[Dennis]

Hello,

Straddling the midnight hour of 14th/15th September 2009, I recorded a series of images of Uranus and moons Oberon, Titania, Ariel & Umbriel spanning a period of 3 ½ hours. I recorded 8 sets of images, on the hour and every ½ hour between 10:00pm and 01:30am.

Celestron C9.25 F10 SCT with WO x2.5 Barlow at an Efl of 5875mm.
SBIG ST7 ccd camera, 20 x 10sec exposures for each of the 8 sets.
FOV 240x162 arcsec at 0.32 arcsec/pixel.
Brisbane, Qld, Australia.
10:00pm 14th Sept to 01:38am 15th Sept 2009 AEST (UT+10).

The sub frames were recorded in mono to produce registration frames giving the positions of the moons relative to Uranus for each of the 8 sets. A final RGB set was recorded at the end of the session for Uranus only.

The 20 sub frames in each set were blinked in CCDStack and the best frames (ranged from 4 to 7) were selected for aligning and combining to produce 8 registration frames for the positional data. Set 4 recorded at 11:30pm had the most usable frames so I used these to generate “pleasing” images of the moons that were then processed in CS3 with an LRGB image of Uranus to be used for generating the final animation frames.

I then manually generated the final animation frames in CS3 by overlaying the processed (pretty) LRGB Uranus and moons frame over each of the 8 registration frames, adjusting the positions of the processed moons to match their position on each registration frame. Due to the extensive processing involved, the brightness and positional data for the animation do not have the fidelity of the corresponding data on the unprocessed registration sets.

Approximate separations of moons from Uranus:
Uranus – Ariel 11”
Uranus – Umbriel 15”
Uranus – Titania 26”
Uranus – Oberon 40”

Magnitudes of bodies:
Uranus: 5.7m
Ariel: 14.4m
Umbriel: 15.0m
Titania: 13.9m
Oberon: 14.2m

Cheers

Dennis