Fitting another mirror segment to MAGIC II
The MAGIC gamma ray telescope is getting a twin. MAGIC II will work together with MAGIC 1 as a two-telescope array.
The first thing you notice about MAGIC is that it’s huge. The mirror is 17 m (55ft) across. This is because Gamma rays never reach the earth (unless they come from an atomic bomb). What the telescope is looking for is something called Cherenkov radiation, created by Gamma rays hitting the earth’s atmosphere 20 km up. This is very faint and very, very brief, so you need a big mirror to catch as much of it as possible.
The second thing you notice is that there’s no dome. For one thing, a dome that size would cost a fortune. For another, it would move too slowly. The telescope has to react to brief bursts of Gamma rays which may last from twenty seconds to three minutes. A dome that took three minutes to rotate would be about as much use as a chocolate poker. Thirdly, the telescope isn’t taking pictures in the usual way, so the mirror doesn’t need to be kept to optical quality.
The telescope base for MAGIC II has been on the mountain for some months. But now they’re fitting the mirror segments. Once the work is finished, they hope the instrument will be three times as sensitive. This is partly the extra mirror area, and partly newer, better instrumentation.
At present, most of the new mirror segments have been fitted, but they’re still covered with a white, protective coating. Next week they hope to finish fitting mirror segments and start aligning the lasers.
The webcam for MAGIC II is at http://www.magic.iac.es/webcams/webcam2/
