Jupiter and Ganymede Aug 11 to 12
Above is GIF animation from about a half hour before red spot transit last night (11:57 pm) to half hour after. Images acquired with Celeston Nexstar11 with Phillips Toucam 840K at cassegrain focus. Mostly cloudless sky but only fair seeing, about 5/10 at start but deteriorated to maybe 4. Animated gif created from 24 videos (1800 frames), each stacked and aligned with Registax4.
North up and east to the left in the image more or less. Shadow from Ganymede is the black spot in the north of rotating to the right. I think red spot jr is there too, off to the lower right of the great red spot. Appears to be another one to the lower left of the GRS, not sure what that is, I’ll have to do some checking..
September 2nd, 2008 at 6:26 pm
Hi Vern,it has been quite a while.Hope all is well?!.
That is a absolutely beautiful shot of Jupiter and as always…I am jealous..hahahha!.
No matter how hard I try,I can never get any true detail aside from solid looking cloud bands, even when my focus is almost spot on.Also,my images have a slight graininess which drives me crazy!
When I try to image Jupiter,I always use jpeg.Is their a different setting that will give me better detail?.For some reason I am drawn to jpeg even when I am told to use something different?!.What would you recommend for me to collect more detail without the grainy look?.
September 9th, 2008 at 9:14 pm
Hi Andrew,
All is well, I’m just real busy (a good thing, I guess).
Not sure what camera you are using but some have wide separation between adjacent pixels and have a rather strange grid look. In that case get a different camera. If by “grainy” you mean “noisy” then you just need to stack more images. I typically stack somewhere in the neighborhood of 1500 to 2000 images.
If you are sure your focus is good and you still don’t get any detail, it is almost always because the collimation is not good (in my case that is ALWAYS the cause). It doesn’t have to be off by much either. Laser collimators etc only get you within maybe 3 arc minutes. That is maybe good enough for visual but not for imaging — collimation needs to be within a few arc seconds.
I point at a bright star and then put on the webcam and defocus the star so that I get nice defocused ring. Adjust until it is as symmetric as conditions will permit. It takes maybe a half hour to do the first time, maybe a couple minutes with practice. At the high magnification of a webcam make only slight adjustments. Just enough to move the defocused ring around maybe half a field or less. Differences of adjusting as little as 5 arc seconds are very noticable in the resulting image. (a guestimate assuming the webcam has about 45 arc sec field on my scope).
Always collimate with the same setup that will be used for imaging. If you have an SCT don’t use a diagonal unless its absolutely necessary. Most diagonals are off several arc minutes (even good ones). Any movement of diagonal will destroy the collimation.
December 3rd, 2008 at 1:03 am
Nice to see your site back !! in 2003 i used to check it out when i was a beginner
. Never thought the next time I’d visit it i’d be an astronomer wow !!
I watch the moons of Jupiter travel across Jupiter whenever possible , fascinating.