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Porrima split with my 4" Vixen


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I had a nice session with my Vixen 102mm ED refractor in the early hours this morning which included Porrima (Gamma Virginis).

I used 6mm (110x) and 4mm (166x) UO orthos and then a barlowed 6mm Ethos (3.75mm - 177x). With the 6mm ortho I saw a well defined "peanut" shape with the 2 stars appearing to touch but a thin line of darkness between them coming and going with the seeing. At the higher power the split between the componants was clear and stable for decently long viewing periods - a definate split in my book :)

I believe the separation is widening and around 1.6 arc seconds currently. I'm pleased with the 4" being able to split this under my observing conditions. I recall that I needed a 5" refractor to do this last year. ;)

Edited by John
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I believe the separation is widening and around 1.6 arc seconds currently.

Yes, the ephemeris has seperation 1.59 arc sec for 2011.0 and 1.78 arc sec for 2012.0. A few years ago this star was difficult or impossible with 12" but is now well within the range of modest scopes, obviously with the benefit of reasonably steady seeing.

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Yes, the ephemeris has seperation 1.59 arc sec for 2011.0 and 1.78 arc sec for 2012.0. A few years ago this star was difficult or impossible with 12" but is now well within the range of modest scopes, obviously with the benefit of reasonably steady seeing.

Thanks Brian :)

I've been observing this one on and off for 30+ years now so I have a "soft spot" for it. I recall I needed an 8" 3 years back.

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Hi John

It has been fascinating to watch it close up and re-open.

At Lucksall you should get a decent split :)

I hope we get some decent skies there - I'm planning on taking my Intes 6" mak-newt which is great on doubles (and much else as well) :p

Perhaps we should arrange for a couple of artifical stars to be positioned close together a mile or so away from the site in case of clouds :glasses1:

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I hope we get some decent skies there - I'm planning on taking my Intes 6" mak-newt which is great on doubles (and much else as well) :)

Perhaps we should arrange for a couple of artifical stars to be positioned close together a mile or so away from the site in case of clouds :glasses1:

Sounds like a plan :p;)

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  • 1 month later...

I find this a very fascination double as you can actually follow it from easy split-difficoult-impossible and back again to splitable.Very intressting to observe a star in motion.

I have "figured 8" this one last year with my C80ED at 205X.

In my OOUK 8" f/6 it is a beutiful split at 320X

/Magnus 57*N.

Sweden

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  • 5 weeks later...

Hello all.

While observing Saturn last night I couldn't resist a quick go at Porrima as it is currently so close to the planet. At 100x I got the peanut & 200x split the pair but it wasn't that well defined. No wonder at less than 2 arc secs!! I thought it was over 3. Quite pleased now!

Edited by Doley68
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I had a try tonight with my Mak 127mm (x185) as the seeing was reasonably good. Looks like a pair of headlights seen through a dancing disk of fuzz as the seeing comes and goes, but no clear split between the two (there shouldn't be theoretically with a 127mm scope at the current separation I suppose).

Chris

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I had a try tonight with my Mak 127mm (x185) as the seeing was reasonably good. Looks like a pair of headlights seen through a dancing disk of fuzz as the seeing comes and goes, but no clear split between the two (there shouldn't be theoretically with a 127mm scope at the current separation I suppose).

Chris

I think you would do it under good seeing conditions Chris - the 127mm maks are good scopes for binary stars :D

Tight pairs are a real test of seeing conditions as well as scope and observer - that's why I find them quite addictive :)

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I was assuming (maybe wrongly) that as the theoretical halfbandwidth resolution of a 5" is about 1 arcsec and the separation of Porrima about 1.7 arcsec at the mo, I would get at best, a peak-to-valley effect where the peak was higher than the valley, but there was no clear baseline between them. Experts?

Chris

PS Yes, the 127Mak is stunning for doubles, far better than my 4" refractor.

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  • 4 weeks later...

I have finally got around to nudging the scope slightly away from Saturn and have just had a look at Porrima. Relatively straight forward in average seeing (although it's in an out a bit) at 200x with the 6" f11. On a good steady night this should be doable in most average scopes at around 200x I think?

Great to see such a previously tight / impossible double opening in a few years let alone our lifetimes! Thanks for the original heads up John.

The flocking definitely seems to have improved matters a bit with less scatter apparent (although there was never a lot) and a very black sky with excellent contrast. Glad I did it.

Edited by Moonshane
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I've been looking at Porrima, Iota Leonis and other multiple stars with my newly acquired Celestron C5 SCT tonight. I've been tweaking the collimation and I seem to have got it more or less spot on now. Both the above plus a number of other binaries nicely split - Iota Leonis did need 250x to show it at it's best. These coupled with splendid views of Saturn have already created a strong admiration for the capabilities of this compact scope :)

Edited by John
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