Jupiter and Io

[MarkS]

Jupiter tonight using eyepiece projection on the Celestron C11 with the SPC900 webcam
400 frames at 0.2 sec stacked in Registax then deconvolution applied.

[Fay]

You never disappoint, Mark, really nice.

Fay

[Ian]

it is indeed, especially given Jupiter's altitude at the moment.

However, I'd say you've overcooked it a little on the deconvolution. Try applying a little less so that ringing disappears.

It's also good to see a moon in the same shot, you didn't cheat, by the look of it

[RobertM]

Nice one Mark, it's a difficult to catch any shots of Jupiter at the moment and even more difficult to process something from the blur - an awful lot of atmospheric disturbance can happen in 0.2s ! 

[Mike]

Nice one Mark. As Ian says it is overcooked andf looks like 3 out of register images of Jupiter on top of each other. But well done for getting the moon in the same shot (presuming you didn't cheat).

[MarkS]

Admittedly it is a bit overcooked - I was trying to extract as much detail as I could.

As for Io, there was no cheating!  I was pretty pleased to get it showing so well in the final image - before deconvolution it was just a faint blur.

[Ian]

go on, post a raw stack

[MarkS]

Sure!  I'll do it tonight (after OAS).

[Daniel]

Love the colour your showing on Io, is that 2 sets of exposures for moon and jaupiter or all in the same shot?

[MarkS]

Daniel, Io and Jupiter are in the same shot - it's not a composite image.

Ian, as promised, raw stacked image of 400 frames at 0.2sec is here:

[Ian]

it's certainly a bit murky. Could you stick up a link to the raw BMP? I've just had a play and I can show some fantastic jpg artifacts

[MarkS]

I'll post the 16bit tiff tomorrow then you can play with the full depth of data.

[MarkS]

The 16bit raw stack is here (1.8 Mbyte):

http://gallery.orpington-astronomy.org.uk/albums/userpics/10046/jup23jul400raw.tif

Good luck!

[Carole]

Daniel, Io and Jupiter are in the same shot - it's not a composite image.

I can't find Daniel in this image!!

[MarkS]

I had to deconvolve the Jupiter raw stack with a Gaussian having standard deviation of 10 pixels or 1.3 arcsec, since an arcsec is around 7.5 pixels in this image.

So, roughly speaking, a star at similar altitude (15deg) would have an FWHM of around 20 pixels  (2.6 arcsec).  Indeed, using the Io as a proxy for a star, the FWHM of Io is definitely round about 20 pixels.

[Fay]

That's quite funny for you, Carole!

[Carole]

Fay,

Thank goodness some-one got it, my jokes normally fall flat.

Carole

[MarkS]

Here's my final version, full size.  I can't tease out any more detail without producing nasty artifacts such as ringing.

Details as before: 400 frames of 0.2sec from SPC 900 webcam using 15mm eyepiece projection on the C11 giving an effective aperture of around F40.

Jupiter was approx 15 degrees in altitude.

[Rocket Pooch]

Hi Guys,

I think you are pushing it too far on the focal length, you will probably find it better with a smaller barlow, or no barlow at all, you will then get some detail out of it.  Somewhere in the gallery is a Jupiter at 15 deg I took a couple of years ago with a 10 inch scope I rememebr putting the 4x barlow in and the images we're like these, but with a 3x barlow everything got a lot better.  Why not give it a try with Jupiter half the size and try to get a full 90 seconds of AVI so you don't get rotational effects.

Chris

[Ian]

Pretty much completely disagree with you there Chris.

But with an assumption or two.

I would recommend imaging Jupiter (or any of the planets really) using all the focal length you can muster. Assuming that you can find, focus and track the planet well at that magnification. Oh, and get all of the objects in the frame (moons etc).

However, I think Mark's image would make a prettier image if the scale was reduced because I don't think there are any details in it that are helped by it's current scale.

The point is, if you make the decision before you start to reduce the focal length, and you get a period of fantastic seeing (yes, I know...) you can't take advantage of it. Reduce the focal length in the post-processing.

[Rocket Pooch]

Ok, one small point if you reduce the image and the scale you also increase the light and the signal to noise ratio as well.  If the seeing is bad then the object will move across the ccd less. 

But your more than welcome to disagree, my comments are only based on what images I gained not theory when Jupiter was very low at Headcord.

Obviously from a theory point of view, if we got good air stability and seeing and the scope was well collimated and we have good signal then it would be better, however looking at those images at least two of these things are missing.

Reducing down a fuzzy image end up with a smaller fuzzy image, not necessarily a better one.

I'll dig out the Jupiter I was talking about when I get home.  If someone is out and can see Jupiter give it a go at 2-4 meters, I would but I'm not about till the weekend.

Chirs

[Rocket Pooch]

Found it http://gallery.orpington-astronomy.org.uk/displayimage-5-13.html

And this was from home with crap seeing as well, http://gallery.orpington-astronomy.org.uk/displayimage-5-12.html

[Ian]

that is a good point, regarding the noise floor, and one more consideration, but in my experience, my 8" is capable of illuminating my sc3 well above the noise floor at F30 and above. Then if the detail's there, you'll get it, and if it's not, scale down until you get a pretty picture

I'd say the better image is the one taken at around F18, but it's hard to perform a comparison as seeing is still the limiting factor and would have been different.

I can't image Jupiter this year from home, it's too low, and I'm not planning on taking the 8" to DSC. Otherwise, I'd post some really compelling examples from this year  

Let's have a got at Saturn when it comes round again, see if we settle on a recommended approach.