Time Lapse Video of the VLT In Chile 105
schwit1 writes with a video "captured by Stephane Guisard and Jose Francisco Salgado at the European Southern Observatory's Very Large Telescope (VLT) in Chile's Atacama Desert. And it might make you cry. What makes this time lapse particularly amazing — because we've all seen plenty of time lapse videos of the night sky — is the four telescopes in the foreground. Watching these instruments work against a black background would be endlessly fascinating on its own. Unfortunately you won't be able to pay them too much attention. Because damn, what a sky."
Why not link to the original video? (Score:5, Informative)
Instead of sending everyone to another blog to view the postage stamp sized video in an embedded player, here's the link to the original video at YouTube:
http://www.youtube.com/watch?v=wFpeM3fxJoQ [youtube.com]
Nice use of HDR in the video. How did they do that?
Re:Why not link to the original video? (Score:5, Informative)
You can read about these techniques in more detail at the very bottom of this tutorial [timescapes.org] under the header labeled Timelapse "Holy Grail"? Sunset, Sunrise, Day to Night Transitions.
Re:Orange Laser?? (Score:5, Informative)
Yup. As others have pointed out, it's a laser guide star. In a nutshell, the basic idea is that the thing (e.g. a star) that the telescope's looking at gets all smeared out & wibbly wobbly by foreground atmospheric variations (twinkling). The idea here is that if you generate a bright spot in the sky with known properties close to the thing you want to observe, then by comparing what your spot looks like with what you know it should look like, you can calculate which tiny variable distortions you want to add in to the perfect curve of your mirrors to counteract these atmospheric wobbles. The thinking is that if you can correct the wobbles in your fake "star" & it's close to the real one on the sky, then the correction can be assumed to be about the same.
The actual corrective distortions to the mirror are handled by things that are basically very precise, very small computer-controlled pistons that can apply corrections many per second.
(For the record, IAAA - I Am An Astrophysicist ,although I've worked at other observatories - not specifically at the VLT).
Re:Orange Laser?? (Score:2, Informative)
The shutters regulate temperature; temperature changes make light passing though air "wobble".