Titan: answer from Keck

here is the answer from Keck:

Rolando,

I think the markings in your images must be due to something other than
surface features on Titan, because they appear roughly the same in all three
colors. Titan's atmosphere is completely opaque to light from the surface
at wavelengths shorter than 600 nm. It might be possible to see surface
features in the red channel of your camera (with good enough seeing and high
contrast), but they would not show up in green and blue.

I suspect what you are seeing is sensitivity variations in the CCD which
detects the light in your camera. We have the same effect with the cameras
we use at professional observatories, and we calibrate it out by taking
images of a "flat" (twilight sky, or the internal surface of the dome
illuminated by a bright lamp), and dividing each image by this flat image.

Even if you aren't seeing surface features, these are very nice images of
Titan's cloudy atmosphere. They must have been taken on a great night,
because the limb appears sharp and well defined. Keep up the good work!

Antonin Bouchez

----------------------------------------------
Dr. Antonin Bouchez
W.M. Keck Observatory
- ---
http://astrosurf.com/demeautis