Can you see Neptune with a Dobson XT6?

[thalatta]

Hello, does anyone know if you can see Neptune with an Orion XT6 Dobson (150mm aperture, 1200 focal length, f/8)?  I have a few eyepieces: Explore Scientific 5.5mm, Orion Expanse 9mm, and a 25mm Orion Sirius Plossl, and a Barlow 2x.  And also, when is a good time to see Neptune ?  Thanks! Shane

Edited June 15, 2020 by thalatta

[kerrylewis]

I would say yes. I can see it with my 100mm refractor.

It is not particularly conveniently placed at the moment but is visible in the early hours. It happens to be very close to Mars at the moment. The main difficulty is identifying it rather than any surrounding stars. Using high magnification will,usually show its disc and it is also a distinctive blue colour. 

Do you have any planetarium software? This would show its location. 

[Waddensky]

Neptune is visible even with binoculars. Currently, the planet is a late night object in the constellation of Aquarius, close to Mars. In September, the planet is in opposition and visible all night.

Edited June 15, 2020 by Waddensky

[Kyle Allen]

Neptune is around magnitude 8 so your 6 inch Dobsonian will easily show it - it can even be seen in binoculars. Currently, it is very close to Mars so visible in the early hours of the morning. The difficulty will be in identifying it because it is hard to tell apart from other stars at low power. High power will reveal a bluish disk. 

I have attached some screenshots from SkySafari. As you can see, it is to the West of Mars. It makes a triangle with a magnitude 6 star to its East and a magnitude 7 star to the South. The circle shows a 1.7 degree field of view. You won’t see Nereid as it is magnitude 20! 😀

[John]

Yes. I've seen it with my 6x30mm finder scope.

It is a very small disk though - even at 200x you will only see it as a tiny blue/green spot. Clearly not a star though, when observed at those magnifications.

I have even managed to see Neptune's brightest moon, Triton with a scope. Generally it needs my 12 inch dobsonian but I have managed to spot this faint little point of light with my 130mm refractor as well. Lots and lots of magnification needed for that challenge !

 

 

[Paul M]

Neptune is surprisingly easy to see, if you know where to look! I often look it up with my 10 x 50's.  Best done with a finder chart specific to you observing date or one of the better planetarium programs. Stellarium on Windows or SkySafari on mobile devices. I memorise an asterism or starfield that will guide me to Neptune early in the season but once it's spotted I can find it much more easily thereafter. 

As John says above, the disk is discernible in small instruments with good seeing and adequate magnification. It's always nice to spot the furthest known planet in the solar system with any kind of instrument (poor old Pluto!).