Comments on: How big is your ’scope?

By: Ross Collins

Ross Collins — Thu, 28 Dec 2006 13:13:21 +0000

“The biggest optical telescope in the world is the Keck 10 meter”

I was under the impression that SALT (Southern African Large Telescope) is currently the biggest optical telescope in the world, at least it has the largest single primary mirror:

http://en.wikipedia.org/wiki/List_of_largest_optical_reflecting_telescopes

By: Alex

Alex — Fri, 15 Dec 2006 00:39:34 +0000

Dear All,

An amateur astronomer myself, I have the privilege of working at the VLT (you can guees by my website). There seems to be some confusion regarding the ELT and the OWL. The thing is that ESO dropped the idea of the OWL, and replaced it by the ELT. Preliminary studies resulted in: The OWL is sooooo expensive, that it may never be built before 2070, so we will concentrate on building something that we will see on our lifespan, so we make it smaller, and we rename it as the ELT, saving the OWL name for some telescope in the future. This does not come free anyway. They (ESO) are talking about shutting down the operations on La Silla, an ESO owned observatorie, one of the biggest in Chile in domes count:

http://www.ls.eso.org

Hope this helps. Cheers from Paranal (Home to the VLT)

Alex.

By: Eric Anderson

Eric Anderson — Wed, 13 Dec 2006 22:43:36 +0000

DOH!! You got me there. However, that answer would suggest that telescope arrays, such as the VLA, do not count as one telescope. (Though I’m not sure if all the VLA dishes add up to more surface area than Arecibo.)

Now, for the electromagnetic spectrum-impaired (that would be me), what do you consider as the largest optical telescope in the world?

By: The Bad Astronomer

The Bad Astronomer — Wed, 13 Dec 2006 20:05:28 +0000

Eric, that’s easy: Arecibo.

By: Eric Anderson

Eric Anderson — Wed, 13 Dec 2006 19:51:43 +0000

How does one define how large a telescope is these days? Do the two Kecks, or the four VLTs count as one, since they can work together despite being housed in separate observatory domes? Is it the size of any single mirror (or parabolic surface)?

I hear Keck and VLT routinely cited as the world’s largest telescopes. But are they? The Large Binocular Telescope in Arizona has two 8.4 meter mirrors on a single alt-azimuth mount. (That counts as one telescope in my book.) The mirrors themselves are the largest-diameter monolithic telescope mirrors ever made…and given the direction technology is going (Keck-style with multiple segments), they are likely to hold that record for a long time.

Phil, can you help…what is currently the definitive largest telescope in the world? (Yeah, I work for Steward Observatory/U of A…just a little bit of pride on the line here.) Whenever people ask me the question I always have to quantify it as I’ve done above. Is it not just a simple answer anymore?

By: Astrogirl

Astrogirl — Wed, 13 Dec 2006 19:19:38 +0000

Yes KStebleton, “The Perfect Machine” is a fine book. It has a whole lot about how the 200″ mirror of the Mt. Palomar mirror was made. That telescope was the biggest that had ever been built at the time. To test the new designs that accomidated the enormous weight of the biggest telescope mirror ever created up to that point, a prototype was made. It was 1/10th the scale model of the size that Palomar was to be made. They had to test all the new engineering before the full-scale one was made.

Wonder how they’ll test the design of the 42 meter telescope? That will be interesting to see!

By: KStebleton

KStebleton — Wed, 13 Dec 2006 14:06:20 +0000

There’s an terrific book on the 200″ mirror at the Hale observatory, and the planning / politics / mechanics that went into it. Obviously, this project would dwarf the Hale mirror, but the book is WONDERFUL!

“The Perfect Machine” by Ronald Florence, at some public libraries and, of course, available online.

Kevin