天王星 月惑星研究会 関西支部
Uranus Image 2004/09/15(UT)
Ralf Vandebergh(250mm Newton:ATK-2C)
Last night was very clear sky at my observing site,the seeing was reasonable,
I took new AVI's of Uranus this time using not only the ATK but also the ToUcam,the classic
Reason was to compare the results of both camera's.My ToUcam is an unmodified type,so I could
work only in videomode,and with the ATK in both the long-exposure and the videomode.The ATK
shows the best colors,the ToUcam had some problems so I show the image in black and white.
Obvious in the ToUcam image is the limb-darkening,which is very extreme on Uranus duo to
his gas atmosphere.We can see this also as a detail!
Most obvious in both images(ATK & ToUcam) is a strong polar flattening,which was already
visible in some of my earlier images taken in September.At first I thought it might be a camera
problem,but the ToUcam shows it also,and after inspectation of more AVI's taken in the
same session,I can only conclude that it is a real effect.
Belt structure on Uranus?
I was inspecting my latest Uranus images,after processing them on the brightest albedo part(the mid
of the disk)and was it really a structure wat I saw on my original image?
Thats exactly that part of the image what was overexposed in my first results of the same day,you know,
the image comparison of the ATK and ToUcam,with the polar flattening.Possible details couldn't
be visible on these images because I learn more and more that albedo feature imaging of Uranus is especially
a case of a right processing of the center of the Uranus disk,caused by the strong limb-darkening of Uranus,
just like we know from Jupiter.The key of succes might be the processing through a median strong but on
the right way used high-pass filter directly after contrast-adjusting and resampling of the original stack.
There is really a kind of belt-structure visible in this image processed on the central albedo of the disk,
and note: it is parallel to(same direction as)the polar-flattening exactly like it should be.
Thats a nice evidence of its reality,
just like the enlarging in its width to the limb,remember the classic Jupiter images on high contrast films
like technical pan,which showed this effect too.
[Ralf Vandebergh:neighbourhood of Maastricht Netherlands]