Observing, Day 2, Part 1

Sunday, September 27 9:30 PM Eastern [3:30 PM Hawaii time]

I had planned to head to bed last night after I sent my message to you around 2 AM, but as I was leaving the computer room, I ran into Amy Barger, an astronomer who I knew from my time at the University of Wisconsin. One of the nice parts about being at HP (Hale Pohaku, the astronomers' dorm) is that you often run into people you know. There are about a dozen different telescopes on the summit of Mauna Kea, and all of the astronomers using them stay at HP. Astronomy is a small enough field that many people know each other, so it's not unusual to be observing at the same time as someone you know, and it's also a good place to meet new people and to catch up on exciting new results in astronomy, sometimes things that were found only the night before!

Amy and I chatted for a few hours, and I finally turned in around 4:00 AM. I was tired, but not unhappy to have stayed up later than I planned, since I need to shift myself over to a night-time schedule since I'll be observing all night tonight and tomorrow. My plan was to sleep in as late as possible to try to make the adjustment, and I managed to sleep until about 1:30 PM. Coming down to "breakfast" around 2:00, I found (to my surprise) that Gary (my collaborator from Britain) was still awake, so we chatted a bit about how last night's observing went.

The weather had not been great (I had already learned this from Amy, who is observing the first half of the night on the same telescope). But it turned out that Gary and Bob managed to accomplish a surprising amount. This is good news - this kind of weather would have stopped us in our tracks when we first started this research project about six years ago, but the new camera is sensitive enough that we can get good data even in weather that's not so great. At the wavelengths where we're observing, the atmosphere is not very transparent, so even a little bit of water vapor in the air cuts out a lot of the incoming radiation. That's why we're here on Mauna Kea - it's one of the few places in the world where one can even make this type of observation. It has two big advantages: elevation and climate. At 14,000 feet, we're sitting above a lot of Earth's atmosphere, so it doesn't block our view. And the climate is quite good, in that it's extremely dry up here. Dry is probably not what you think of when you think of Hawaii, but on top of Mauna Kea the climate is essentially that of a desert. The moist air that comes in off the Pacific typically comes part way up the slopes of the mountain and then condenses to form clouds at an altitude of about 6000-8000 feet. And the dry climate affects the observers, too - I've had a bit of a headache most of the day, probably from dehydration. I'll try to drink more fluid tonight.

And what did we find out from our observations last night? Well, like a lot of scientific projects, the results aren't cut-and-dried. Several of the binaries showed detectable submillimeter emission, meaning that they definitely have disks. And those disks may be big enough to form planets, and least relatively small planets like the Earth. But several other binaries did not show any emission, so it seems like they don't have substantial disks. So we don't have a broad, general picture of how these systems behave yet - we need more data.

4:05 AM Eastern [10:05 PM Hawaii time]

I spent the afternoon talking with Bob about plans for tonight. We agreed on a list of binaries to observe, and then we turned to plans for the future. In particular, we're debating whether or not to put in another proposal to observe some additional stars in another part of the sky. We decided that it might be useful to do so, so after dinner I spent several hours putting together a list of possible target stars.

Our observing tonight doesn't start until 1:30 AM - unlike most telescopes where the visiting observer would have the whole night, the JCMT observing is divided into two shifts: 5:30 PM - 1:30 AM, and 1:30 AM - 9:30 AM. Part of the reason for this is that when you're observing at wavelengths that are far outside the visible spectrum, sunrise and sunset don't mean much. The sky emits relatively little submillimeter emission even in the daytime, so we can continue to observe after the Sun comes up (as long as we don't point the telescope straight at the Sun!)

The telescope operator stopped by our table at dinner and said that the weather for tonight looks somewhat better than it did last night, so I'm optimistic that we can accomplish a fair amount. But first, I'm going to try to catch a few more hours' sleep before we head up the mountain.

More later,


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Eric Jensen <ejensen1@swarthmore.edu>
Last modified: Sun Jun 8 16:15:27 2003