Re: Adaptive optics for a small telescope

From: matt (electro_optic_at_bellsouth.net)
Date: 03/23/05 

Date: Wed, 23 Mar 2005 15:44:46 -0500

Gleb wrote in message
<4241d362$0$76741$e4fe514c@dreader19.news.xs4all.nl>...
>
>"matt" <electro_optic@bellsouth.net> wrote in message
>news:zak0e.49404$6g7.6011@bignews1.bellsouth.net...
>>
>
>> And now the impossible to solve problem. Since light gathering for each
>> subaperture is directly related to subaperture area, a subaperture that
is
>4
>> times smaller is going to collect 16 times less light . Do not forge that
>> the most sensitive and fastest CCD's that are used in professional S-H
>> sensors cost too much for amateurs, and the next best are still expensive
>> but with readout noise at least an order of magnitude worse . Now you
have
>a
>> system with 16 times less photons per subaperture, and 10 times noisier =
>> 160 times worse than professional setups. Such a system will not be able
>to
>> find suitably bright guide stars within the isoplanatic patch and
>therefore
>> will be useless on all but the very brightest objects , among which the
>> planets . No general purpose would be possible with such a system due to
>its
>> 160 times less sensitive wavefront sensor .
>>
>> best regards,
>> matt tudor
>>
>
>Dear Matt,
>
>please note that AO for large scopes routinely works on natural stars with
>10 to 14 magnitude. I talk about magnitude of lower than 4 which is 250 to
>1000 times brighter. It offsets the coefficient of 160 of yours.
>
>Agreed on limited scientific value, but please note that amateur astronomy
>is frequently a hobby, not a science, so the values need to be masured in
a
>different dimension.
>
>Gleb
>
>

sure, magnitude 4 for the amateur system vs. magnitude 14 for the
profesisonal offsets the performance ratio , but there's a statistical
problem . The number of available guide stars brighter than magnitude 4 is
under 1000 , and the number of brighter than magnitude 14 stars is around 50
million. Basically, there's not a chance of finding magnitude 4 stars near
objects of interest. In plain terms, the amateur AO system would not be able
to guide near any object of interest .

best regards,
matt tudor

Relevant Pages

  • Re: Adaptive optics for a small telescope
    ... >> subaperture is directly related to subaperture area, ... >> but with readout noise at least an order of magnitude worse. ... but please note that amateur astronomy ... The number of available guide stars brighter than magnitude 4 is ...
    (sci.optics)
  • Re: Adaptive optics for a small telescope
    ... >> subaperture is directly related to subaperture area, ... >> but with readout noise at least an order of magnitude worse. ... but please note that amateur astronomy ... The number of available guide stars brighter than magnitude 4 is ...
    (sci.astro.amateur)
  • Re: replicating "old" science
    ... >in many ways match or surpass the images taken in the 60s and possibly 70s ... But can today's amateur ... resolving stars; on the other hand, ... magnitude 19 as at the edge of amateur ccessibility. ...
    (sci.astro.amateur)
Quantcast