Neptune and nearby faint star

[David_W]

Hi Everyone,
I had a look at Neptune on Saturday night, as I had some pretty good stable conditions (a rarity these days). Using 280X I could see a very faint star near the planet to it's ~east, several planet diameters away.

I don't expect to see Triton with my 5" refractor of course, but I was wondering what the magnitude of this star was. I suspect around 12th, as 47 Tuc was well resolved that night and it has it's AGB stars at around that magnitude.

Does anyone know any links that can tell me? It'd be great to know what kind of magnitude I can get down to from my rural back garden.

Cheers,
Dave

[steve000]

Hey Mate,

stellarium with the star catalog downloaded could show you. It has helped many times in the past finding obscure objects

[mithrandir]

Stellarium doesn't label all stars. CdC usually gives more info.

Given Neptune at:

Coordinates: Apparent 2000.0 Topocentric
RA: 22h09m35.68s DE:-11?56'25.6"
Apparent RA: 22h10m12.74s DE:-11?53'00.0"
Mean of the date RA: 22h10m10.49s DE:-11?53'13.4"
Mean J2000 RA: 22h09m33.44s DE:-11?56'38.9"

My guess from the UCAC3 catalog at a distance of 14'15" and PA 88 is:
Star
3UC 157-290716
Visual magnitude: 12.79
Colour index: 0.72
Proper motion in right ascension: 0.005
Proper motion in declination: -0.008

Coordinates: Apparent 2000.0
RA: 22h10m33.883s DE:-11?55'54.12"
Apparent RA: 22h11m10.935s DE:-11?52'28.13"
Mean of the date RA: 22h11m08.689s DE:-11?52'41.54"
Astrometric J2000 RA: 22h10m31.647s DE:-11?56'07.45"

Andrew

[mental4astro]

A google search of Triton's visual magnitude has it around 13.6 to help out a bit. The visual limit magnitude of a 5" scope is around 14.2. You may just be able to spot Triton after all if conditions are especially good.

[David_W]

Thanks for the replies Guys, I'll be taking another look at Neptune on the next clear and steady night, so will check the position of that star again. You never know, it might have been Triton, the sky was superb that night.

Cheers,
Dave