The elusive ring(s) of Uranus. The brightest member of the ring system, the Epsilon ring, is clearly seen. Here I have an alternating overlay of ephemeris from SETI Uranus Viewer 3.1 (
https://pds-rings.seti.org/tools/viewer3_ura.shtml). Measuring the semi-major and semi-minor axis ratios, yields 32/28px or 33/30px depending on whether you use the inner and outer extent of the rings, respectively. This corresponds to a viewing (inclination) angle of 61°-65°. The expected value for the date is 64°.
I've experimented with many filters and imaging trains to catch these rings - it's always a battle between getting sufficient signal, and reducing the planet's glare enough for the rings to still be picked up. CH4 filters would extinct the globe significantly, but the 20nm bandpass is too tight to receive sufficient signal. Likewise, a luminance filter would give the best ring signal, but the albedo of Uranus itself is too high in the blue/green and so the rings are washed out by the planetary glare.
Here I settled on using the ProPlanet IR 742+, stacked with the Baader RG610 (to remove the blue leak of the 742). I started the session using the 2x barlow, but the first few stacks didn't show Miranda, so I dropped back to native focal length (1800mm f/4.4).
- 20 x 2-min videos stacked at 80% (32m). 45-msec, 300gain with ASI462MM. Good seeing.
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