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Contains: 
Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)

Jupiter gazes upon its Galilean moons

Technical card

Resolution: 1067x407

Date:June 7, 2018

Time: 19:45

Frames: 3000

Focal length: 3750

Seeing: 3

Transparency: 7

Locations: Home, Singapore, Singapore

Data source: Backyard

Description

This imaging run was originally intended to test a gamma setting hypothesis for Niall MacNeill; as it happens, it ended up producing some of my best data of the four Galilean moons yet!

Att Niall:

Ran a quick test run of your "mild gamma" hypothesis on Jupiter the other night. (Had to rush a little, clouded over shortly after this.)

Tried to keep similar settings during capture (aside from either having the gamma off or set to 40) but noticed that, when turning the gamma on, I needed a brighter overall histogram to still get signal from the moons. Therefore the histogram was around 60% for the "no gamma" capture, whilst for the "gamma 40" capture it was around 80%.

Rev B shows the results for "no gamma" (with selective processing/stretching of the moons).

Rev C shows the "gamma 40" data with the same wavelet processing - the gamma effectively pre-sharpens the data somewhat, so this ends up looking over sharpened at the same settings.

Rev D shows the "gamma 40" data with wavelets optimised for the data. (In hindsight, I over-sharpened Rev B a little as well ... don't have time to go back and fix this though.)

Rev E is a composite of the two images, which was annotated for the "final" version.

Tried as best as possible to process to an equivalent result - found this tricky to do! The difference is pretty marginal, but perhaps slightly less Gibbs effect in the "gamma 40" data. But for me this benefit is offset by:

1. Seems to be less contrast overall in the "gamma 40" data.

2. Following on from the observation during capture, having gamma on had a detrimental impact on the signal from the moons - dimmer overall, to the point where I could not bring Callisto back (even with stretching). So you'd probably want to capture both with and without gamma (or just without) if including the moons.

Ultimately, as per your earlier comment, Jupiter is maybe not the best target to test this on - Mars would be the ultimate test. But clouds have prevented any testing on that target so far. :)

Comments

Author

DMach
Darren (DMach)
License: None (All rights reserved)
1551
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Revisions

  • Final
    Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)
    Original
  • Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)
    B
  • Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)
    C
  • Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)
    D
  • Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)
    E

B

No gamma

C

Gamma 40, same wavelets

D

Gamma 40, adjusted wavelets

E

Composite image

Histogram

Jupiter gazes upon its Galilean moons, 





    
        

            Darren (DMach)