Hall's Harbour Observatory,   Hall's Harbour, NS

Webcam: camera #4

21-Nov-2017, 19:04 AST 21-Nov-2017, 23:04 UTC

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What am I looking at?

** Note that this system is still under construction. **

This camera provides an absolute azimuth readout for the dome. It monitors a binary-coded data strip around the circumference of the dome, allowing software to determine and update the actual position of the dome. This is used to keep the dome slot centred in front of the telescope in operation.

The binary coding consists of three bits, providing an accurate position to the nearest degree within an 8-degree block. The dome control software uses a tick counter to determine the dome azimuth independently. However, the counter is prone to fractional-degree errors which accumulate during a long session. Determining the actual position within an 8-degree block is sufficient to eliminate this accumulating error.

The data bits read from bottom to top, with a blank space to accommodate the guide rollers between the 2 bit and the 1 bit.

What's that piece of hardware above the mirror for? It is one of two storm tie-downs. While the dome is quite secure in strong winds, I can install turnbuckles on the tie-downs for extra security in hurricane-force winds.