Uranus

The Seventh Planet

Magnitude: +5.7
Apparent size:3.7 arc seconds.
Diameter:51,118 km (4 Earth diameters).
Distance:2825.2 million km (157 light minutes or 18.9 astronomical units).
Image date:2020- 11-25
Exposure:2 seconds

It was a moonlit night but the sky was clear so, despite the poor sky conditions, I decided to first check out the Moon and then have a look at Uranus.

Uranus orbits the Sun every 84 years, which means it moves slowly across the starry background at an average rate of just over one degree every three months.

It’s not much more than a dot in the image, approximately 0.001% of an angular degree in diameter as seen from Earth. When your target is only about twelve pixels across, it makes it very hard to produce a worthwhile image.

This shot was assembled from a 200 frame SER video file, stacking the best 20% of frames in Autostakkert, then cropped from 4944 x 3280 px to just 800 x 800 px – about 3% of its original size,.

I left my duo band Ha filter in the scope, although I wasn’t sure if that was a good idea or not. Probably not, because I seemed to get a bit more yellow and red than I would have expected.

Next time I shoot Uranus maybe I’ll over-expose it and look for its Moons. Five of the twenty-seven satellites are feasible targets between magnitude 13 to 15. The rest are too faint for my humble ‘scope but this is what they would have looked like:

Uranus and Moons, 25th November 2020 (Image credit: Cartes du Ciel)

Telescope Details

SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener; 2x Televue Powermate. ZWO Duo-band Hα (656nm) and OIII (500nm) filter.
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: EQMOD, PHD2, SharpCap, Gimp.
Observatory location: 34° South.

Images © Roger Powell

I’m a founder member of Macarthur Astronomical Society

11 Comments

  1. … resiting impulse to dig up Uranus jokes …

    Impressive you got something with your ‘humble’ telescope. I know it’s one of the planets one might be able to see with the naked eye if said eye is capable and conditions favorable . . . but not likely with my astigmatic eyes.

    Liked by 1 person

      1. Thank you.

      2. Yes, it’s brightness is roughly half a magnitude inside the limit for a very keen dark-adapted eye in a very dark country region with very good atmospheric conditions and a very precise knowledge of exactly where to look. 🤨

      Liked by 1 person

  2. Interesting composit. Years ago, (ok , not THAT long ago) thoughs of Uranus were generally without thought of any ‘moons!” It was just URANUS, an impressive blue/green little disk. But my notes indicate considering the sighting of “a faint, star-like” moon or two” although admittedly having no verification. M 🙂 Oh and is it ok to wish you a Happy Thanksgiving today? Probably not, as even here in the states, it’s really bizarre in this Covid -19 year! There is one thing we can give thanks for right now…however, …but this is not the time and place to elaborate. M 🙂

    Liked by 1 person

      1. Thirteenth magnitude through a good telescope with good eyes in a good place etc is quite feasible, so maybe you did see a moon or two.

      2. Thank you, I hope you enjoy your turkey.

      3. That time is coming – and when it does, the rest of the world will be celebrating it too.

      Liked by 1 person

      1. From my notes of that night, (3/8/63 (yeah I was 2 yrs. old…)) I seemed pretty nonchalant about confidence in sighting of one of the moons, and I really wasn’t looking specifically for one as Uranus was the target for the evening. It, (Uranus,) was “Impressive, as a beautiful bluish-green ‘ball'”. (That was through the 10″)
        As a side, I wrote: “I also looked for a moon or two but all I could see was a fairly bright star nearby. “I will try to look again tomorrow night…” Apparently, I didn’t follow-up. So I give myself a post observation – posthumous mark on this one. M 🙂 Our Turkey was good, but celebration seriously cut back with Covid-19 precautions. M 😦

        Liked by 1 person

  3. I got a look at Uranus a couple of weeks ago with my scope. It was very small but definitely not starlike. It had been years since I previously saw it. Thanks for sharing your view.

    Liked by 1 person

    1. In a telescope it really does stand out once you’ve located the right spot to look.

      I have better shots of Uranus taken previously with my Meade S/C. I don’t think my current set up is suitable for the outer planets.

      Like

  4. That would be cool to have a photo of Uranus with its moons! This is still pretty fascinating. I’m not sure if I’m imagining it, but it seems like I can see the faint trace of those topsy-turvy rings.

    Like

    1. The idea is planted in my mind. One day I will over-expose Uranus to see if I can get the brightest moons. The beauty of Uranus is its 98° axial tilt. The planet’s pole is more or less aimed towards us – and hence the orbits of the moons are too.

      Liked by 1 person

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