From my observing run at JCMT, (James Clerk Maxwell Telescope)...
4 Apr 2012, 23:30 UTC
From my observing run at JCMT, (James Clerk Maxwell Telescope) on top of Mauna Kea, Hawai’i, a month or so ago.
The telescope operator was fantastic and took us on a tour of the telescope building one morning (which isn’t accessible to the public so that was really kind of him). This is the mirror (parked, with the roof shut), 15m/49ft in diameter, so each tile is about a metre/three feet in length. I can’t get across how big this telescope is, the building is like a round cathedral!
The mirror is not that reflective to our eyes because JCMT looks in sub-millimetre wavelengths; the light waves are far longer than optical light so the mirror only has to be shiny in the sub-mm, not the optical. They have tried cleaning the primary mirror before but it made no difference. Optical astronomers are probably weeping right now, though.
The light is gathered by the dish, focussed onto the secondary mirror you can see supported by the struts, then bounced through the hole in the middle of the dish to another mirror that directs the light to the instrument you’re using. We were using SCUBA-2. :)
