Friday, 3 April 2009

Working in unison

Last night, to calm the nerves a little before we went live on air, I went out and took a few pictures of some Mauna Kea observatories in the middle of the night. That was a bit silly really, because 1) my intention was always to stay well out of view of the polycom's camera, which I did, and 2) while in the wings during the live webcast pull faces and do whatever I could to put everyone off (which I didn't do, of course!).

That first picture of the submillimeter telescopes turned out so well I took another zoomed in shot of the CSO and JCMT. The picture is a little noisier and not so dramatic, I'll live with that, but it shows both telescopes pointing in the same place. Was that simply coincidence? No, it wasn't.

Unfortunately, at least for us, the live webcast died just as the JCMT went on air which was a shame because it was an important night. The JCMT was hooking up with the CSO and the SMA on Mauna Kea as well as telescopes thousands of miles away in California and Arizona. They were all looking at the same thing at the same time using something called Very Long Baseline Interferometry, or VLBI. It's an incredibly complicated technique of observing, but if you get it right, hugely rewarding. It's something that radio telescopes have been doing for some years now, but the method gets harder as you shorten the wavelength (e.g., towards optical wavelengths, light our eyes can see). The Keck telescopes have been doing interferometry at optical wavelengths for some time now, but over a distance of a hundred yards or so, not thousands of miles! Optical interferometry at those sorts of distances is still quite a way in the future, but one day I'm sure will happen. Submillimeter wavelengths are shorter than radio waves, so at least we're now on the way to non-radio-wavelength VLBI.

Anyway, I'm digressing. The whole idea of VLBI is to create a telescope with a dish (in optical astronomy, a mirror or lense) with an effective diameter of thousands of miles. In simple terms, the larger a dish, the higher resolution it can achieve, that is, the more detail it can see. So the idea is to artificially create a telescope that's a significant size of the planet. The sensitivity won't be the same as a dish that large, but the resolution will be.

Getting all this to work is a massive task both technically and logistically. From what I've heard, those two hurdles have been overcome for the Mauna Kea observatories, but the data still have to come in from the observatories on the mainland and only then will we know if it's worked. I'll let you know when I find out!

On the other hand, UKIRT (foreground) and Gemini (background) were certainly not looking at the same thing!

Note that both observatories have windows or gaps in the side of their domes. Those are used to allow air into the domes to help equalize the temperature between the inside of the domes and the air outside, just like you might do at home on a hot summer's day. This helps to reduce local turbulence caused by rising warm air and therefore dramatically improve the image quality both telescopes deliver. Although VLBI might be quite some way in the future for telescopes such as these, they do what they can to get the best images possible!

And that's the end of the lecture. It'll be cat pictures tomorrow I think...

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