shannon Hall, its author, has captured the story well. 

From an authoring perspective, a big congratulation to Peter Nosworthy from NSAS is in order too. Peter is a member of NSAS and is part of a team of Australian astronomers who acquired data during occultation of Quaoar, a dwarf planet in our outer solar system. At only 1,110km wide it is a tiny object for something so far out in our solar system to be photographed. Congratulations Peter on your involvement where you captured data to contribute to the paper that was published in Nature. The co-authored paper "A dense ring of the trans-Neptunian object Quaoar outside its Roche limit" is an interesting read and the postulation of resonance poses an interesting problem to be solved.  

On a final note, the Committee has decided to proceed this year with the Hunter Valley Star Party. Negotiations are currently underway with several providers and further details will be provided as soon as we can. Pencil in (don't use ink yet) 17th - 20th August as the likely dates. Watch this space. 

I hope you are all keeping well and taking advantage of the numerous NSAS events that are on. These include events designed specifically to help beginners get going and provide "safe places" where no question is too silly to ask (Refer the Beginners Open Question nights on the website).

This month's speaker, Rami Alsaberi will be talking to us about Supernova remnants in the nearby Magellanic Clouds. The session will be broadcast on zoom so make sure you tune in. You can get a calendar reminder from HERE and it is Tuesday 21st March at 7:30pm. We will also be opening St Regis Hall and everyone is welcome to attend and join in the conversations afterwards. Free coffee and biscuits!! 

Objects for March 2023


I hope you are all enjoying the Clear Skies at the moment. Get out there and look up !

David Stevenson




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