Ghost of Jupiter help

[Ursa Major]

Hello,

A few nights ago when it was clearish and the moon was skimming the horizon I gave the ghost of Jupiter a go.

I star hopped from Alphard to Mu Hya and then dropped down to where the Ghost was supposed to be. All the stars were in the right place shown by Stellarium.

Now all I saw was a small blue (I think. it’s hard to tell) star like dot at X26. It looked similar to Uranus at X65 [edit: smiley face] when I looked at it when it was around Jupiter.

I looked on Stellarium and saw the size was 20 arc mins (I think).

I would expect it to be bigger than just a small star.

Now, how much of it would I expect to see in my modest 5 inch scope?

Thank you.

[spaceboy]

It's as if you was looking at Jupiter but with out the cloud bands or moons. Use the same magnifications you would use if looking at Jupiter and find what you would consider to be the same size as when looking at Jupiter. It is a nebula so there will be the usual hindrances from full moons and LP.

SPACEBOY

[Ursa Major]

Thanks Spaceboy,

I went out tonight with my higher mag eyepieces and BOOM, there it was.

I don’t know why stellarium says it is 20 arc mins when Jupiter is 33 arc secs and they look pretty much the same size. I even thought it looked a bit smaller than Jupiter.

Am I just seeing the inner section of the nebular or am I being stupid reading the apparent size wrong.

Anyway, it was a lovely sight.

[Nexus 6]

I think the size is correct Ursa Major

well done in seeing it, did you observe any colour?

nice link on it here

Observing at Skyhound: The Ghost of Jupiter

[Ursa Major]

I’m really not sure if I saw colour. It was very dim its difficult to tell. I might have seen a slight greeny blue when looking at it at low power where the colour was more concentrated and easier to pick up? The weather wasn’t that good yesterday, a bit hazy, so I’ll give it another look when the conditions are better and maybe I’ll see colour then.

[spaceboy]

Glad to hear you added another DSO to your list. You may find GOJ looks totally different under dark skies as dose most thinks so it's always best to keep an open mind regards dimensions etc. M31 for example looks huge under dark skies compared to LP skies.

[acey]

I looked on Stellarium and saw the size was 20 arc mins (I think).

I would expect it to be bigger than just a small star.

Now, how much of it would I expect to see in my modest 5 inch scope?

20 arc minutes (a third of a degree) can't be right - more likely 20 arcseconds (180th of a degree), comparable to the apparent size of Jupiter. At a magnification x26 its image in the scope would subtend about 0.14 degrees, which is like a 1mm disc held about 40cm from the eye.

Well done on seeing it, and try using higher power to get a better view.

[Ursa Major]

20 arc minutes (a third of a degree) can't be right - more likely 20 arcseconds (180th of a degree), comparable to the apparent size of Jupiter.

Have you taken a look at stellarium? Am I reading it wrong or have stellarium got it wrong?

I have bumped the power up to x130 since seeing for the first time and it does take on a rather ghostly appearance.

[Demonperformer]

Burnham quotes the size as 40"x35", with the "bright strongly elliptical inner ring" being 26"x16", so maybe that is what stellarium is thinking about.

[acey]

Have you taken a look at stellarium? Am I reading it wrong or have stellarium got it wrong?

I have bumped the power up to x130 since seeing for the first time and it does take on a rather ghostly appearance.

I've never used Stellarium but ' is arcminutes and " is arcseconds, and according to the NGC the Ghost of Jupiter has size 45" x 36". So at x26 it would have been more like a 2mm disc held 40 cm away.

To get the data, type "NGC 3242" into the form on this page:

NGC/IC Project Public Database

[Ursa Major]

OK, thank you DP and acey,

It seems like there is just a lot of variation in the sizes quoted by different programs.

That looks like a very useful website for objects that there aren’t pictures of in stellarium.

Thanks