Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

Locating and Observing Uranus and Neptune

Dob Planet Observing
  • Please log in to reply
33 replies to this topic

#1 Henry Decker

Henry Decker

    Lift Off

  • -----
  • topic starter
  • Posts: 24
  • Joined: 27 Jun 2021
  • Loc: Ogden, Utah

Posted 16 September 2021 - 07:35 PM

Hello everyone!

 

The past few nights I have tried to find and view both Uranus and Neptune (both unsuccessful) so I have come here asking for help. I have an 8" dobsonian and I have read from others that they can be seen very easily with this size of scope, but I haven't had any luck. Is it just that I'm too inexperienced? I understand that I won't be able to see details in them, and I might not even be able to see colour but I would like to at least see them as a disk. Does anyone have any tips for locating these targets?

 

P.S. please keep the Uranus jokes down, I'm really trying to learn about this...


Edited by Henry Decker, 16 September 2021 - 08:05 PM.


#2 Achernar

Achernar

    Voyager 1

  • *****
  • Posts: 12,312
  • Joined: 25 Feb 2006
  • Loc: Mobile, Alabama, USA

Posted 16 September 2021 - 07:57 PM

If all you have is a printed chart for the date you wish to look for them, you can find them with a 50mm finder scope. Uranus is visible to the unaided eye from a dark site, and through a finder it's very obvious as a teal or turquoise looking star with a magnitude of 5.7 or so. At 50 or 60X it will show an obvious but small disk. Neptune is much dimmer at magnitude 7.8, and far smaller. Point the telescope at the spot where the chart indicates it will be, and use at least 100X to slowly scan the area. Neptune is more ice blue in color and will show a very small disk while the background stars remain pinpoints. It goes without saying that trying to find it during bad seeing is pointless, so if the stars are twinkling furiously or a strong weather front just passed through, wait for a better night. In either case, you can star hop your way to these planets, they usually are near some convenient star to use as a starting point for your search. They move slowly against the background stars, so if you see them tonight, they will still be in the same general areas a week later. Once you find them, if you have access to a 10-inch or larger telescope, you could track down their largest moons Oberon, Titania and Triton.

 

Taras


  • Gert K A, therealdmt and danyal123 like this

#3 MikeHC8

MikeHC8

    Mariner 2

  • -----
  • Posts: 205
  • Joined: 09 Dec 2018
  • Loc: San Diego

Posted 16 September 2021 - 08:06 PM

I am not a expert but your going to need a star chart to locate Uranus, it appears to only have around 6th magnitude starts near it, it appears to be 15 degrees from Pleiades, go south west from this object, you should see Pleiades with your eyes.  It took me about lot of time before I could see this planet for the first time, just relax and enjoy your time in the skies.  Neptune may be a little easier for you, fine Jupiter and make a fist, from Jupiter look at Saturn and make a imaginary line from these two planets going North East and you should find the area with 2 and 1/2 fist, each fist is about 10 degrees.  Again this could take a few attempts over weeks but once you find it on your own, you'll never forget.  You now will be a expertsmile.gif   I use sky safari plus which helps me a lot to locate things, it's a small investment for a life time hobby.



#4 rblackadar

rblackadar

    Mariner 2

  • *****
  • Posts: 276
  • Joined: 01 Mar 2019
  • Loc: Northern California (Mt. Tam)

Posted 16 September 2021 - 08:50 PM

The past few nights I have tried to find and view both Uranus and Neptune (both unsuccessful) so I have come here asking for help. I have an 8" dobsonian and I have read from others that they can be seen very easily with this size of scope, but I haven't had any luck. Is it just that I'm too inexperienced? I understand that I won't be able to see details in them, and I might not even be able to see colour but I would like to at least see them as a disk. Does anyone have any tips for locating these targets?

Seeing these planets isn't the issue, it's finding them. Currently, neither is very close to any bright stars that make for convenient star-hopping. So, it's not surprising that you've had a hard time of it.

 

If you're not already using a program like Stellarium, might I suggest that you try that out? The standard (free) download includes an "Ocular" feature that presents the exact view you should expect to see through your eyepiece. Study that view -- it's how you will know when you get to the right place. As for getting there, check out various online tutorials and forum threads devoted to star hopping using Stellarium or similar tools. It takes practice, and I'm still learning!

 

You might also consider scanning with binoculars -- Uranus will look like a star, but it will at least be visible, and you can use the binocs to plan how to do your star-hop with the big scope.

 

For Neptune, my strategy would be to find the dogleg of three stars at the eastern knee of Aquarius, and hop from there. Binoculars might be helpful to get you oriented here as well, even though you will probably not be able to pick out the planet with them.



#5 Bean614

Bean614

    Vanguard

  • *****
  • Posts: 2,176
  • Joined: 05 Nov 2015
  • Loc: Mass.

Posted 16 September 2021 - 08:56 PM

I would use an Astronomy App, like SkySafari, instead of a paper chart.  Planets move at different rates, and sometimes directions,  than do Stars, which move around the North Celestial Pole at the 'Sidereal' rate, from East to West.

Apps will much more easily show the Exact position for any Planet, in relation to an easy to find bright star, or constellation,  at ANY given moment, on ANY night, which makes locating Planets, even Pluto, very simple in your 8 inch dob.


  • sevenofnine likes this

#6 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 16 September 2021 - 08:59 PM

Here are the sections on Uranus and Neptune from my September Celestial Calendar at https://www.cloudyni.../#entry11333456

 

Uranus lies halfway between the fifth-magnitude stars Omicron and Sigma Arietis at the beginning of the month. By the final day of September, it is located within 25 arc minutes of Omicron. The waning gibbous Moon passes about one degree southeast of Uranus on September 24th. Visit http://www.nakedeyep....com/uranus.htm for a finder chart. Five of the brightest Uranian satellites (Miranda, Ariel, Umbriel, Titania, and Oberon) can be located using the Sky & Telescope interactive observing tool at https://skyandtelesc...moons-ofuranus/

 

Neptune is located almost five degrees east of the fourth-magnitude star Phi Aquarii as September begins. The ice giant planet lies less than four degrees east of the star at the end of the month. It passes within 1.5 arc minutes of a sixth-magnitude star on September 23rd. Neptune subtends 2.3 arc seconds, shines at magnitude +7.8, and lies at a distance of 4.0 light hours when it reaches opposition on September 14th. The Full Moon passes less than four degrees southeast of Neptune on September 20th. See http://www.nakedeyep...com/neptune.htm for an online finder chart. An article on Neptune complete with a finder chart appears on pages 48 and 49 of the September 2021 issue of Sky & Telescope. Triton, Neptune's brightest satellite, can be located using the Sky & Telescope interactive observing tool at https://skyandtelesc...triton-tracker/

 


  • Illinois, sevenofnine, viking725 and 1 other like this

#7 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 16 September 2021 - 09:04 PM

Keep in mind that even at 200x Neptune is quite small when seen in an eyepiece.  While very small in apparent size, the planet does exhibit a fairly noticeable blue color.  I usually observe Neptune (and Triton) at 462x with the Naylor Observatory's 17" f/15 classical Cassegrain if the seeing allows that much magnification. 



#8 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 16 September 2021 - 09:15 PM

Here's a screencap (click to enlarge) from Stellarium showing a wide view of Neptune's position is Aquarius from my location when the Moon is out of the way on the night of October 6th/7th at 4:00 UT (12:00 a.m. EDT).

Attached Thumbnails

  • Neptune 10-6-21 Wide Stellarium.JPG

  • SteveG likes this

#9 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 16 September 2021 - 09:17 PM

Here's a close-up view.

Attached Thumbnails

  • Neptune 10-6-21 Stellarium.JPG


#10 CBM1970

CBM1970

    Vostok 1

  • -----
  • Posts: 114
  • Joined: 09 Jan 2021
  • Loc: Southern Maine

Posted 16 September 2021 - 09:29 PM

For the first time ever, I successfully found Uranus about a week ago. It was my second serious attempt to find it.

 

I carefully starhopped to it, using the free mobile phone version of Stellarium. I find the app (and this version of the app specifically) very useful for starhopping. It only shows stars down to magnitude 8. This is what I'm going to see easily in the scope, so I am able to quickly identify small asterisms and star patterns without being misled/confused by the much fainter stars that show up in better versions of Stellarium.

 

For the time of night (and also at the very moment I type this) Uranus is almost exactly 12 degrees directly "down" from Hamal - the brightest star in Aries. That meant I was only moving in one direction from my staring point.. I located Hamal fairly quickly with unaided eyes and got it in the scope. Then I slowly made my way down 12 degrees, matching up stars to what was shown on Stellarium on my way down. I eventually found Uranus. Fortunately, it is part of a horseshoe shaped pattern of stars that just fit into my field of view with a 25mm plossl (my widest field eyepiece at about 1.8 degrees). Once I had a positive ID, I started increasing the magnification.

 

Unfortunately, the night I did this was a night of miserable seeing (2/5 or "poor" on Astrospheric). Stars were starting to blur at a little over 100x, and anything over about 125x was useless. As a result, I could not resolve Uranus as a disk in the eyepiece or in my smartphone photos (which were actually much worse than the view through the eyepiece thanks to the seeing). 

 

Still, I was excited in that at least I knew I'd found it. It will be that much easier to find again on a night of favorable seeing.

 

Of course, the way I found it was something I've practiced a lot and that works well with my equipment and conditions (meaning my scope, my widest field eyepiece, the version of Stellarium that I use, my eyesight, and the view from my backyard). You may find other methods that work better with your equipment and conditions, but you will find it eventually.

 

When you do, it will probably be a great feeling. It was for me. Neptune is still on my to-do list...

 

Good luck, and happy hunting!


Edited by CBM1970, 16 September 2021 - 09:36 PM.

  • Gert K A likes this

#11 Zavijava

Zavijava

    Explorer 1

  • -----
  • Posts: 76
  • Joined: 27 Jul 2020
  • Loc: 37N 122W

Posted 16 September 2021 - 09:42 PM

I second Bean614's suggestion to use an astronomy app instead of a static finder chart. I've easily found Neptune twice in the past two weeks with a far smaller scope than yours (StarBlast 4.5), guided by Stellarium Plus. Phi Aquarii is a good starting point, or you can start from the Psi triplet, which is distinctive enough that you can be sure you got it right, and go up from it to Phi. Neptune is now only about 4.5 degrees from Phi, and there are enough stars on the way to guide you. Make sure you set the app's magnitude limit so that it doesn't shows the stars you can't see, and zoom and rotate the device to match the eyepiece view. And of course use the longest FL eyepiece you have for navigation.


  • ShaulaB likes this

#12 hcf

hcf

    Viking 1

  • -----
  • Posts: 894
  • Joined: 01 Dec 2017

Posted 16 September 2021 - 09:56 PM

What finders do you have with your Dob?

 

With a  Dob, you need a RACI magnifying finder and a Telrad or RDF to make it easy to find objects in the night sky. The Telrad/RDF is used to get to neighborhood of the target,  and the RACI finder from there on.

 

With these finders, any planetarium app/starchart should be enough to find the planets. I prefer Stellarium on a laptop/desktop (free) or Sky Safari Pro (paid) on Android. Field Of View Circles drawn by the app corresponding to your scope/eyepiece view will help.


Edited by hcf, 16 September 2021 - 10:01 PM.

  • EricSi likes this

#13 therealdmt

therealdmt

    Viking 1

  • *****
  • Posts: 999
  • Joined: 05 Mar 2015
  • Loc: 35° N

Posted 17 September 2021 - 03:15 AM

I found (with the help of a sky-watching app on my smartphone) Uranus just with small 12x25 roof prism binoculars in Bortle 7 skies, and then again with my 4" telescope later in Bortle 8 skies. In binoculars, it'll be the only teal-colored star in the area it's supposed to be in. In my telescope, it was perceivable as a disk. One could get a bit of a "planet-y" feel from it, but it was getting dim when I tried really cranking up the magnification to see more.

 

Frankly, after that above experience with Uranus last year, I didn't bother carrying through with my original plan to then go after Neptune, and haven't felt particularly compelled to yet this year either (and Neptune has been my "favorite planet" grin.gif  since the Voyager flyby days). Still, now that you mention it, Uranus could be worth a re-visit, and I would definitely like to see Triton some day (along with Neptune), but Triton will take a different (bigger) telescope than I currently own


Edited by therealdmt, 17 September 2021 - 04:35 AM.


#14 rhetfield

rhetfield

    Surveyor 1

  • *****
  • Posts: 1,978
  • Joined: 14 Aug 2019
  • Loc: Suburban Chicago, IL, USA

Posted 17 September 2021 - 07:56 AM

Degree circles are your best friend with a dob.  Especially in light polluted skies.  I use sky safari on a tablet to get the coordinates and see what the surrounding star field is like.

 

https://www.cloudyni...degree-circles/

 

My experience is that both planets pretty much look like smaller/dimmer stars and that one almost has to go by color and compare the star field.  I usually don't know for sure until I take the suspected planet out of focus.  If it turns into a blob, it is the planet.  If it shows diffraction rings, it is a star.

 

It generally needs to be over 300x magnification to start looking like a disk.  Even then, it will be small.  Like one of Jupiter's moons small.


  • sevenofnine, FoxIslandHiker and Henry Decker like this

#15 Tony Flanders

Tony Flanders

    ISS

  • *****
  • Posts: 20,049
  • Joined: 18 May 2006
  • Loc: Cambridge, MA, USA

Posted 17 September 2021 - 08:32 AM

Degree circles are your best friend with a dob.  Especially in light polluted skies.


I must admit that I have never used degree circles on any of my Dobs. Every time I contemplate it, I'm daunted by the problem of implementing them and just fall back lazily on star-hopping instead.

So what I'm saying is just a hunch, not from real experience. My guess is that for the average newbie trying to find Uranus -- and much more so for finding Neptune -- degree circles are likely to hurt more than they help. It's a matter of accuracy.

Once you know what Uranus looks like through a telescope, it's pretty easy to identify by its color, which is quite unlike any star's color. But I doubt that a complete newbie would be able to recognize Uranus by its color alone.

To do that you either need to know precisely where within the field of view Uranus lies or else use enough magnification to show it as a disk. Which for a newbie, is probably quite a lot of magnification, maybe even as high as 200X. And placing an object inside the FOV at such high power requires more precision than you can get from any normal setting circles.

 

Neptune has the same issues but worse, since it appears quite a bit smaller than Uranus and much, much fainter.

 

When the original poster said that he "tried to find and view" these planets, I'm curious exactly what he did. One thing I can guarantee -- you definitely won't find either planet just by vaguely sweeping over the right part of the sky. In fact, you can't find much of anything that way. Much worse than the proverbial needle in a haystack.


  • ArizonaScott, Jon Isaacs, SteveG and 3 others like this

#16 rhetfield

rhetfield

    Surveyor 1

  • *****
  • Posts: 1,978
  • Joined: 14 Aug 2019
  • Loc: Suburban Chicago, IL, USA

Posted 17 September 2021 - 09:10 AM

I must admit that I have never used degree circles on any of my Dobs. Every time I contemplate it, I'm daunted by the problem of implementing them and just fall back lazily on star-hopping instead.

So what I'm saying is just a hunch, not from real experience. My guess is that for the average newbie trying to find Uranus -- and much more so for finding Neptune -- degree circles are likely to hurt more than they help. It's a matter of accuracy.

Once you know what Uranus looks like through a telescope, it's pretty easy to identify by its color, which is quite unlike any star's color. But I doubt that a complete newbie would be able to recognize Uranus by its color alone.

To do that you either need to know precisely where within the field of view Uranus lies or else use enough magnification to show it as a disk. Which for a newbie, is probably quite a lot of magnification, maybe even as high as 200X. And placing an object inside the FOV at such high power requires more precision than you can get from any normal setting circles.

 

Neptune has the same issues but worse, since it appears quite a bit smaller than Uranus and much, much fainter.

 

When the original poster said that he "tried to find and view" these planets, I'm curious exactly what he did. One thing I can guarantee -- you definitely won't find either planet just by vaguely sweeping over the right part of the sky. In fact, you can't find much of anything that way. Much worse than the proverbial needle in a haystack.

I can generally get within my 2 degree field of view with degree circles provided my tablet/phone app is updated for date/time.  Once there, I do have to try to match the stars to the chart - I still haven't got the chart dialed in to correctly show what is actually visible.  Right now, star hopping to Neptune would have me starting at Jupiter, as that is currently the closest thing to Neptune that is visible naked eye in my skies at midnight.



#17 Jon Isaacs

Jon Isaacs

    ISS

  • *****
  • Posts: 95,294
  • Joined: 16 Jun 2004
  • Loc: San Diego and Boulevard, CA

Posted 17 September 2021 - 09:46 AM

I must admit that I have never used degree circles on any of my Dobs. Every time I contemplate it, I'm daunted by the problem of implementing them and just fall back lazily on star-hopping instead.

So what I'm saying is just a hunch, not from real experience. My guess is that for the average newbie trying to find Uranus -- and much more so for finding Neptune -- degree circles are likely to hurt more than they help. It's a matter of accuracy.

Once you know what Uranus looks like through a telescope, it's pretty easy to identify by its color, which is quite unlike any star's color. But I doubt that a complete newbie would be able to recognize Uranus by its color alone.

To do that you either need to know precisely where within the field of view Uranus lies or else use enough magnification to show it as a disk. Which for a newbie, is probably quite a lot of magnification, maybe even as high as 200X. And placing an object inside the FOV at such high power requires more precision than you can get from any normal setting circles.

 

Neptune has the same issues but worse, since it appears quite a bit smaller than Uranus and much, much fainter.

 

When the original poster said that he "tried to find and view" these planets, I'm curious exactly what he did. One thing I can guarantee -- you definitely won't find either planet just by vaguely sweeping over the right part of the sky. In fact, you can't find much of anything that way. Much worse than the proverbial needle in a haystack.

 

I have experimented with a digital level and a form of an azimuth circle from my light polluted San Diego backyard.  I found to be effective for objects that could be identified as the object in a lower power eyepiece as the object of interest.

 

With objects like Uranus, Neptune or binary stars that require higher magnifications, to identify, I found some star hopping is required to make a positive identification. Personally, it's just easier to star hop from the beginning.

 

From my light polluted backyard, to find Neptune, I would use Safari, I would start out binoculars, either 7x35s with a 9.3° field or 10x50s with a 6.5° field. The 7x35s would probably be best.

 

I would start with Jupiter, it's two fields of view to lambda Aquarii. I would identify phi Aquarii and psi 1,2,and 3 Aquarii. I could fit all three (six stars) in the 7x35s, phi and psi in the 10x50. 

 

IMG_17092021_075744_(1024_x_700_pixel).jpg

 

Once I had Phi Aquarii Hydor) identified I would move on to Neptune, 4.3° away. I would identify the starfields around Neptune and I'd be there.  

 

IMG_17092021_080127_(1024_x_700_pixel).jpg

 

If I were having trouble making that big jump the lambda Aquarii, I would use SkySafari to identify some intermediate stars as guide posts.

 

I would then be familiar with Neptune's location and repeat the process using the scopes finder, probably starting at Phi Aquarii. 

 

Jon


  • Redbetter likes this

#18 rhetfield

rhetfield

    Surveyor 1

  • *****
  • Posts: 1,978
  • Joined: 14 Aug 2019
  • Loc: Suburban Chicago, IL, USA

Posted 17 September 2021 - 10:27 AM

I have experimented with a digital level and a form of an azimuth circle from my light polluted San Diego backyard.  I found to be effective for objects that could be identified as the object in a lower power eyepiece as the object of interest.

 

With objects like Uranus, Neptune or binary stars that require higher magnifications, to identify, I found some star hopping is required to make a positive identification. Personally, it's just easier to star hop from the beginning.

 

From my light polluted backyard, to find Neptune, I would use Safari, I would start out binoculars, either 7x35s with a 9.3° field or 10x50s with a 6.5° field. The 7x35s would probably be best.

 

I would start with Jupiter, it's two fields of view to lambda Aquarii. I would identify phi Aquarii and psi 1,2,and 3 Aquarii. I could fit all three (six stars) in the 7x35s, phi and psi in the 10x50. 

 

attachicon.gifIMG_17092021_075744_(1024_x_700_pixel).jpg

 

Once I had Phi Aquarii Hydor) identified I would move on to Neptune, 4.3° away. I would identify the starfields around Neptune and I'd be there.  

 

attachicon.gifIMG_17092021_080127_(1024_x_700_pixel).jpg

 

If I were having trouble making that big jump the lambda Aquarii, I would use SkySafari to identify some intermediate stars as guide posts.

 

I would then be familiar with Neptune's location and repeat the process using the scopes finder, probably starting at Phi Aquarii. 

 

Jon

How do you do the transition from binos to scope in that scenario?



#19 WheezyGod

WheezyGod

    Explorer 1

  • -----
  • Posts: 89
  • Joined: 07 Jun 2021

Posted 17 September 2021 - 11:28 AM

How do you do the transition from binos to scope in that scenario?


I’m very much of a newbie myself in finding objects.

I sometimes start with my 8x42 binoculars to find either the object I’m looking for or what’s around where I’m starting my star hop. I then look to find the same thing in my RACI which is 8x50 (would help if I also had a Telrad). The FOV in my binoculars is different than my RACI but they’re similar enough to make the transition.

I’ve done this when I’m trying to find 1-2 stars to start my star hopping that I can only see with a little magnification and not the naked eye. If your star hopping are all stars you can see with the naked eye then this method isn’t needed. I also prefer my binoculars not to try to avoid looking at my phone repeatedly when finding something to avoid hurting any dark adaptation I might have. Although sometimes I do use my phone more than I should because I just want to find what I’m looking for.

I’m planning to find Uranus (Neptune I’ll try next year maybe) this weekend with a similar approach using Jupiter and/or Saturn as my starting point like others described. Then figure out where my next stopping point is using binoculars and my RACI, and then hopefully the next stop is Uranus. Will probably fail the first time but it’s worth a shot, and I’ll eventually find it.
  • Jon Isaacs likes this

#20 EricSi

EricSi

    Mariner 2

  • -----
  • Posts: 260
  • Joined: 16 Apr 2021
  • Loc: Seattle, WA

Posted 17 September 2021 - 11:50 AM

Both Uranus and Neptune are plenty bright enough to be easily seen in an 8" Dob. The challenge is in distinguishing them from stars, since their angular size is so small. 

 

Uranus does show a small but very clear disk at around 120X and it has a distinctive pale blue color. Neptune has been a lot harder for me, since its disk is barely bigger than the sharpest focus I can get on a comparably bright star.



#21 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 17 September 2021 - 01:57 PM

Here's a widefield screen capture from Stellarium showing the position of Uranus at the same time and from the same location as the one for Neptune.

Attached Thumbnails

  • Uranus 10-6-21 Wide Stellarium.JPG


#22 Dave Mitsky

Dave Mitsky

    ISS

  • *****
  • Moderators
  • Posts: 99,828
  • Joined: 08 Apr 2002
  • Loc: PA, USA, Planet Earth

Posted 17 September 2021 - 01:59 PM

This is a close-up view.  The star to the immediate right of Uranus is Omicron Arietis.

Attached Thumbnails

  • Uranus 10-6-21 Stellarium.JPG


#23 Henry Decker

Henry Decker

    Lift Off

  • -----
  • topic starter
  • Posts: 24
  • Joined: 27 Jun 2021
  • Loc: Ogden, Utah

Posted 17 September 2021 - 03:35 PM

This is a close-up view.  The star to the immediate right of Uranus is Omicron Arietis.

Thank you for all the effort you have put into your replies, it means a lot.


  • Dave Mitsky likes this

#24 Henry Decker

Henry Decker

    Lift Off

  • -----
  • topic starter
  • Posts: 24
  • Joined: 27 Jun 2021
  • Loc: Ogden, Utah

Posted 17 September 2021 - 03:46 PM

I must admit that I have never used degree circles on any of my Dobs. Every time I contemplate it, I'm daunted by the problem of implementing them and just fall back lazily on star-hopping instead.

So what I'm saying is just a hunch, not from real experience. My guess is that for the average newbie trying to find Uranus -- and much more so for finding Neptune -- degree circles are likely to hurt more than they help. It's a matter of accuracy.

Once you know what Uranus looks like through a telescope, it's pretty easy to identify by its color, which is quite unlike any star's color. But I doubt that a complete newbie would be able to recognize Uranus by its color alone.

To do that you either need to know precisely where within the field of view Uranus lies or else use enough magnification to show it as a disk. Which for a newbie, is probably quite a lot of magnification, maybe even as high as 200X. And placing an object inside the FOV at such high power requires more precision than you can get from any normal setting circles.

 

Neptune has the same issues but worse, since it appears quite a bit smaller than Uranus and much, much fainter.

 

When the original poster said that he "tried to find and view" these planets, I'm curious exactly what he did. One thing I can guarantee -- you definitely won't find either planet just by vaguely sweeping over the right part of the sky. In fact, you can't find much of anything that way. Much worse than the proverbial needle in a haystack.

I used stellarium to get a sense of their general locations in relation to nearby constellations, then when I was outside I would use a planetarium app on my phone (I use skyview) for the exact position, then I used a telrad to get it into the general area and tried to use my 9x50 finder to distinguish colour as other posters had suggested, and I started with a 32mm Plössl to refine it more. I then tested on many stars in the area going up to 160x to try and see if it was any different to the other stars.

 

Since I'm in the Western U.S. there has been a problem with smoke, so perhaps that is contributing to my problem? However those same nights Jupiter and Saturn didn't appear to be affected at all. I also only observe on nights where the smoke is at a very low level or is completely absent so I can't get out as much as I would like to.



#25 Henry Decker

Henry Decker

    Lift Off

  • -----
  • topic starter
  • Posts: 24
  • Joined: 27 Jun 2021
  • Loc: Ogden, Utah

Posted 17 September 2021 - 03:48 PM

Degree circles are your best friend with a dob.  Especially in light polluted skies.  I use sky safari on a tablet to get the coordinates and see what the surrounding star field is like.

 

https://www.cloudyni...degree-circles/

 

My experience is that both planets pretty much look like smaller/dimmer stars and that one almost has to go by color and compare the star field.  I usually don't know for sure until I take the suspected planet out of focus.  If it turns into a blob, it is the planet.  If it shows diffraction rings, it is a star.

 

It generally needs to be over 300x magnification to start looking like a disk.  Even then, it will be small.  Like one of Jupiter's moons small.

I had never thought of that, I'll have to try and bring it out of focus next time I get out!




CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.


Recent Topics





Also tagged with one or more of these keywords: Dob, Planet, Observing



Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics