SSO Update

Published in the RSAA Lunations
Vol1 Issue20 1–30 September 2021

The 2.3-meter Cassegrain Rotator is back

For alt-azimuth telescopes like the ANU 2.3-metre telescope, one has to control three axes simultaneously: altitude, azimuth, and a rotator. The rotator is used to compensate for field rotation as the telescope tracks across the sky. For WiFeS, this is done by a derotator, which compensates for field rotation using three flat mirrors. At the Cassegrain focus, a rotator is used to rotate the entire instrument as the field rotates.

With the decommissiong of CASPIR over a decade ago, the Cassegrain rotator had not been used for a long time and had ceased to work. With new instruments for the 2.3-metre being planned, we needed to investigate the functionality of the rotator. 

Much of the original supporting documentation was lost to the Stromlo fires in 2003, but very fortunately we were able to draw upon a few surviving drawings, photos and John Hart's familiarity with it all. This greatly assisted the SSO mechanical team in coming up with an approach for the removal and disassembly of the rotator. This involved manufacturing a few specialised tools and lifting attachments. Once removed to the bench in AAT workshop, it all started to work with quite minimal intervention, the underlying cause most likely being the grease that would ordinarily lubricate the large gears had  stagnated, separated out and caused stiction in the gear train, freezing it in place. It is hoped more regular use will prevent a similar situation recurring. The rotator has been mounted back on the telescope and is fully operational. 

_{Picture: Randal Darko gently nursing the Cassegrain rotator to a place where it could be inspected.} 

Science in the Pub and the Bok Lecture

Due to the lockdowns in the ACT and NSW, Science in the Pub and the Bok Lecture will be online events for the second year in a row. While it is disappointing that we cannot have the public visit the Observatory in person this year, we look forward to running these two online events. They were a great success last year with hundreds of people joining.

This year we have four outstanding speakers for Science in the Pub: Anna Moore, Karlie Noon, Fred Watson and Lisa Kewley. Lisa will also be giving the Bok Lecture. Please make a note of the following dates and times, come along, and invite your friends.

Science in the Pub: Friday, October 1st, 18:30 to 20:00

Bok Lecture: Saturday, October 2nd, 18:30 to 20:00

To register for the events, visit SSO’s StarFest page

Welcome Ethan Thirkell

Ethan Thirkell is the new electrical apprentice at SSO, Ethan has only just completed year 12 in 2020 so he is new to the electrical field but has always had an interest in the work related to the role. Ethan has recently left his position as a labourer with a local company that is focused on concreting and earthmoving to start his dream job as an electrician.   Ethan will be working under Daniel Bonello. We look forward to working with Ethan over the next four years.

A Visitor

One of the joys of working and living at the Observatory is the location. Here is a photo of a visitor peering into cottage #3 at SSO. It seems to be wondering why we are all working at home, or perhaps it is looking for a warmer spot to spend the day?

_{Picture: Kangaroo wanting to work in Cottage 3 with Mike}

Stay safe and stay well.

The team at SSO