shadows on jupiter

[loakessg]

Hi.. I was trying out my webcam attached to scope last night and was capturing pictures of Jupiter. Now looking back over them I have found 2 with what looks like dark dots on them. Now I know you can see shadows of moons on the surface but these photos showed one at the bottom and then on another at about 9-oclock on the surface. Considering I was only taking pics for about 15 mins do these shadows really traverse Jupiters surface this fast or can I put it down to dodgy photos?

Sean

[RT65CB-SWL]

Jupiter's rotatation is 'fast' at about 9h50m +/-, (just think, you have departed LHR and arrived LAX in that time).

The speed of the Galilean moons took me surprise a few years ago after I received my C6/SCT. I could see one them emerging from from the far side. Left it for about two-three minutes, went back to it and it moved quite a distance in that short time.

[Astrosurf]

I've just done an image with Io's shadow and I was gobsmacked at how fast it moved. To find out if your dots were moon shadows or dust on the sensor, have a look here:

http://www.shallowsky.com/jupiter/

Alexxx

[michael.h.f.wilkinson]

The moons do move at a pretty impressive pace. Maybe you can post images, so we can see the results you got

[loakessg]

Thanks guys.. these are my images.. blurred and fuzzy as im lacking remote focus so please forgive the quality

[Freddie]

No shadow transits last night so most likely dirt on sensor.

[Astrosurf]

Must be dust. If you play Shallowsky Jupiter hour by hour you'll see the moons orbit Jupiter's equator. When I stacked my vids in DSS, and I watched DSS sort the frames and jumbled them up, the dust jumped around a lot but Io's shadow didn't.

[loakessg]

OK, thanks for the info. I need to invest in a laptop to capture images better. Using android tablet right now which isn't really suitable for connecting external webcam. Still, early days for me in imaging so its all experience.

[michael.h.f.wilkinson]

These dust bunnies can either be removed by taking flats, or carefully trying to keep the image of the planet away from these few spots during capture.

[Astrosurf]

Get one of these blowers (also on eBay - well, anywhere!) and give the sensor a quick few puffs while holding the sensor downward. Mind you don't touch the sensor of course!

http://www.amazon.co.uk/Hurricane-Cleaner-Cleaning-Minolta-Olympus/dp/B00MOLFPH6/ref=sr_1_1?ie=UTF8&qid=1425550174&sr=8-1&keywords=camera+sensor+blower

[loakessg]

These dust bunnies can either be removed by taking flats, or carefully trying to keep the image of the planet away from these few spots during capture.

What do you mean by flats? Seen this used a few times but don't know what it referzx to