Hubble beaten by ground based adaptive optics

The debate on saving Hubble may take a new turn -- Ground based
telescopes with adaptive optics are out-doing the aging Hubble. For
example, Hubble tried and failed to find the elusive object AB Dor C in
the southern constellation of the Swordfish. The 8.2 meter telescope in
Chile found, photographed and computed the orbit leading to an
important finding, the object is twice the predicted mass and is
actually a star. This could recalibrate the mass-luminosity theory used
for this class of objects. Summary and link to photos:
http://glikglik.blogspot.com/2005/01/fat-star.html

wrote:
The debate on saving Hubble may take a new turn -- Ground based
telescopes with adaptive optics are out-doing the aging Hubble.

In some things, yes. In other things, no.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

In article . com,
wrote:
The debate on saving Hubble may take a new turn -- Ground based
telescopes with adaptive optics are out-doing the aging Hubble...

It's not news that they can outdo Hubble in some respects, especially when
raw light-gathering power is important (since some of those scopes have an
order of magnitude more mirror area).

Hubble continues to be superior -- and likely to stay that way -- in other
respects, such as ultraviolet performance and dark sky background.
--
"Think outside the box -- the box isn't our friend." | Henry Spencer
-- George Herbert |

"Henry Spencer" wrote in message
...

It's not news that they can outdo Hubble in some respects, especially when
raw light-gathering power is important (since some of those scopes have an
order of magnitude more mirror area).

Hubble continues to be superior -- and likely to stay that way -- in other
respects, such as ultraviolet performance and dark sky background.

There are two areas where space-based telescopes are destined to stay
superior (1) IR/UV, and (2) sky glow as limiting magnitude. There's no way
around those limits.

Despite great progress in adaptive optics (AO), it is immensely challenging
to
compensate for atmospheric distortion for:

(1) complex objects (not point sources like stars)
(2) objects far removed from a natural guide star (requires artificial laser
guide star)
(3) visible wavelengths -- almost all AO systems to date are near IR
(4) wide field of view -- virtually all AO systems to date are very narrow
FOV.

Nonetheless it is generally assumed that AO sophistication will grow until
all these
problems are resolved. The first "multiconjugate" AO prototype was recently
installed
at Keck, capable of handling complex objects and using a laser guide star.

Info on new Keck AO system, inc'l side-by-side shots of Hubble images:

http://www2.keck.hawaii.edu/news/lgsao/lgs_ao.html
http://cfao.ucolick.org/EO/internshipsnew/faber.pdf

The proposed 100 meter OWL (Overwhelmingly Large) telescope if built could
gather as much light in 211 seconds as the Hubble did in 100 hours for the
Hubble
Deep Field North image. It would gather about 1700 times the light of
Hubble.

Using advanced multiconjugate AO, the OWL telescope in theory could resolve
residual Apollo lunar hardware. It could resolve Jupiter/Saturn about equal
to
Voyager.

I'm not sure what the sky glow limiting magnitude is at the best terrestrial
sites, but
large terrestrial telescopes have already imaged to about 28 magnitude,
roughly
equal Hubble's limiting magnitude.

No terrestrial telescope today could equal the Hubble Deep Field or UDF. AO
doesn't
currently work over that wide a field, nor in the visual spectrum. However
it's very likely within the near future as AO sophistication improves it
will be possible.

The Giant Magellan Telescope will be 25 meters: http://www.gmto.org/

OWL: http://www.eso.org/projects/owl/

Potential of Ground Based Telescopes:
http://www.stsci.edu/stsci/meetings/...ons/Nelson.PDF