Moving objects, and non-moving telescopes!

15 February 2013 by Fraser Clarke

Broken drive unit from the PWT

For those of you eagerly awaiting the next installment of comet ISON, I'm afraid all we have to report is a broken telescope! However, you can track a solar system body for yourself tonight (15th Feb 2013), as asteroid 2012-DA14 flies by the Earth at only 35,000km and should be visible in binoculars.

Last weekend, one of the drive units on the PWT telescope here in Oxford failed, and left us unable to move the telescope in Declination (basically, up & down). After a bit of testing, we've tracked the problem down to the motor itself, which it seems has developed a short circuit. The picture attached is the offending unit sitting in the lab after testing. You can see the motor, encoder and gearbox (brass/yellow coloured bits), the "worm" gear (rod covered in black grease) which drives the main telescope declination gear, and the Aluminium support structure.

This whole unit mounts on the side of the telescope, and is what drives the telescope up and down to point at different objects. That means, that until we can fix the motor, we can't use the telescope. This motor is no longer made, so we're currently hunting around for spares and/or a suitable replacement part. Until then, we won't be able to take any more images of Comet ISON :(

However, you can do a bit of solar system tracking yourself tonight (15th Feb 2013), as the small asteroid 2012-DA14 flies past the Earth at only 35,000km (to put that in context, geostationary satellites orbit at 36,000km!). Although only 50m across, 2012DA14 will be bright enough to see with binoculars because it is so close. From Oxford, it should be visible as it crosses the sky during the evening. The easiest place to catch it is probably as it crosses the handle of the Plough at about 9:30pm. The BBC has a nice graphic showing where to look;

The asteroid will appear like a faint star through binoculars, but it will appear to move relative to the background stars. At its fastest point, it will be moving at ~0.8 degrees/minute -- to give you can idea of size, the full moon is 0.5 degrees across...

Good luck looking for the asteroid, and let us know if you see it! (or if you have any spare telescope parts...)

Categories: Comet ISON | PWT | 2012DA14