Uranus

2021-10-31 Uranus
Image exposure:
Best 20% of 400 video frames
Image field of view:
1.7 arcmin (estimated)
Image date:
2021-10-31

My aim when imaging Uranus was to see if I could pick out any surface detail. That was a bit over-ambitious and of course I failed. Uranus does have some surface features, especially when you view it from a passing Voyager 2 spacecraft but most amateur images seem to show Uranus as a blank disc – bluish green with fuzzy edges, due to limb darkening.

There is another feature of Uranus that can’t be seen in amateur telescopes – its tenuous ring system. It has however been observed from large Earth-based observatories.

What about the satellites of Uranus, you may ask.

That’s yet another sore point. I have no doubt that the collection of bright objects around Uranus in the following uncropped (and deliberately over-exposed) image includes five of them: Oberon, Titania, Umbriel, Ariel and Miranda, which should all be easily visible at 13th to 15th magnitude – but identifying them has been too difficult. The next brightest is Puck (mag.19.2) and the remaining twenty-one are far too faint (mag. 20 – 25) to see in a modest amateur telescope.

So which five are they?

Uranus and moons.
Image: 2021-31-10, R.Powell.

There are five objects closely clustered around Uranus in this image which may or may not be the five brightest moons and several more background objects further out from Uranus, including one neat double star system (lower left).

Yet none of them seem to match the simulation which Cartes du Ciel generated for the exact same time.

So the bottom line is: no surface detail visible, no rings visible and satellites unconfirmed. šŸ˜Æ


EDIT: 10th November 2021

Solved!

Many thanks to my learned fellow blogger, Disperser, who persisted where I gave up. He correctly identified Titania, Umbriel, Ariel and Oberon. The fifth bright moon, Miranda has been obliterated by the enormously exaggerated size of the over-exposed Uranus. The other objects are background stars.

Disperser’s solution is in the comments section down below ā¬‡ā¬‡ā¬‡

Interesting facts about Uranus:

  • The axial tilt of Uranus is so great that only one polar region is visible. Currently we are looking almost face-on at most of the North Hemisphere. If you lived on the equator the Sun would currently appear to travel close to the horizon.
  • The next Uranian summer solstice will occur in 2030.
  • One day on Uranus is only about 17 Earth hours; but one orbit of the Sun takes 84 years. A Uraniun being would be lucky to even celebrate a first birthday!
  • Poor old Uranus is already the butt of far too many jokes about its name and now it is reported to smell like flatulence, according to this news item. Reminds me of the late Dave Allen’s humour.

Cosmic Focus Observatory

34Ā° S

Above us only sky….

Telescope:Meade LX-90 Schmidt-cassegrain refractor; 2000mm f/l @ f/10.
Optics:Astronomik light pollution filter.
Mount & Guiding:SkyWatcher EQ6-R Pro mount.
Imaging camera:ZWO ASI 071 MC cooled.

Images Ā© Roger Powell
šŸ™ƒ
I’m one of the founder members of Macarthur Astronomical Society

26 Comments

  1. Beautiful! I have never imaged Uranus. Nice work there! I did see Neptune for the first time about a week ago at our monthly outreach. Might still do a blog post on that. Neptune is well positioned here in the North right now. In contrast to Uranus which is really green, Neptune is definitely blue. Looks like a small blue dot in a 16″ scope.

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    1. Thanks. That is the most logical and obvious interpretation, however I cannot confirm it with the satellites’ simulated positions.
      Regards
      šŸ™ƒ

      Like

  2. Can you give me the exact time of the image? I presume the location from where it was taken won’t matter much. Also, a tighter crop of the image?

    I wanted to check what the simulation says versus your image.

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    1. The following extract from the image settings file:
      “TimeStamp=2021-10-31T12:43:02.4075110Z”
      I don’t know what the Z stands for… 12.43 UTC will do.

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    2. Hmm . . . I’m confused (maybe) and you need to excuse my ignorance as I never work with UTC.

      You’re 17 hours ahead of me. Are you giving me your local time or the UTC differential for your location? Your local time is UTC/GMT +11 (mine is -6).

      I’m not sure what you just game me. Was that 43 minutes after midnight at your location?

      Like

      1. No, neither of my telescopes produce inverted images. However, they are not necessarily “upright” (i.e. nearest horizon down) and the rotation can be oriented in any direction from 0Ā° to 360Ā°.

        Like

  3. OK, so, using Stellarium and assuming a different scale than might be initially assumed looking at the photo, this is what I can match very closely for the given time. I can even account for the double star that you mention, although it’s not named in Stellarium.

    of course, I could be way off base, but it was fun playing with this even if it turns out I’m playing in the weeds.

    Liked by 3 people

      1. You could be right. The scale is deceiving and the bloated over-exposure of Uranus is vastly more than I expected, hiding Miranda in the glow. The other objects must be background stars.

        Thanks for the inspired solution. Now I know what exoplanet hunters have to deal with!

        I have placed an edit with acknowledgement in the content of the blog post above ā¬†ā¬†ā¬†

        Liked by 1 person

  4. Wow, that second image makes Uranus look almost like a star with a solar system. I know I’ve heard about Jupiter just barely missing out on being another sun, but I imagine some of the other giants could have had a shot at that too.

    Liked by 1 person

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