Re: Images: IR Uranus and by daylight


<Thierry> ha scritto nel messaggio news:4522aa3e@xxxxxxxxxxxxx


Not sure that amateur scope can do bettert.
To compare to these images (end of page) with C14 and 250mm
http://www.astrosurf.org/luxorion/imagesgallery-planets-col.htm

Thierry


The (very good) images in the link are all taken in visible light, where
Uranus is a smooth and uniform blue-green ball (at least for small scopes);
Its aspect changes in IR light; longer is the wavelenght, greater is the
contrast of the south polar cap (until 2 microns); at I and J photometric
bands, the polar cap is quite bright, and the feature is recordable with
smaller telescopes (we have just to record the photometric changing, like
the Encke minima on Saturn, not necessarily the real detail, so it's not
very important the scope diameter, but the wavelenght and the camera used
(16bit cooled, with dark frames subtraction)). I used a CCD camera and 20"
exposures, in two different nights, and the images match perfectly.
We should also consider the images taken by Rolando Chavez::
http://www.buytelescopes.com/gallery/view_photo.asp?pid=9961&sg=1&page=2
(and the judgments of some important persons..see the link); those are
remarkable since are taken without an IR filter (thanks to a larger
telescope diameter maybe), and both (mine and Chavez's) match perfectly with
the Hubble pictures, and keck's:
http://www.ssec.wisc.edu/media/spotlight/Uranus.htm .

Daniele Gasparri
Perugia (Italy)
www.danielegasparri.com



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