inside the jcmt


I was up at the JCMT last week helping out with ‘Imiloa and SkySkan film crew as they collected footage of the telescope for their 3D productions which they show at the ‘Imiloa planetarium. They are doing all the telescopes on Mauna Kea and this past week was our turn. They have a nice set up. Two Nikon D700 cameras with mounted next to each other at the inter-ocular distance, so that when the images are projected onto the dome with the 3D glasses on, the 3d you get is actually very realistic. They had two of these set ups (i.e. 4 cameras) which they rigged up at various positions around the dome. The cameras would then be set to take up to 7 frames per second for about half an hour or so (you do the math as to how many images that is!). Ben, one of our Telescope Systems Specialists, would set the telescope in motion as the cameras fired away. I can’t wait to see what the final results will be like. Especially in the big dome at the ‘Imiloa Astronomy Center.

While I was there, mostly shepharding and not always successfully trying to stay out of the way, I tried to take a few shots of my own. The image above shows a detail of the support structure on the back of the 15-m JCMT dish.

Continue reading “inside the jcmt”

“it’s a bit breezy”

This was a quote from our observer of the past few nights as I talked to him last night. They had just abandoned the summit because of the high winds. It is now Saturday morning and, as is customary for most Mauna Kea astronomers, I checked the weather page.

This is what I found in the UH88 panel.

uh88windspeedI don’t know if the UH88-inch telescope’s anemometer has got stuck or is broken, but I suspect that it has as 125 mph seems really high to me, especially as you compare to what is currently being measured at the other telescopes. I’ve just tried a couple of reloads over the past 10 minutes and all of the other numbers have updated slightly, except for the wind speed. Comparing to UKIRT (which is next door to UH88-inch) the wind is ONLY at 50 mph.

Looking at the JAC’s meteogram we can see the wind speeds measured at UKIRT and JCMT over the course of the night.

ukirtwindspeedThe line at the top is UKIRT and that below is JCMT (which lies in the valley below and west of the summit and so usually registers lower wind speeds). It seems like we hit a peak of 90 mph last night and its about 60 mph as I write this.

I guess it’s fair to say that there is still a stiff breeze blowing.

summit sunrise #4

summitsunrise4I haven’t done one of these for a while now as I haven’t been up to the summit since before Christmas. So here’s an image I took on my previous visit, from the gantry of the JCMT, of a snow covered Pu’u. The Sun was rising to the east and I used the light it cast onto the side of the Pu’u to split the composition between light and dark and into something that I thought would look interesting.

Astronomy with lasers

As I said in the last post, I’m on the mountain for the next week or so. I’m just working the last quarter of the night for the next few nights, commissioning a new instrument at the JCMT. So I made my way up to the summit leaving the Hale Pohaku Hotel & Resort for Stray Astronomers at about 1:30am. The sky was beautiful and clear – it is one of the natural wonders of the world, truly amazing and I never, ever get used to seeing the night sky from the summit. However, when I looked over at the ridge above us where the biggies are (Subaru and the two Kecks) I noticed this bright orange line shooting out of the Keck I dome into the sky. No, not James Bond, but adaptive optics with lasers.

The technology is actually quite cool. At Keck they call it LGS – laser guide stars. Of course adaptive optics with natural guide stars (NGS) has been around for a while, but it depends on the presence of stars near where you want to observe (within about 30 arcsecs or so). Despite there being “billions and billions” of stars in our Galaxy, apparently this leaves something like 99% of the sky unviewable with adaptive optics. Hence the genesis of this new technology. The laser is shot up in the direction of the astronomical object of interest where it interacts with the sodium layer high up (about 90km) in our atmosphere. The sodium atoms (which got to be there by virtue of meteor strikes, etc, by the way) are excited into emission by the laser and the telescope uses it as an artificial source to correct the aberrations that are introduced by the atmosphere.

All pretty cool and it looks cool as well. I happened to have my camera with me (!) and so went to the back of the JCMT, onto the gantry and set up a long exposure on a tripod. This is what I got:

_mg_5453_ijfr1 _mg_5454_ijfr Not that great, but cool nonetheless. If you look closely (click on the images) you’ll see double stars and two lines for the laser. That’s because the way that the JCMT telescope is built, the whole building rotates when we follow sources around the sky. So the double stars and laser tracks are because the telescope moved in the middle of my exposures. (We’re not going to stop working just because I want to take a photograph!). These were a 1.5 and 3 minute exposures, respectively.

If the lasers are out again in the next couple of nights I’ll set up the tripod outside and see if I can capture a better shot. In the meantime, here’s a really nice image from the Keck website.