30 Meter Optical Telescopes

[antoniseb]

There is an interesting article in arXiv about the upcoming generation of ground-based insturments in the 30 meter class.

Thirty Meter Telescopes and Gravitational Lensing (http://www.arxiv.org/PS_cache/astro-ph/pdf/0409/0409236.pdf)

The article discusses the specific use for these tools in the exploration of dark matter halos around galaxies and clusters through the detailed observation of the lensing of background galaxies. [Figure 1 is a pretty cool simulation].

Another thing touched on tangentially in this paper is that JWST covers the deep infrared part of the spectrum, and that no new space based observatory covers the optical range [Hubble's Range], and that is in part because of the success of adaptive optics on ground based instuments. Realistically, a 30 meter telescope will cost about 800 million dollars to build, which while being very expensive, is still much less than the HST cost to build, launch, and maintain. Each 30 Meter telescope will have twelve times the resolution of Hubble, and more than 100 times the light gathering power.

Final plans and proposals for some of these instruments will probably be approved in 2006, with first light on one or more of them coming by 2015.

[GOURDHEAD]

Could these telescopes provide sufficient data with sufficient details to construct an accurate profile of cosmological expansion redshifting and the detection of variations in the cosmological rate of expansion over time?

What is PSF?

Is the shear referred to in the article some optical property of the telescope or an indication of what is happeneing to the viewed object or something in between the object and the observer?

[antoniseb]

Originally posted by GOURDHEAD@Sep 13 2004, 02:02 PM
What is PSF?

Is the shear referred to in the article some optical property of the telescope or an indication of what is happeneing to the viewed object or something in between the object and the observer?
PSF is Point-Spread Function. It has to do with image stability in an adaptive optics telescope.

Shear has to do with the amount of distortion seen in the shape of background galaxies because of weak gravitational lensing. Shear is one of the great hopes of those that would measure the density and location of dark matter in clusters. Specifically to your question, it is happening between the object and the observer.

[Wouter]

There are a lot of other ideas for ground based telescope. They will get larger and larger... I've spoken of the Large Binocular Telescope in an other topic, which will have two 8,4 meter mirrors that will be the equivalent of a 25m telescope.

The idea for the biggest telescope is OWL: OverWhelmingly Large telescope, which will be 100 meter in diameter :ph34r:

[antoniseb]

Originally posted by Wouter@Sep 14 2004, 06:04 PM
the Large Binocular Telescope in an other topic, which will have two 8,4 meter mirrors that will be the equivalent of a 25m telescope.
The large binocular telescope will have the angular resolution of a 25 meter telescope under certain circumstances, but it will have the light gathering power of an 11.8 meter telescope. A lot of the new science from the 30-meter scopes has to do with enhanced light-gathering for faster and deeper images. The extra resolution is increasingly available from interferometry, and so is less of an issue.

The idea for the biggest telescope is OWL: OverWhelmingly Large telescope, which will be 100 meter in diameter
Yes, I am looking forward to that thing getting first light. Plans on the table give it diameters ranging from 50 to 120 meters. It is still quite a few years away, so it remains to be seen what will actually get built, [and where].