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Your Most Interesting Ice Giant Observation

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#1 TimothyPleiades

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Posted 13 July 2020 - 06:37 PM

After viewing the planet voted most boring since 1781, Uranus (only kidding), for the first time last night, I'm curious what other people have had the chance to observe with Uranus and Neptune. Have you seen them through a large scope at an observatory? A once in a lifetime conjunction? Seen faint moons?

 

Through my 10" dob, Uranus is a bright, clear, off white featureless ball. Neptune is a bit dim, but a shade of blue I could never get tired of.

 

If you haven't been thrilled by them yet, on April 12, 2022, Neptune and Jupiter will have a conjunction with a separation of 6'. Should make for a good picture. Who turned Ganymede blue?

 

And Uranus and Mars will have a conjunction on Independence Day, 2026 (mark your calendars lol), also with a separation of 6 arc minutes.



#2 Allan Wade

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Posted 14 July 2020 - 06:40 AM

I like to observe Uranus and Neptune immediately after each other, to enjoy their different colour tones.

I find the moons of Uranus more entertaining than the planet itself.

 

Seeing Uranus naked eye is always a treat.



#3 Redbetter

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Posted 15 July 2020 - 01:26 AM

Note that the April 22 conjunction occurs with the planets only about 28 degrees from the Sun and low along the ecliptic, so for most in the northern hemisphere by the time they are high enough in the sky for viewing it will be full daylight.  The 2026 Mars conjunction will be somewhat higher in the morning sky before sunrise.

 

I normally find Uranus naked eye, starting with some general idea of what section of the sky it is in, looking at 6 mag stars on a chart near the ecliptic, then searching for one in the sky that doesn't belong. Pointing to it with the scope confirms...or not.   Once found the first time during the season, I can usually find it quickly for the remainder of the season.  

 

One of the best views I had of Uranus was early on in a 17" scope.  The seeing was steady and I immediately located the 4 brightest moons.  I had been seeing only two of them in my 8", so this provided confirmation as well as adding two others I had not seen before. 

 

Like Allan, I enjoy the color contrast of viewing these two back to back.  


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#4 TimothyPleiades

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Posted 16 July 2020 - 10:49 PM

Note that the April 22 conjunction occurs with the planets only about 28 degrees from the Sun and low along the ecliptic, so for most in the northern hemisphere by the time they are high enough in the sky for viewing it will be full daylight.  The 2026 Mars conjunction will be somewhat higher in the morning sky before sunrise.

 

I normally find Uranus naked eye, starting with some general idea of what section of the sky it is in, looking at 6 mag stars on a chart near the ecliptic, then searching for one in the sky that doesn't belong. Pointing to it with the scope confirms...or not.   Once found the first time during the season, I can usually find it quickly for the remainder of the season.  

 

One of the best views I had of Uranus was early on in a 17" scope.  The seeing was steady and I immediately located the 4 brightest moons.  I had been seeing only two of them in my 8", so this provided confirmation as well as adding two others I had not seen before. 

 

Like Allan, I enjoy the color contrast of viewing these two back to back.  

Yeah, it's certainly not optimal for those conjunctions. I'm glad to hear you could see 2 moons of Uranus in an 8", as I haven't seen any in my 10" yet. What magnification did it take to see the first two?



#5 NorthernlatAK

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Posted 17 July 2020 - 12:30 AM

In oct of 2018 I had just received my
gso 2.5× 3 element barlow (more like 2.1×) and decided to test it on Uranus after looking at the moon and seeing I had a steady sky. I had my fairly new 8" intelliscope and found Uranus at low power. Then I popped in a 9mm t1 nagler that was also new to me with the barlow, for about 266×. Low and behold, the tiny disc was showing two colors! 2/5 of the disc was white while the rest was a pale green. The white was one of the poles, but tilted on its side. The difference in color was very subtle but felt real. At first I thought maybe I imagined it, but then a few images started coming in on this forum, and also one from Hubble iirc. They showed the white tilted pole and my observation was not imagined! Fond memory and I haven't seen it like that since.

#6 David Knisely

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Posted 17 July 2020 - 12:51 AM

The largest scope I have seen Uranus in was a 24 inch Starmaster.  The view was pretty similar to what I see in my 14 inch Dob: Uranus11-16-11BlackMamba.jpg


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#7 Stargazer3236

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Posted 18 July 2020 - 11:38 PM

I got images of Uranus and Neptune last Night:

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#8 Redbetter

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Posted 19 July 2020 - 01:31 AM

I'm glad to hear you could see 2 moons of Uranus in an 8", as I haven't seen any in my 10" yet. What magnification did it take to see the first two?

 

It was somewhere between 226x and 290x nominal in the SCT from what I recall.  It wasn't the first time I had seen one of the moons, but it was the first time I had seen two at the same time.  I was catching one periodically at what was probably a Bortle 3 site at the time.  The other site where I saw two was probably a good Bortle 2 back then.  

 

The key is often good seeing assuming the site is rural.   Good seeing does two things for revealing faint moons:  it allows near constant good focus that increases apparent contrast of the moon itself against the background, and it reduces the out of focus glare from the planet.   The difference in seeing is apparent in moons and stars that are approaching the averted vision threshold.  In good seeing the objects are stellar, while in poor seeing they appear as tiny out of focus blurs, at times seeming semi-stellar with a brighter inner portion. 


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#9 Rutilus

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Posted 19 July 2020 - 03:01 AM

When the seeing is good, I have observed the moons Titania and Oberon at 400x with my

6 inch f/8 achromat refractor.

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#10 Redbetter

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Posted 19 July 2020 - 05:49 AM

From a post I made last November:

 

In October I did a check with an 8" off-axis mask on the 20" Dob at a dark site (21.3 MPSAS at the time.)  I first located the four largest moons with full aperture, then put on the 8" mask.  Seeing was about 5/10 Pickering for 8" aperture at the time.  

 

At 278x Titania and Oberon were readily visible.  At 357x I was detecting a brighter spot in the glare surrounding the planet.  This was Ariel, and 500x provided sufficient image scale to separate this very faint but bloated spot from the glare.  In addition I realized I could also detect Umbriel preceding the planet.  Umbriel was visible about 50% of the time in averted vision and could be held at moments, so there was no ambiguity about it.

 

This was in mediocre (but decent for here) seeing that was quite variable that night.  I would rate it more as passable than good for this type of observation.  This wasn't one of the darker nights at this site either, actually this was toward the brighter end, although sky darkness is less of a factor for seeing moons like this (once the sky is darker than ~21 MPSAS) than the glare of the planet which becomes the major limitation...along with seeing which contributes mightily to the apparent glare.

 

I had no idea I could pick up Ariel and Umbriel with 8" (unobstructed).  However, I did so after seeing them first with the full 20" aperture, so I knew where to look, particularly for Umbriel. I went well past magnification I typically would use for an 8" for planetary or these seeing conditions--in this case to provide image scale for separation alone.  My SCT with ~34% obstruction was typically limited to about ~300x for planetary detail in excellent seeing.  

 

There is little doubt to me that Titania and Oberon would have been visible with a 6" mask on the 17 year old reflector.   Unfortunately, I had left my 6" mask at home that night.   

 

Actual good or excellent seeing would make such observations more straightforward.  



#11 Scott99

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Posted 19 July 2020 - 12:16 PM

Here is a list of Uranus moons - basically four are 14nth magnitude and one is 15:

 

https://www.theceles...anus-moons.html

 

Triton on Neptune is 13.5 and the others are much dimmer.  So I guess you view these and then confirm w/ online charts to rule out dim stars?

 

Interesting, Jupiter's Amalthea is 14nth magnitude and has wide separation, I wonder if some of us have seen it without knowing?  I definitely want to try for Phobos & Deimos this year too (11nth and 12nth magnitude)


Edited by Scott99, 19 July 2020 - 12:18 PM.


#12 Redbetter

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Posted 19 July 2020 - 05:56 PM

Some of those magnitudes in the link are considerably off, and seem to be a mix of mean JPL magnitudes and some other source.   Miranda is a 16th magnitude object and Umbriel is essentially 15th magnitude.

 

Before getting to the relative magnitudes it is important to remember that there is some eccentricity to Uranus' orbit so that its distance from the Sun over an orbit ranges from ~18.3 to 20.1 AU.    Of course it moves slowly, and it is presently rather closer to aphelion than perihelion.  Around opposition this year it will be about 19.8 AU from the Sun and something like 18.8 from Earth.  This is worth a couple of tenths of magnitude.

 

There is some variation in the stated "mean opposition" magnitude for the Uranian moons, albedo and such.   JPL's values seem fairly consistent except for Miranda which they show as a few tenths brighter than some other sources (including an older NASA doc.)  Miranda was discovered photographically using the 82" at McDonald Observatory in 1948 when it was closer to perihelion.  If it was as bright as indicated it would have been discovered sooner.

 

Miranda is a dim 16th magnitude object at its present distance.  At opposition this year WINJUPOS and Stellarium indicate it will be about 16.4 to 16.5 magnitude.  If it was brighter than 16 it would be far less difficult to detect visually.  Umbriel is given as 14.9 to 15.0.  


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#13 Allan Wade

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Posted 19 July 2020 - 05:56 PM

Interesting, Jupiter's Amalthea is 14nth magnitude and has wide separation, I wonder if some of us have seen it without knowing?  I definitely want to try for Phobos & Deimos this year too (11nth and 12nth magnitude)

One of the research papers I read suggested since Edward Barnard’s discovery of Amalthea in 1892, that possibly only 20 people have ever seen it. So I’m pretty sure no one has accidentally ever seen Amalthea.

 

I spent two years trying to see Amalthea in the 32” without success, so a lot of eyepiece time, perhaps nearly 100 hours. I finally saw it last month for a 15 minute window when it was at maximum elongation from Jupiter. The great difficulty is the 17 magnitude difference between Jupiter and Amalthea, so Jupiter is about six million times brighter.

 

I’ve seen Phobos and Deimos many times and they are about 13 or 14 magnitudes fainter than Mars, and in my experience almost infinitely easier to see than Amalthea. I really hope you get to see those two later in the year.

 

https://www.cloudyni...ea-observation/


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#14 Allan Wade

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Posted 19 July 2020 - 06:05 PM

I’ve not come across a report yet of anyone observing Miranda. 



#15 Dave Mitsky

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Posted 22 July 2020 - 09:02 PM

The largest aperture that I've observed Uranus with has been, to the best of my recollection, 24 inches.  IIRC, I was able to see four of the five major Uranian satellites.

 

https://skyandtelesc...oons-ofuranus/#

I've observed Uranus many times with smaller apertures, the 17" f/15 classical Cassegrain at the Naylor Observatory, for instance.

When I visited the Griffith Observatory in 2012, I saw Uranus through the 11.8" f/16.7 Zeiss achromatic refractor housed in one of the domes.

http://www.griffitho..._telescope.html
 

I've also observed Neptune and Triton many times with the 17" f/15 classical Cassegrain over the years.

 

https://skyandtelesc...triton-tracker/

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