SALT |

Astronomical twilight

Thea Koen — Wed, 23 Aug 2017 11:52:25 +0000

This is the time of day when the sun has either set or is about to rise, but the sky is still being lit by its rays. At SALT we start our evening shift at sunset, preparing for the night ahead, but we only start taking science observations at the end of evening twilight. There is approximately 1.5 hours between sunset and the start of the night. Our night then usually ends shortly after morning twilight begins. The telescope is closed and parked and we head to bed.

Astronomy vs Astrology

Thea Koen — Sun, 18 Sep 2016 17:39:45 +0000

This is one that people often seem to confuse, despite their being extremely different. Astronomy, simply put, is the study of objects in space – like stars, galaxies and planets. Astrology is the interpretation of how the movement of celestial bodies might affect the lives of people. When someone comments ”you’re very curious, you must Aquarius” – they’re talking about astrology. When someone says “lets get out the telescope and look at the moon” – that’s a reference to astronomy

Mirror alignment

Thea Koen — Fri, 05 Feb 2016 13:01:06 +0000

SALT has 91 mirrors that work together as ‘one’ 10 metre diameter mirror. Every evening ‘mirror alignments’ need to be done to make sure that all the segments create a uniform spherical surface. The mirror alignment is done using an instrument located in the “Center of Curvature Alignment System” (CCAS) tower. The structure and dome are rotated to face the tower and a laser shines down which indicates which segments need to be moved so that they are all perfectly aligned with their neighbours.

Mirrors

briehan-lombaard — Tue, 01 Dec 2015 12:57:08 +0000

Every week two mirrors are removed, cleaned and re-coated with aluminium. That way the whole array will be cleaned within a year. The mirror crew are so effective that they’ll sometimes do as many as six in a week.