The largest telescopes in the world

In article ,
Paul Schlyter wrote:

Restored in 1998 with a modern glass mirror

The replacement mirror is aluminium.

2003- 10.4 m CTC, Canary Islands, Spain

GTC (Gran Telescopio Canarias), and it isn't operating yet.


Patrick Wallace
__________________________________________________ _______________________

On Wed, 01 Oct 2003 19:57:48 +0200, Paul Schlyter
wrote:

And then we also have the
radio telescopes (yep, Arecibo is much larger than Keck!).

Maybe you should measure the aperture in units of the wavelength the instrument
is designed for. That kind of puts optical and radio instruments on a more equal
footing.

_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

Ante Perkovic wrote in message ...
Paul Schlyter wrote:

The world's largest telescope today is of course the twin Keck
telescopes, even taken one by one.

Wrong!

It's Arecibo!

Ante

Nope, the largest *optical* telescope is the 10 meter Keck (optical is
assumed since we are on the newsgroup for amateur astronomy). The
largest *radio* telescope is not necessarily Arecibo, but occurs when
10 radio dishes are linked to create the Very Long Baseline Array
(8,600 km wide, or about 5,344 miles).
--
David W. Knisely
Prairie Astronomy Club: http://www.prairieastronomyclub.org
Hyde Memorial Observatory: http://www.hydeobservatory.info/

Paul Schlyter wrote:

Thanks everybody for your comments! I have now updated my list, and I
believe
it's now fairly complete from 1783 and on.
1948-1974 5.0 m Hale 200-inch reflector, Palomar Mountain,
California, USA
1974-1993 6.0 m BTA-6, Mt Pashtoukov, Caucasus, Russia
1993-2003 9.8 m Keck, Mauna Kea, Hawaii, USA
2003- 10.4 m CTC, Canary Islands, Spain

Interesting links related to the history of telescopes:
-------------------------------------------------------

Paul,

Make room for the LBT. 2, 8.4 meters with adaptive optic secondary mirrors

See: http://medusa.as.arizona.edu/lbtwww/

Dan

Ante Perkovic wrote:
Wrong!

It's Arecibo!

and then was subsequently rebutted a few times.

The danger in raising the pedantry flag, I've found, is that there's
always someone willing to shoot yours down and raise theirs in its
place.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

In sci.astro David Knisely wrote:
Ante Perkovic wrote in message ...
Paul Schlyter wrote:

The world's largest telescope today is of course the twin Keck
telescopes, even taken one by one.

Wrong!

It's Arecibo!

Ante

Nope, the largest *optical* telescope is the 10 meter Keck (optical is
assumed since we are on the newsgroup for amateur astronomy). The
largest *radio* telescope is not necessarily Arecibo, but occurs when
10 radio dishes are linked to create the Very Long Baseline Array
(8,600 km wide, or about 5,344 miles).

Or (past tense) when assorted ground-based dishes were working
interferometrically with Japan's HALCA at baselines up to a biut
more than two Earth diameters. Granted, this is a very different
kind of thing than the largest single device working at whatever wavelength.

And to be more pedantic still, the effective entrance areas of some of the
Cerenkov systems detecting high-energy photons through interactions
in the upper atmosphere are now reaching many kilometers.

Bill Keel

Mike Simmons wrote:

Paul Schlyter wrote:

Mike Simmons wrote:

Paul Schlyter wrote:

I'd like to assemble a list of the world's largest telescopes, in
chronological order.

I've always been fascinated by this and hoped that someone would put
such a list together. There was a great article in Sky and Telescope a
few years ago that should help but I can't locate it. It had a list of
all of the world's largest telescopes of various designs and included
their commissioning dates. The section on refractors should prove
useful as that's where the older instruments are.

Could you try to remember, to the best of your ability, how many years
ago that article appeared? I have Sky and Telescope since about 40
years back, and can look through them, and it would be nice to have
the search narrowed down as much as possible.

I'm sure it was published no longer ago than 1996. I think it was at
least two years ago but I'm not sure of that. It was a feature article
so it shouldn't be that hard to find. Sky and Tel has an online search
of the archives in its section on buying back issues that can narrow the
candidates considerably. I tried searching it but there were a few
possibilities based on the titles so I wasn't sure which one it was.

Found it! It apperaed in the August 2000 issue of Sky and Telescope.
There were lists of the world's largest scopes, the world's largests
Schmidt telescopes (where even little Sweden's instrument in Kvistaberg,
some 30 km NW of Stockholm, made it to the list), and the world's
largest
refractors of all times.

1948-1974 5.0 m Hale 200-inch, Mt Palomar, California, USA

The correct location name is "Palomar Mountain".

OK, I've corrected that in my list. But it's "Mt Wilson" and not
"Wilson Mountain" ?

"Mount Wilson" is correct. When first named it was referred to as
"Wilson's Peak" but that name hasn't been used in 100 years. The
original name of the observatory -- at the time of first light of the
60-inch and 100-inch -- was "Mount Wilson Solar Observatory". The word
"Solar" was dropped after dedication of the 100-inch (some time in 1918,
I believe).

I guess it would be hazardous to try to observe the Sun with the Hooker
telescope... :-)

But wasn't Mt Wilson first with the "tower telescope" for solar
observations?

Mike Simmons


--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://www.stjarnhimlen.se/
http://home.tiscali.se/pausch/

Great list! I hope you will ask Joe to add it to the FAQ when the
list stabilizes.

If you create a separate list for non-monolithic mirrors, I think the
Multiple Mirror Telescope has to be included. It became operational
about 1980, but there are probably reports in the ADS that would give
a more precise date. Perhaps the LBT, VLT _interferometer_, and Keck
_pair_ belong in the same list; all are used in the combined mode for
interferometry. It's hard to know what to do about interferometers,
but I think the relevant parameter is probably collecting area, not
baseline.

In article ,
Paul Schlyter writes:
I guess it would be hazardous to try to observe the Sun with the Hooker
telescope... :-)

Oddly enough, I think the 1.5-m telescope on Mt. Wilson was used to
observe the Sun. Also the Hale 5-m and the 3-m IRTF, but I think not
the Hooker. The "trick" is that the observations were done at mm
wavelengths with black polyethelene covering the entrance aperture.
My memory is not certain, however, and no doubt an ADS search would
turn up the true facts. If anyone checks, 1970 to 1985 would
probably be about the right time range.

This operation is indeed hazardous to equipment, if not to personnel.
There was one occasion on which the 1.55-m "Two Micron Sky Survey
Telescope" (Bob Leighton's epoxy mirror) was being used in this mode,
and a small flap of the polyethelene came loose. The sunlight
hitting the focus punched a hole in the dewar entrance window,
leading to catastrophic failure of the dewar. Must have been very
exciting for the observer, who normally sat perhaps 2 m from the
telescope and dewar. (I wasn't there at the time but have used the
telescope and know where the control panel was.)

On another occasion -- not involving mm observations or polyethelene
-- while observing Venus or a comet or something else close to the
Sun, a solar image was projected on the dome wall and allegedly came
close to starting a fire. I don't remember which telescope this was.

It is possible to observe the Sun safely -- as is proved by solar
telescopes and by numerous amateurs every day -- but you really do
need to be careful.

--
Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA
(Please email your reply if you want to be sure I see it; include a
valid Reply-To address to receive an acknowledgement. Commercial
email may be sent to your ISP.)

"Steve Willner" wrote

If you create a separate list for non-monolithic mirrors, I think the
Multiple Mirror Telescope has to be included. It became operational
about 1980, but there are probably reports in the ADS that would give
a more precise date.

May 9, 1979 was the dedication date. It took a few years afterward to really
get it off the ground, so to speak.

Howard Lester
MMT Observatory

"Steve Willner" wrote in message
...

Great list! I hope you will ask Joe to add it to the FAQ when the
list stabilizes.

If you create a separate list for non-monolithic mirrors, I think the
Multiple Mirror Telescope has to be included.

The MMT no longer has multiple mirrors. They were entirely
replaced with a single spin-cast 6.5 m mirror not too long ago.