Gamma Virginis Split ....... ???

[John]

Tonights seeing was superb tonight - I knew that as soon as I turned my 8 inch dob on Saturn - the best views that I've had this year. I then tried Gamma Leonis and it was split wide and easily at 100x and upwards and I noticed faint diffraction rings around the componants - in fact the star images looked very refractor-like which confirmed my assessment of the seeing and my scopes collimation.

So I thought I'd have a shot at splitting Gamma Virginis - I knew that it was a very close double at the moment but I did not look up the exact separation before observing. Rather to my suprise, at 300x (using my 4mm TS Planetary HR eyepiece) I could see 2 distinct componants of more or less equal brightness and very nearly, but not quite touching - the separation was the faintest of dark lines and came and went as the seeing varied but it was distinct. Experimenting with different powers I found I could just about separate the stars at 250x as well (Nagler 4.8mm).

Having come inside now and checked the current separation of Gamma Virginis I'm amazed to find it listed at around .5 sec of an arc. The night was good and the scope is in great collimation but I would not expect to be able to achieve a .5 sec of an arc split, even on the best of nights.

Has anyone else with a similar aperture scope been able to split this double as well ? - or am I kidding myself

It certainly looked like 2 very, very close, but separated stars to me.

I'd be interested in other folks experience of this double.

John

[barkis]

It is going to be a case of believing your own eyes John. You get the perfect seeing, no dancing images.

Your scope is in excellent collimation. The double is about as close as it gets, at about .4 arc secs.

At 300 x depending on the FOV, it is going to be moving pretty quickly.

The resolving power of your scope will be about .56 arc secs. The two components, each at mag. 3.6

I know it sometimes auto suggestive, and one may see what one wants to see, but you don't strike me as a person who say what you thought you saw. You only expressed doubt after you established the separation. Had you looked before starting the observation, would you have even bothered to try.

I think under the conditions you were working in, you probably did split them. What you have to do now, is do it again.

Ron.

[lunator]

John

Based on the 6th orbit the pair were 0.997" at the start of 2008.

This would put them at about 1" now well within your scopes capabilities.

Cheers

Ian

[John]

John

Based on the 6th orbit the pair were 0.997" at the start of 2008.

This would put them at about 1" now well within your scopes capabilities.

Cheers

Ian

Thanks Ian - that's re-assuring. I'm still very pleased to have achieved that - it's the closest double that I have been able to split so far and proves that my scopes performing well :-)

John

[lunator]

John

If you get a chance have a go at zeta cancri. It's a triple withthe 2 closest components very similar to Porrima

Cheers

Ian

[lunator]

John

Had a go at 3 double tonight.

Zeta Cancri easy split A-C pair at x50. At x200 the AB pair was elongated but not split. This is due to the heat haze off the houses in the next road.

Porrima Split at x300 & x240. The 240 view was more pleasant to view. The conditions meant the clear split came and went.

Xi Uma easily split at x240 and remained separated at all times.

Cheers

Ian