On 09/01/2019 12:28, JBI wrote:
On 1/9/19 6:50 AM, Martin Brown wrote:
On 09/01/2019 01:19, JBI wrote:
On 1/8/19 6:09 PM, Thomas 'PointedEars' Lahn wrote: JBI wrote:
* ^^^

* there doesn't give me much hope unless a super telescope is
constructed
* in space.
*
* You do not need large telescopes for good resolution if you have
several
* small ones and can do interferometry:
*
* https://en.wikipedia.org/wiki/Astronomical_interferometer

I realize both Hubble and interferometers have done a lot for
astronomy, but I wonder when the next giant step in resolution will
be.* As far as I know, there are no interferometer set ups in space.
Even doing what they do on Earth, without the atmosphere, I would
think they would do much better.

The optical interferometer setups on Earth use closure phases and
closure amplitudes to get good observables despite the atmosphere
(using the same methods as radio astronomers do - indeed mostly led by
them).

Obviously it would be better not to have corrupted raw data.

COAST was one of the very early ones and did some imaging of Betelgeuse

https://www.mrao.cam.ac.uk/outreach/...pergiants02-04


General introduction and links to other optical interferometers he
https://www.mrao.cam.ac.uk/outreach/...escopes/coast/


Interesting.* I guess this is how they're going to do it then, with
larger and larger interferometers in the future.* Did they ever try
imaging something much closer, like say Pluto, just to confirm the
resolution increase?* Maybe deemed irrelevant and a waste of time.* It
does seem to clearly show increased detail on the supergiant surfaces.

They tend to go after fairly bright near equal tight double stars and
supergiants since you need a lot of signal to noise for beam splitting.

Pluto is way too dim for interferometry at present.

Amazingly the very first optical interferometry over a 10m baseline was
done using a steel framed periscope mounted on the Mount Wilson scope in
1920 by the brilliant experimentalist Michelson & Pease.

https://www.atticusrarebooks.com/pag...al-journal-vol

It wasn't surpassed until the 1960's when Hanbury-Brown and Twiss at
Jodrell Bank built the intensity interferometer using two old WWII
searchlight parabolic mirrors and photomultipliers. His book "The
Intensity Interferometer" is an interesting if mathematical read. It is
a fairly rare book but some observatory technical libraries have a copy.

https://www.amazon.co.uk/Intensity-I...Interferometer

A much improved version was built are Narrabi (sp?) in Australia.

--
Regards,
Martin Brown