Jupiter 12/3/15

[kkara4]

First full stack with the QHY5L-II, fair seeing, Celestron Edge HD 925 @ about f/45.

RGB RGB RG composite and derotated in WinJUPOS, in total 4300 frames for RG610 filter, 2800 for Green filter and 2800 for blue filter. lost the final G and B sequences due to poor seeing.

Prior to the imaging session i used Metaguide / firecapture and a mag 3 star with RG610 filter for frankly easy in-focus airy disk examination in fair seeing, for collimation. I was off by about 1/32 of a turn on two screws, maybe less. The difference was so shocking i nearly fell off my chair. The sequences i pulled were far far better than even the night of good seeing back on 3rd march! Can't wait for good seeing night.

[oernulfs]

Very nice image. Lot of details. Good work!!

[ags_]

Well done Krishan a very nice capture & finding the perfect collimation settings then achieving excellent focus are the most important steps to maximise the image when the good seeing arrives, which it will.

cheers, Phil

[Camelopardalis]

Looks great mate, well done :thumbsup:

[kkara4]

thanks all was very happy with how it turned out - i know i can do better with better seeing.

I am hoping to capture some surface details on Ganymede now that collimation is good, but i know i will need good seeing for it.

will see what 15 knot jetstream on thursday treats me with :)

[astronobob]

That is an awesome image Krishan, dig them white storms, grs junior & other details everywhere, , :thumbsup:


Re:

Sorry if a silly question, but is this desciption to do with collimating the SCT, what the purpose of the airy disc in this application & what two screws were turned 1/32 turn ?
Thanx

[kkara4]

Thanks Bob!

Not a silly question, i completely forgot to put why i was examining the airy disk :lol:. Edited first post. For precise collimation you have to examine the in-focus airy disk. The two screws were two of the three screws on the secondary mirror. If you are even slightly off, the in-focus airy disk has an incomplete diffraction ring with a gap pointing to/opposite the screw that needs adjusting. Bad seeing sometimes makes this hard to see. RG610 filter, and metaguide which does live stacking of star images makes it surprisingly easy to get things perfect.

[astronobob]

Cheers Krishan, I suspected as such tho not 100% sure, sounds like an awesome method and thanx for the details, as Im hoping to set up my SCT for planetary experimentation down the 'hopefully short' track :thumbsup:

[kkara4]

very easy with QHY5L-II @ f/45 ish and metaguide and infrared filter and mag 3 ish star. in fact i didnt even need metaguide tbh, it just made it quicker because i didnt have to wait for good seeing for fleeting moments. you can very easily just use firecapture like i did initially.

i messed about with all sorts of other methods. artificial star is useless despite all the raving on the internet. DSLR is also near useless, too much dispersion/not enough resolution.

make sure you get Bob's Knobs - godsend.

[astronobob]

Can understand that, more than one way to skin a cat huh :thumbsup:
Like the idea of F45'ish too - tho haven't experience collimating at this level before - interesting times ahead :)