2011 March 31

Part of the 365 Days project.

Sutherland, South Africa, looking towards the Milky Way.

Nikon D70
ISO1600
f3.5
18mm
48 seconds

The unfortunate pink glow in the top left corner is fogging due to the CCD in the camera getting warm during a long exposure.

Really I should have used a lower ISO for reduced noise, and a smaller aperture to resolve more detail, but I wanted to keep the exposure as short as possible to reduce “smudging” from the Earth’s rotation.

A five-minute exposure with star-trails is here.

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2011 March 29

Part of the 365 Days project.

Very hard dolerite rock resists weathering producing flat top “mesas” (flat tableland with steep edges), a familiar sight throughout the Karoo. The harder rocks weather more slowly, and so these hills are in effect held up from their tops, and only wear down as the softer rocks below undermine the harder layers. The plateau that the SAAO telescopes are on is such a dolerite sill.

In the distance is a very distinct flat-topped hill, called Tafelberg, which is also a remaining piece of a sill.

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2011 March 27

Part of the 365 Days project.

The rocky outcrop in the distance is Skuweklipkop (directly translated as “Rough Stone Hill”) but to the locals it is known as “Camel Rock” due to it’s humped shape.

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2011 March 26

Part of the 365 Days project.

Earthcache GC20ETY “Rock Stars”.

These unique rocks have formed in such a way that they ring like metal when hit. Wikipedia only lists five such sites worldwide.

When the intrusion of molten rock occurred, the liquid rock cooled so quickly that the crystals didn’t have time to grow large, with the result that the dolerite is (a) almost micro-crystalline and (b) almost uniform in constitution. This resembles a metallic structure. The rocks can vibrate coherently because there are no internal inhomogeneities to damp the sound waves.

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2011 March 25

Part of the 365 Days project.

The Southern African Large Telescope (SALT) is the largest single optical telescope in the southern hemisphere, with a hexagonal mirror array 11 metres across.

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2011 March 24

Part of the 365 Days project.

Dog clutch rebuilt and reinstalled from a “broken beyond repair” situation. Genius that I am. This clutch allows our mount to either track or slew in right-ascension.

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2011 March 23

Part of the 365 Days project.

New Peltier thermoelectric coolers installed in the left-hand scattering detector of our spectrometer at SAAO, Sutherland, South Africa.

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