Sigma Orionis

[chiltonstar]

Had another look last night at sigma Orionis (after many years!) - a recommendation from Moonshane in another thread. Used my 5" Mak at x100 and x190.

Spectacular, 4 close components with Struve 761 nearby adding 3 more. The C component of sig Ori was a bit of a struggle though, however once Orion was a bit higher in the sky it popped out quite nicely as a white pinpoint beside the white primary (A/B). As expected, my perception of the colours of the components was a bit different from the books though - I would have said that D was purpleish and E more blue. Other impressions of the perceived colours of this multiple star would be interesting?

Chris

[Marki]

Sweet. Will look out for this tonight if it clears!

[John]

Sigma is a lovely grouping

Orion has some nice binaries notably, Sigma, Theta Orionis (the famous Trapezium) with it's 4 bright components plus the E & F stars, Rigel with it's 9th mag companion and the challenging Eta Orionis with a separation of around 1.7 arc seconds.

Plenty more too for the keen binary fan

Simply one of the best constellations for the amateur astronomer !

[cotterless45]

I always try and show folk Sigma Ori. It's easy to find and responds well to higher magnification, neat,

Nick.

[lunator]

It is fantastic object Always have a look this time of year

Cheers

Ian

[Moonshane]

I'll report back what I see next time the sky is visible - maybe next Feb?

[John]

I'll report back what I see next time the sky is visible - maybe next Feb?

:grin:

[chiltonstar]

Sigma is a lovely grouping

Orion has some nice binaries notably, Sigma, Theta Orionis (the famous Trapezium) with it's 4 bright components plus the E & F stars, Rigel with it's 9th mag companion and the challenging Eta Orionis with a separation of around 1.7 arc seconds.

Plenty more too for the keen binary fan

Simply one of the best constellations for the amateur astronomer !

Certainly is!! I had a clear night last night for the first time in a couple of weeks, so I had a look at a few of these with my 5" Mak (I've looked in the past with my 4" achro frac, but not with the Mak.

Rigel - very easy and clear (good in the ED80 as well) nice.

Eta Orionis - hard at first (Mak), then gradually settled as the scope cooled into two disks nearly touching each other, yellowish/blue (ED80 didn't quite resolve, showed as an ellipse with coloured ends).

Theta Orionis - the four easy of course, could just about see the E component, but not the F; I'll try again when Orion is higher.

Chris

[John]

Good going Chris

I've found I need 120mm of aperture to routinely see E & F in Theta. My 102mm ED has done it a couple of times under excellent conditions but usually it's just E that shows.

Eta is a great pair and can be quite a challenge - I can just split it with my 102mm under good conditions.

I often use Sigma and Rigel as a test of seeing before moving on the the fainter components of Theta. If Rigel is a struggle then things are bad !

[chiltonstar]

I had another try at Eta Orionis two nights ago (good seeing - GRS was great too earlier in the evening) and got a very clean separation - best yet....Encouraged me to try 32 Orionis (also a good separation, even at 1.2") and 52 Orionis (1.1", two clear disks side by side, but no space between them or "black line"). As ever, I am surprised at how good the resolution can be with a 5" Mak when the seeing is good and the scope is really cooled down.

Chris

[Mark at Beaufort]

Well done on the doubles Chris an enjoyable thread to read. Good information for members wanting to find a good selection of doubles.

It shows how good these Mak Cass scopes are for double stars.

Mark

[kirkster501]

Loads of multiple star systems in Orion and Sigma Orionis surely one of the best. Some very tight binaries there that can test you optics and seeing very well.

[Marki]

Had some good fun with these tonight. Maybe seeing is particularly good tonight? 100mm f13 x185 split sigma nicely (inc the c component), and easy on the struve 761 triple. Altogether a marvellous grouping.

Cracked Rigel for the first time tonight. Maybe with Orion being a little higher, that helped. Spent about 10mins peering into the purple glare around Rigel, and then the tiny speck of the companion suddenly popped into view, plain as anything. Weird how that happens sometimes.

[Moonshane]

Indeed Mark. I think that we all probably blame our eyes, our optics, our eyepieces, our collimation but when it comes down to it, declination and seeing have more effect than anything I reckon when it comes to splitting doubles and of course planetary detail. I suspect also that once you have split a double or seen a feature/faint object it becomes more obvious in future as you 'learn' to see it. that's how it works for me anyhow.

[chiltonstar]

Indeed Mark. I think that we all probably blame our eyes, our optics, our eyepieces, our collimation but when it comes down to it, declination and seeing have more effect than anything I reckon when it comes to splitting doubles and of course planetary detail. I suspect also that once you have split a double or seen a feature/faint object it becomes more obvious in future as you 'learn' to see it. that's how it works for me anyhow.

Absolutely - you have to "learn" to see some objects.

I can't wait for Sirius to be high enough to make it worthwhile to look for the "Pup". I've seen it once with an observatory scope, but never from home.

Chris

[Ags]

Why have I never looked at Sigma Orionis? It sounds wonderful.

[Marki]

Absolutely - you have to "learn" to see some objects.

I can't wait for Sirius to be high enough to make it worthwhile to look for the "Pup". I've seen it once with an observatory scope, but never from home.

Chris

Now that sounds like a challenge! Trouble is Sirius is only just making it above the trees on my south/southeastern horizon by midnight...might have to wait a month or so to stand any chance... .

Think I might try some of the other Orion doubles in the interim. ANyone managed 42 Orionis? I thought I managed it last night, but I think I was actually looking at Iota - doh!

[cotterless45]

Hi, this might help;

http://www.carbonar.es/s33/Orion/42_orionis.html

Will put it on the list !Nic

k.

[Moonshane]

well my Chrissie pressie is the Cambridge Double star atlas. it, erm, fell open before I gave it my wife and looks superb. in fact, it will be my recommended star atlas for everything I think from now on. looking forward to more doubles soon.

[chiltonstar]

well my Chrissie pressie is the Cambridge Double star atlas. it, erm, fell open before I gave it my wife and looks superb. in fact, it will be my recommended star atlas for everything I think from now on. looking forward to more doubles soon.

I find it a superb guide with excellent maps that I very often use for non-double observations. It fascinates my 18 month old grandson who runs his fingers up and down the spiral bind and points at any star in the maps and says "dah" (I haven't managed a translation yet). The separation figures given are not always completely up-to-date of course....

Chris

[chiltonstar]

Think I might try some of the other Orion doubles in the interim. ANyone managed 42 Orionis? I thought I managed it last night, but I think I was actually looking at Iota - doh!

Had a try for 42 Ori tonight and managed 45 mins before the blood froze. I can just see there are two stars there , with the minor one in the correct position, but would need more mag than the x190 I was using to see it better, which is probably beyond the limits of my 5" Mak.

Chris

[cotterless45]

We had a go with a Bresser 120, but at minus 6 the ice was problematic.

Kappa Geminorum was good though aswell as the usual suspects in Cassiopeia,

Nick.

[Marki]

I tried for c.20 mins and failed at x140, then x160, x187 and at then at x225 (pure desperation!) - wasn't convinced (with my 125mm achro). I think there was too much moisture freezing out of the air, and the seeing wasn't so good. Orion wasn't too high either - could make out the four main stars in the trapezium, but no hint of e and f. Managed sigma nicely though. I gave up after midnight (around 12.30). Impressed you lasted to - 6 Nick, my scope was coated with frost by the time I gave up at around -2 .

[chiltonstar]

Last night was crystal clear here with excellent seeing, and although -6, the air was dry so no dewing or frosting up.

Finally, 42 Ori yielded to the Mak at x250 - two fine disks touching each other. I tried x390 as well (which is way above the x50 per inch of aperture rule), which showed the two components clearly although they were slightly blurry. Had a look at Vesta (I'd never seen it before) as a bonus.

Chris

[Marki]

Nice work Chris!