best of Hubble images

On Wed, 27 Feb 2008 19:19:39 -0500, Pudentame wrote:

> Craig wrote:
>> On Tue, 26 Feb 2008 20:47:52 -0500, Pudentame wrote:
>>
>>> Nicholas O. Lindan wrote:
>>>> "Troy Piggins" <usenet-0802.TakeThisOut@piggo.com> wrote
>>>>> http://photography-on-the.net/forum/showthread.php?t=450144
>>>>> http://photography-on-the.net/forum/showthread.php?t=450156
>>>>> http://photography-on-the.net/forum/showthread.php?t=419180
>>>>> http://photography-on-the.net/forum/showthread.php?t=451640
>>>> Not bad. All taken with a 500mm f8 Apo-doublet:
>>>> http://www.adorama.com/TKTSK9001.html?sid=12039901721249430
>>>>
>>> Why would it be f/8 instead of f/5.6?
>>
>> It looks like Tak sells an F/8 and F/5.6. Based on other images he posted
>> It looks like he as the F/8 and a 1.6 focal reducer-corrector bringing the
>> effective F/ratio to 4.5.
>
> Ok, I was wondering.
>
> If I understand, the link is for an f/5.6 scope, but he's shooting with
> an f/8 scope from the same manufacturer (same design, but smaller
> aperature??).

You do understand. There are two versions of the sky 90II. One one is F/8
and the other F/5.6.

Apature has nothing to do with it. In telescopes the focal ratio is
determined by taking the focal length (720mm) divided by Aperture (90mm in
this case) yielding F/8 focal ratio. then you use a reducer/corrector to
get the focal ratio to 4.5.

From What I'm able to find it appears that Tak is selling the 5.6 version
in which case he probably used an extension tube or barlow to get to F/8.

Unfortunately I am not as familar with Takahashi scopes as I would like to
be. Not enough $$$ in the bank for that.
 >> Stay informed about: best of Hubble images 

Craig wrote:
> Also the 60yr old Hale telescope
> recently (last year) produced the sharpest astro photo ever (besting Hubble
> and Keck etc...) through the use of Adaptive optics.

Couldn't they use the same technology on hubble & do even better?

> http://www.digitalsky.org.uk/mars/2007-12-Mars_Hubble-pbl.jpg
>
> http://www.news.com/Lucky-camera-boosts-telescope/2100-11397_3-6205940.html
>
> http://www.accessmylibrary.com/coms2/summary_0286-33247391_ITM
 >> Stay informed about: best of Hubble images 

Paul Furman wrote:
> Craig wrote:
>> Also the 60yr old Hale telescope
>> recently (last year) produced the sharpest astro photo ever (besting
>> Hubble
>> and Keck etc...) through the use of Adaptive optics.
>
> Couldn't they use the same technology on hubble & do even better?
>

They should be able to. They've updated Hubble's instruments several
times before, but I think NASA is planning to abandon Hubble.

Supposedly, there's a more advanced telescope in development, but
there's going to be a long gap between the time Hubble dies & the newer
scope flies.

I think the problems with the shuttle program have affected the
decision. With the demands of the international space station, they
don't have enough flight capability to run a mission out to Hubble.

The shuttle itself is being abandoned, due to it's safety issues,
although I don't think they've decided on a follow-on vehicle yet.

I don't know why they can't just grab Hubble on one of their missions
and move it over near the space station where the station crew could do
EVAs over to Hubble. Any required repair parts could be sent up in the
Russian Soyuz supply capsules.
 >> Stay informed about: best of Hubble images 

On Wed, 27 Feb 2008 19:47:45 -0500, Pudentame wrote:

> Paul Furman wrote:
>> Craig wrote:
>>> Also the 60yr old Hale telescope
>>> recently (last year) produced the sharpest astro photo ever (besting
>>> Hubble
>>> and Keck etc...) through the use of Adaptive optics.
>>
>> Couldn't they use the same technology on hubble & do even better?
>>
>
> They should be able to. They've updated Hubble's instruments several
> times before, but I think NASA is planning to abandon Hubble.

Uhh no. Read teh earlier posts. Adaptive Optics (AO) are for canceling out
atmospheric turbulence. Since HST is above the atmosphere AO has no effect
on it.
>
> Supposedly, there's a more advanced telescope in development, but
> there's going to be a long gap between the time Hubble dies & the newer
> scope flies.
>
> I think the problems with the shuttle program have affected the
> decision. With the demands of the international space station, they
> don't have enough flight capability to run a mission out to Hubble.
>
> The shuttle itself is being abandoned, due to it's safety issues,
> although I don't think they've decided on a follow-on vehicle yet.
>
> I don't know why they can't just grab Hubble on one of their missions
> and move it over near the space station where the station crew could do
> EVAs over to Hubble. Any required repair parts could be sent up in the
> Russian Soyuz supply capsules.

Not possible for a whole lot of reasons too complex to get into in this
thread.

Craig
 >> Stay informed about: best of Hubble images 

In message <xfjxj.14063$Ej5.12244@newssvr29.news.prodigy.net>, Paul
Furman <paul- RemoveThis @-edgehill.net> writes
>Craig wrote:
>> Also the 60yr old Hale telescope
>> recently (last year) produced the sharpest astro photo ever (besting Hubble
>> and Keck etc...) through the use of Adaptive optics.
>
>Couldn't they use the same technology on hubble & do even better?

No. The Hubble is truly diffraction limited but of very modest finite
aperture (small by comparison to many ground based scopes). But it is in
orbit so isn't affected at all by atmospheric seeing. You are lucky to
get below 1" arc resolution in a time exposure from a ground based
scope.

All ground based scopes suffer this affliction of seeing through
turbulent air thermals. Adaptive optics correction is only really useful
for larger ground based scopes (roughly 1m class and above). Although
tip-tilt correctors are now available to amateurs on more modest
apertures.
>
>> http://www.digitalsky.org.uk/mars/2007-12-Mars_Hubble-pbl.jpg
>>
>>http://www.news.com/Lucky-camera-boosts-telescope/2100-11397_3-6205940.
>>html
>> http://www.accessmylibrary.com/coms2/summary_0286-33247391_ITM

Some amateur folk with webcams, larger scopes and stacking software are
getting pretty close to Hubble quality images of the brighter planets
these days by sifting through thousands of short exposures for the
handful of lucky ones.

Regards,
--
Martin Brown

--
Posted via a free Usenet account from http://www.teranews.com
 >> Stay informed about: best of Hubble images 

Martin Brown wrote:
> Paul Furman writes
>> Craig wrote:
>>> Also the 60yr old Hale telescope
>>> recently (last year) produced the sharpest astro photo ever (besting
>>> Hubble
>>> and Keck etc...) through the use of Adaptive optics.
>>
>> Couldn't they use the same technology on hubble & do even better?
>
> No. The Hubble is truly diffraction limited but of very modest finite
> aperture (small by comparison to many ground based scopes).

The amateur examples surely weren't working with larger ground
telescopes though?

> But it is in
> orbit so isn't affected at all by atmospheric seeing. You are lucky to
> get below 1" arc resolution in a time exposure from a ground based scope.
>
> All ground based scopes suffer this affliction of seeing through
> turbulent air thermals. Adaptive optics correction is only really useful
> for larger ground based scopes (roughly 1m class and above). Although
> tip-tilt correctors are now available to amateurs on more modest apertures.
>>
>>> http://www.digitalsky.org.uk/mars/2007-12-Mars_Hubble-pbl.jpg
>>>
>>> http://www.news.com/Lucky-camera-boosts-telescope/2100-11397_3-6205940.
>>> html
>>> http://www.accessmylibrary.com/coms2/summary_0286-33247391_ITM
>
> Some amateur folk with webcams, larger scopes and stacking software are
> getting pretty close to Hubble quality images of the brighter planets
> these days by sifting through thousands of short exposures for the
> handful of lucky ones.

So Hubble could stack & stitch too I would think.
 >> Stay informed about: best of Hubble images 

"Paul Furman" <paul- DeleteThis @-edgehill.net> wrote

> So Hubble could stack

All Hubble pictures are the same - each is as good as it is going
to get and each is as bad as it is going to get - averaging them
out doesn't have any benefit.

Ground based pictures suffer from atmospheric distortion,
vibration and thermal effects - all adding up, loosely,
as noise.

The effects of perfect noise can be reduced by the square
root of the number of averaged samples - stacking 4 images
would reduce the noise by a factor of 2; stacking 16 would
reduce it by a factor of 4 ...

This square root improvement is as good as it gets and in
real life the benefits are less, and a point of diminishing
returns is soon met.

I am sure NASA does averaging for any benefit they can gain.
NASA has been exploiting every trick in the book, and writing
several new books to boot, to make Hubble pictures look better.
It is the only bit of positive PR NASA has.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.darkroomautomation.com/index.htm
n o lindan at ix dot netcom dot com
 >> Stay informed about: best of Hubble images 

On Wed, 27 Feb 2008 12:08:33 -0800 (PST), Mark Sieving wrote:

> On Feb 27, 1:56 pm, Paul Furman <pa....DeleteThis@-edgehill.net> wrote:
>> Craig wrote:
>>> Also the 60yr old Hale telescope
>>> recently (last year) produced the sharpest astro photo ever (besting Hubble
>>> and Keck etc...) through the use of Adaptive optics.
>>
>> Couldn't they use the same technology on hubble & do even better?
>
> The main purpose of adaptive optics is to cancel out atmospheric
> disturbances. Since Hubble is outside the atmosphere to begin with,
> adaptive optics wouldn't help much.
>
> Hubble's primary mirror is 2.4 meters, which is fairly small by
> current land based standards. What you want to do is put a 6 to 10
> meter telescope in orbit. Then you'll get some images to write home
> about.

Hear hear!!
 >> Stay informed about: best of Hubble images 

In message <47c6052a$0$24081$4c368faf@roadrunner.com>, Pudentame
<no.one.TakeThisOut@no.were.invalid> writes
>Paul Furman wrote:
>> Craig wrote:
>>> Also the 60yr old Hale telescope
>>> recently (last year) produced the sharpest astro photo ever (besting
>>>Hubble
>>> and Keck etc...) through the use of Adaptive optics.
>> Couldn't they use the same technology on hubble & do even better?
>>
>
>They should be able to. They've updated Hubble's instruments several
>times before, but I think NASA is planning to abandon Hubble.

The only thing that they really can gain on is by putting the latest
generation of maximum quantum efficiency detectors in place of the older
ones. Space qualified CCDs always lag behind the ground based ones.

Not quite abandoned (although very nearly). It was saved by the public
outcry and intense lobbying by the scientific community.

There is one more servicing mission scheduled for the Shuttle (which
makes a nice change from stuffing more humans into a useless orbital tin
can called ISS). They plan to upgrade the instruments and swap out
defective parts with the intention of extending the life by 5 more years
9 as well as giving it improved sensors for additional capabilities. eg

http://hubblesite.org/servicing_mission_4/

If we are lucky it may keep going for more than the design lifetime with
a bit of coddling. At least that is what the guy giving a presentation
on it earlier this month said.
>
>Supposedly, there's a more advanced telescope in development, but
>there's going to be a long gap between the time Hubble dies & the newer
>scope flies.

The James Webb scope will be bigger and optimised for IR observations so
it will not be quite the same thing.
>
>I think the problems with the shuttle program have affected the
>decision. With the demands of the international space station, they
>don't have enough flight capability to run a mission out to Hubble.

The ISS is a perfect boondoggle. It has produced zero useful science so
far and serves only to provide a safe destination to fly the Shuttle to.
>
>The shuttle itself is being abandoned, due to it's safety issues,
>although I don't think they've decided on a follow-on vehicle yet.
>
>I don't know why they can't just grab Hubble on one of their missions
>and move it over near the space station where the station crew could do
>EVAs over to Hubble. Any required repair parts could be sent up in the
>Russian Soyuz supply capsules.

It is a heck of a long way away from the ISS.

The main reason they almost decided not to do the servicing mission at
all was that from the Hubbles orbit the Shuttle cannot make an orbital
transfer to the ISS from there to give the astronauts some place of
refuge.

Also you need an immense amount of training and practice to get bulky
parts in and out of a confined space without damaging the instruments
whilst wearing a pressure suit and heavy gloves.

Regards,
--
Martin Brown

--
Posted via a free Usenet account from http://www.teranews.com
 >> Stay informed about: best of Hubble images 

"Nicholas O. Lindan" <see.TakeThisOut@sig.com> wrote in message
news:13sc1deb76jsn0a@corp.supernews.com...
> "Paul Furman" <paul-.TakeThisOut@-edgehill.net> wrote
>
>> So Hubble could stack
>
> All Hubble pictures are the same - each is as good as it is going
> to get and each is as bad as it is going to get - averaging them
> out doesn't have any benefit.
>
> Ground based pictures suffer from atmospheric distortion,
> vibration and thermal effects - all adding up, loosely,
> as noise.
>
> The effects of perfect noise can be reduced by the square
> root of the number of averaged samples - stacking 4 images
> would reduce the noise by a factor of 2; stacking 16 would
> reduce it by a factor of 4 ...
>
> This square root improvement is as good as it gets and in
> real life the benefits are less, and a point of diminishing
> returns is soon met.
>
> I am sure NASA does averaging for any benefit they can gain.
> NASA has been exploiting every trick in the book, and writing
> several new books to boot, to make Hubble pictures look better.
> It is the only bit of positive PR NASA has.
>
I have heard of software that removes anything that changes from shot to
shot, but keeps whatever remains in each shot.....Under the theory that the
noise will move from place to place, but the real data doesn't change in
position. Is this what they do?
 >> Stay informed about: best of Hubble images 

"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message
news:RcPK1>
>

Also you need an immense amount of training and practice to get bulky
> parts in and out of a confined space without damaging the instruments
> whilst wearing a pressure suit and heavy gloves.
>
I should think that they would design an instrument that was modular, so
they could just swap modules in their space suits, and then do the repairs
without a vacuum, back inside a normal atmosphere. We did that without being
in space, when tunnel time was expensive inside a high energy physics
collider....We would just go in and swap out a defective part, and then do
the actual repairs somewhere else while the machine continued to operate.
 >> Stay informed about: best of Hubble images 

On Thu, 28 Feb 2008 15:14:02 -0800, William Graham wrote:

> "Nicholas O. Lindan" <see.DeleteThis@sig.com> wrote in message
> news:13sc1deb76jsn0a@corp.supernews.com...
>> "Paul Furman" <paul-.DeleteThis@-edgehill.net> wrote
>>
>>> So Hubble could stack
>>
>> All Hubble pictures are the same - each is as good as it is going
>> to get and each is as bad as it is going to get - averaging them
>> out doesn't have any benefit.
>>
>> Ground based pictures suffer from atmospheric distortion,
>> vibration and thermal effects - all adding up, loosely,
>> as noise.
>>
>> The effects of perfect noise can be reduced by the square
>> root of the number of averaged samples - stacking 4 images
>> would reduce the noise by a factor of 2; stacking 16 would
>> reduce it by a factor of 4 ...
>>
>> This square root improvement is as good as it gets and in
>> real life the benefits are less, and a point of diminishing
>> returns is soon met.
>>
>> I am sure NASA does averaging for any benefit they can gain.
>> NASA has been exploiting every trick in the book, and writing
>> several new books to boot, to make Hubble pictures look better.
>> It is the only bit of positive PR NASA has.
>>
> I have heard of software that removes anything that changes from shot to
> shot, but keeps whatever remains in each shot.....Under the theory that the
> noise will move from place to place, but the real data doesn't change in
> position. Is this what they do?

Not really. Since CCD noise is random in nature, stacking multiple images
averages out the noise. Using (subtracting)dark frames from the light subs
also helps clean up the images.
 >> Stay informed about: best of Hubble images 

Craig wrote:
> On Wed, 27 Feb 2008 19:47:45 -0500, Pudentame wrote:
>
>> Paul Furman wrote:
>>> Craig wrote:
>>>> Also the 60yr old Hale telescope
>>>> recently (last year) produced the sharpest astro photo ever (besting
>>>> Hubble
>>>> and Keck etc...) through the use of Adaptive optics.
>>> Couldn't they use the same technology on hubble & do even better?
>>>
>> They should be able to. They've updated Hubble's instruments several
>> times before, but I think NASA is planning to abandon Hubble.
>
> Uhh no. Read teh earlier posts. Adaptive Optics (AO) are for canceling out
> atmospheric turbulence. Since HST is above the atmosphere AO has no effect
> on it.

OK


>> I don't know why they can't just grab Hubble on one of their missions
>> and move it over near the space station where the station crew could do
>> EVAs over to Hubble. Any required repair parts could be sent up in the
>> Russian Soyuz supply capsules.
>
> Not possible for a whole lot of reasons too complex to get into in this
> thread.

As if that's ever stopped anyone before. ;-D
 >> Stay informed about: best of Hubble images