7 replies to this topic

[Carolina Observer]

I received an email late Saturday morning (March 7th 2025) from expert visual observer, Jaakko Saloranta from Finland. He asked me if I’d ever seen Uranus without optical aid. Seems that Jaakko had a “lively” discussion with some reporters concerning the visibility of seeing Uranus naked eyes.

 

I have not seen Uranus using a telescope, and for sure not without any optical aid, but it’s now on my list of things to do this year.

 

March 8th 2025 Observation:

 

Now I know the moon is bright (71% illumination tonight (March 8th) but I’m going to at least use a small telescope tonight from my suburban backyard. to locate and see. I’ll be using a 4.5-inch f/8 Newtonian. I’ll then try the small 6 x 30 finder, and then my 7 x 21 Pentax mini-binoculars. And then if successful, I’ll attempt without any optical aid.

 

If you can’t see the planet without optical aid (especially at this time) why not attempt with a small telescope?

 

Observing report(s) as following in the link:

 

https://rogerivester...en-a-dark-site/

[wolf man]

   When I was younger I was able to see the planet without optical aid from a reasonably dark sky, say Bortle 4 or so, on a good clear night. Through my older eyes now it's kind of in and out with averted vision. It's in a relatively sparse star field now and that is helpful.

On a dark night it's still no trouble through 8x42's and 6x30's once I know where to look.

[Rick Runcie]

Uranus is not difficult, if you have as Wolfman stated, relatively dark skies (B-4) and can see 6th mag. stars being that Uranus is 5.7 magnitude.

When it's positioned lower in the sky it can be more difficult, but at its current position for Northern hemisphere observers it is not too difficult.

Like all fainter objects, good transparency and no moon are advantageous. Better seeing is a plus as well, but not as important transparency and darkness.

Best regards, Richard

[goodricke1]

Tried this a few years ago and am confident I saw it, yes mag 5.7 and Bortle 2/3. 

[Redbetter]

Since I know the general location of Uranus from year-to-year and it doesn't move that rapidly, I sometimes hunt it down naked eye early in the season, without looking up its position/coordinates first.  I compare to Uranometria along the ecliptic until I identify a 6th mag "star" in the sky that is not on the page.  Then I switch to the scope to confirm.  It can take a few guesses during that first session when it is low in the sky and I can't see the surrounding star field that well/fully, but about half the time I get it right on the first guess.

 

Typical sky conditions for me are Bortle 3 or a good Bortle 4 when I look for it naked eye.  Even on the nights from dark sites where I check the published position first, then look for it in finder, then the scope, I can still typically see it naked eye if I check.  I can't recall the last time I could not see it naked eye when I tried.

 

Of course this depends on the observer's personal NELM on a typical night and how high it is in the sky at the time.  If someone is having trouble exceeding 6.0 Venus is going to be rather difficult for them to identify naked eye.  I can usually reach around 7, sometimes as deep as 7.5 in darker/more transparent/steadier conditions.  I reached 8 on Mauna Kea but that was nearly three decades ago.

 

Presently it is "late in the season" for Uranus, with it low in the west by the time it is fully dark (and for me it doesn't help that this is the bright portion of my observing sites.).  Vesta will be better placed for the next few months, reaching about 5.6 mag by opposition on 5/2/25.  Observing Vesta night to night will be good practice for observing Uranus naked eye when it comes around again.  Vesta should reach about 0.6" diameter, so reasonable to resolve with large aperture and high magnification in very good seeing.  In this size range and even smaller one can tell the difference as being larger than a similar magnitude star, and lacking the first diffraction ring.  Vesta at opposition won't be much smaller than Titan's typical apparent size.

[Redbetter]

Last night (this AM) I observed Vesta from ~21.3 mpsas skies naked eye.  I had a rough coordinate position which I had plotted in Uranometria.  This was in a pattern with a 5.5 mag star in Librae, plus a 6.3 that was closer (to the N.)  With this and delta Librae I was able to determine that my naked eye position for ~6.4 mag Vesta was accurate because of where it fell on a line between them.  

 

I was able to confirm in the ST80 I used as a finder, as well as in the 20".   At 500x in the 20" I could clearly tell that Vesta at 0.5+ arc seconds diameter was resolved/non-stellar.  There was some apparent size despite the constantly moving disk (seeing), and there was no diffraction/interference pattern seen.  By comparison the 6.3 and 5.5 mag stars showed badly disrupted airy patterns with considerably smaller spurious disks shining through the messy pattern. The first dark ring/minima could be seen, although not continuous in the seeing.

Edited by Redbetter, 24 March 2025 - 06:56 PM.

[Galaxy Gazer]

I found Uranus not long after I got my 4-inch Maksutov-Cassegrain telescope, about a year and a half ago. It was the fourth planet I observed (after Saturn, Jupiter and Venus). Then came Mars and even Neptune. Neptune was a challenge but barely discernable as a more pale gray disc.

I was surprised Uranus didn't take as long as I expected. The first attempt was unsuccessful, but the following night I found it within an hour (I have a manual setup). After traversing a black sea of silver stars, finding the small lonely blue-green disc was a breathtaking solar system sighting. I believe I saw two moons too.

[Redbetter]

As soon as you see the disk you know.  I "rediscovered" Neptune this way in 2022 while star hopping to a galaxy.  I had forgotten that Neptune would be in that section of sky, so while doing the hop I noticed an ~8th mag "star" in the finder that didn't fit the pattern.  Wondering what it might be, I switched to the eyepiece of the 20" at 156x and was greeted by a steady, tiny pale blue disk.  I immediately realized what it was and a few seconds later identified Triton next to it.  At the time I wondered why it had not been discovered accidentally before 1846 (when it was discovered on purpose by astronomers looking for an object to associate with calculate orbital perturbations of Uranus.)

 

Neptune is becoming tricky to properly resolve by 4" of aperture, because it is approaching the size of the spurious disk for the aperture.  This makes the disk edge muted rather than sharply defined, so some comparison with stars of similar magnitude can be helpful.  Eventually one can learn to recognize a marginally resolved solar system body vs. a star.  And the color is not so apparent in small aperture because the image brightness is not great in small aperture at the sort of magnification needed to show a disk.  The eye has trouble with color discrimination as the brightness decreases.