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aandrei

14 Feb 2014 13:16


Lucrurile cele mai interesante sunt la granita cunoasterii

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Eu sunt pre-incepator.
Indraznesc sa deschid totusi un subiect la avansati intrucat am impresia ca astazi se pot documenta si obiectiva lucruri care in trecut tineau de opinia personala (ex. suprematia aparenta a refractoarelor mici fata de telescoapele mari in astrofotografie).

Am gasit pe net informatii care arata ca telescoape terestre ating rezolutii superioare lui Hubble:

"Observing and Results
A recent observing trip (July 2007) to the Palomar 200 inch telescope has been extremely successful. The images we obtained are the highest resolution direct images, about 35 milliarcsec FWHM, ever obtained either from the ground or from space in the visible at about twice the resolution of the Hubble Space Telescope.
http://www.ast.cam.ac.uk/research/lucky/"

Am gasit explicatia pentru care refractoarele PAR a avea imagini mai bune decat reflectoarele mari:

"Actual comparison of Airy patterns from several telescopes of different apertures, all shown at the same arc-second scale. Note that the small refractor and Maksutov have well-shaped diffraction patterns that make the stars look good, but the angular size of the stars is much larger than the telescopes with greater aperture. This is a direct recording of the likely reason that refractors appear to out-peform larger aperture SCT's."

Am gasit un program care OBIECTIVEAZA manevrele de colimare, necesitand doar suprapunerea unui punct rosu peste centrul stelei, chiar in situatia unui seeing mediocru:

What does MetaGuide do?
Allows a high power view of a star and its diffraction pattern even when seeing is not ideal
Shows a "coma dot" over the live star that guides collimation so the user just centers the dot over the star. This takes the guesswork out of collimation while keeping it interactive and realtime
Compares the observed diffraction pattern with theory, including secondary obstruction effects
Provides a simple "dump" of the raw and steady images of the star, along with a plot that shows how the stellar profile compares to theory, plus numeric values for the actual and theoretical FWHM's. This provides an objective and quantitative measure of a telescopes true performance, with less dependence on good seeing
Measures flexure/mirror flop using two telescopes, two web-cams, and two instances of MetaGuide that link to each other
Automatically re-centers the telescope during collimation so you can concentrate on the collimation adjustments and not have to re-center manually after each change
Acts as an autoguider with seeing effects partially removed from the error, so the "chasing of the seeing" is directly reduced
Locks onto a user-specified error frequency and corrects for it proactively, acting like a new level of periodic error correction that does not rely on indexing and can work at higher frequencies
Calculates centroid based on live view of stars using a very different algorithm than simple "center of gravity." To reach fainter stars, the frames may be stacked first for the effect of long exposures
Provides graphical output and logs of drift and periodic error in your mount, including the "noise" that can be hard to remove with PEC (Periodic Error Correction).
http://www.astrogeeks.com/Bliss/MetaGuide/

Am vazut imgini cu stele punctiforme facute cu telescoape mari:

http://www.flickr.com/photos/26671216@N02/6063159413/in/set-72157618612316465/
Explicatia pentru care un webcam prapadit produce fografii planetare foarte bune:
http://hkastroforum.net/viewtopic.php?t=8114
http://www.ast.cam.ac.uk/research/instrumentation.surveys.and.projects/lucky.imaging/latest.results/amateur.lucky.imaging

Un sistem "ieftin" in 2005 este accesibil si Romanilor in 2014?

"Although the details differ, the versions of LuckyCam have essentially the same optical layout – in almost all LuckyCam observations light from the telescope simply passes though a lens (to adjust the image scale) and a filter, before arriving at the CCD. No active optical elements are included, leading to a very elegant and cheap system. The evolution of the LuckyCam system was as follows:"
http://www.astro.caltech.edu/~nlaw/thesis/thesisch2.html

Exista azi camere 3LCCD the LLLCCD (Low Light Imaging without the need for an intensifier) accesibile?
http://www.ast.cam.ac.uk/research/instrumentation.surveys.and.projects/lucky.imaging/l3ccd.technology

Binevoieste vreun avansat sa comenteze, eventual daca aceste "noutati" sunt de mult vechi in Romania? ...sau cam care este stadiul astronomiei de amatori in Romania in relatie cu frontul ultimelor inventii si inovatii?