Newbie active planetary imagination?

[Tblog]

Created a stack of 6x120sec of Uranus.

Uranus_6frames_720s_WithDisplayStretch.png (266.73 KiB) Viewed 1520 times

(aggressively cropped here)
While I am certain it is Uranus, am I correct in asserting there are two moons (Titania & Oberon) visible? Or are they just background stars?
Stellarium indicates the moons have an apparent diameter of ~0.1 arcsecond.
Although my cmos camera has small pixels (ISA183 pro/2.4um), that resolution still seems way below the Dawes limit of my SW120ED (flattened) scope... Or am I just underestimating the power of stacking?
Sorry not directly on SharpCap point, but thanks for any insight.

[dbreit]

That depends.. When did you acquire this image data and were you using a Barlow??

I have not tried Uranus yet, but with my Stellarvue 130mm Raptor and the 2.4 micron pixels of my ASI178, especially when I use my 3X Barlow, would expect you could capture all four of Uranus's main moons..
The Moons being " 0.1" " - in this case - just means you can think of them as point sources.. i.e. stars..

Point being, I certainly get better resolution than theory suggests I should.. Good Refractors are hard to beat..

AutoStakkert3 will also increase your resolution when it stacks.. While I am a newbie, and like I said I haven't tried Uranus yet, but I think you might do much better w/ shorter exposures and more of them.. I shoot a "low histogram" with my 178 OSC, aiming for 35%.. When I stack in AutoStakkert, I then "Normalize to 90%"..

Mind you, I cannot "process".. at all.. (still learning) but this is one of my last Saturn images from last year..

20190816_04_49Z_Breit.png (134.35 KiB) Viewed 1507 times

and Jupiter..

20190816_05_23Z_Breit.png (185.98 KiB) Viewed 1507 times

I forget the exact numbers, and they are much brighter than Uranus, but Saturn was done at about 90ms per image from a 3 minute video stacking the best 30% and blending in 0% RAW..

Hope this helps and image more, as the seeing makes a huge difference..

Derek

[Tblog]

Thanks - and great photos!
My stack of Uranus (6x120 sec, phd2 guided) was taken Thursday 2/20/20, 4~4.5B sky, 2030m/6500' MSL. Clear sky, but I don't know seeing condition. No Barlow. I stacked with Sharpcap Pro, and hand-tweaked (within SC) the resultant stretched image.
I will research point-source v. optical resolution limits.

[dbreit]

I just meant that the Moons would appear to the camera as if they were stars.. So if Stellarium or whatever says they are magnitude 14 to would see them if can normally see mag 14 stars, though they have to be clear of the glare from the "bright" planet..
Looking in my favorite planetarium program, assuming that is actually Uranus, as I don't get an *exact* match, then that very well could be Uranus, TYC 0633- 0287-1, all four of Uranus's bright moons.. Ariel, Oberon, Titania, and Umbral.. Nice!

I will have to try that soon with my 130mm..

Derek

[dbreit]

Thanks for the kind words.. I think it is very very simple and anyone could do it.. My scope is exceptional.. Me?? Not so much.. )

Here.. This is useful..
https://astronomy.tools/calculators/field_of_view/
Select Field of View.. Select IMAGING.. Select your Target, such as Uranus, Select your scope, select your camera.. Click ADD TO VIEW.. That will shw you the FOV with your entire chip..
Now go back up and add in a 3X barlow.. and change the RESOLUTION to 800x600.. ADD TO View..
Scroll down and the image will show both FOV's.. Note the color of the larger one, and off to the right, pick the matching color and close it by pressing the "X".. Then you can see the FOV of your scope, your camera, with a 3X Barlow, and using a Region of Interest of 800x600 in SharpCap..
Use the Histogram and aim for 35-40%..
I am not sure about your camera, but for my 178, the maximum useful gain is 270.. (Everything above that is just digital gain, which only adds noise).. Find the equivalant of that for YOUR camera and use it always for planets and then adjust the histogram by adjusting exposure only.. It will definitely be below one second, I think.. Grab a .SER video with Sharpcap.. Try 5 minutes.. Stack with AutoStakkert.. Stretch and sharpen w/ RegiStax..
You *really* need a 3X barlow.. My 130mm scope is f/7 (910mm).. 3x barlow puts me at 2710mm focal length and is perfect for the 2.4micron pixels.. Works for me..

Derek