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Help with Orion doubles please...

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#1 BDS316

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Posted 20 December 2012 - 06:27 PM

One of my goals for this season is to split all the Orion doubles listed in the new edition of "Turn Left at Orion."

So far, no problem with the easier ones like Mintaka, sigma, Eta, Rigel,sigma (nice!!) and Meissa. In the trap we saw A through E but not F, but the seeing conditions were suspect because F was not visible in a friend's 8 inch flourite apo either.

I would like to split 52, 32 and 42 which are all in the neighborhood of 1.1-1.2 arc seconds with my 8 inch Dob. What kind of magnification are we talking about, and any suggestions for F other than waiting for better seeing?

Thanks

#2 Asbytec

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Posted 20 December 2012 - 07:01 PM

I Split them cleanly at 300x, but I think you can begin to see a split just over 200x.

#3 fred1871

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Posted 20 December 2012 - 11:34 PM

Norme, which double or doubles are you referring to with your reply? - reason is that they're not all equal in ease or difficulty. In particular, 42 Ori is going to be very tough because of near 3 magnitudes difference between the components at only 1.1" separation.

In a thread on 32 Ori you mentioned seeing 32 and 52 with 300x. With 52 Ori the components are equal, making it not too hard; with 32 Ori, there's a difference of 1.3 magnitudes, so it's tougher; but it's not in the same league as 42 Ori in terms of brightness difference. And current measures in the WDS list 32 Ori at 1.3", a fraction wider than 42 Ori at 1.1".

I last checked 32 Ori two years ago - 200x on the 140mm refractor just split the thing.

So, have you seen 42 Ori separated with the 6-inch? It would be an achievement given the brightness difference and closeness, and a secondary mirror brightening the diffraction rings. Well done if you have. I haven't tried 42 Ori yet - I'm waiting for a (rare) steady-seeing night.

42 Ori visible with an 8-inch Dob? - unlikely if it's a basic quality f/4.5 version, and if it hasn't cooled fully.

#4 fred1871

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Posted 20 December 2012 - 11:38 PM

F in the trapezium is a tough one, unless the seeing really co-operates. I've seen it with 5.5-inch refractor and 6-inch f/8 Newtonian, but each time the seeing was pretty steady. Some folk have seen it with smaller scopes than those I used; so it's certainly within reach of an 8-inch.

#5 Asbytec

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Posted 21 December 2012 - 05:07 AM

Fred, I have not seen 42 Ori, might like to try it, though. I was primarily discussing 52 and 32. On 42 Ori, I knew nothing about their magnitude separation, only the separation he mentioned.

Agree on F, wait for a calm night.

#6 WRAK

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Posted 21 December 2012 - 01:11 PM

Sissy Haas is also waiting for observation reports of 42 Ori.
Wilfried

#7 Asbytec

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Posted 21 December 2012 - 01:44 PM

Will put it on the list for tomorrow. Thanks, Wilfred, might give me something to do after Jupiter.

#8 azure1961p

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Posted 21 December 2012 - 10:30 PM

A more difficult pair I split than 42 0rionis was 2es Vulpeculae . I failed quite a few times even in good seeing with the 8". Then on a GREAT night 9-10/10 it resolved at 433x . It was this barest glimmer of a shadow of a star - a ghostlike thing even but a certain point. Sep was 1.8" and mags were 5.5v and 9.3v. Even a little lees than great seeing smeared it out of existence. Having done that with my 8", if his is at least good optically it ought to be doable but at about. 50x per inch and some truly good to excellent seeing. Can Norme make it with his 6"? I would be tempted to say no but all his Jupiter observations so far beat mine! Under 9/10 Od be curious to hear his results.


Anyway nothing but the best seeing your likely to get and about as much mag as your scope can put out. On doubles some folks profitably exceed 50x per inch but you've gotta have the optics to pull it off. You just may too.


Pete

#9 ziridava

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Posted 22 December 2012 - 01:11 PM

Brian
Speaking strictly about 52 Ori,the lowest magnification I used to successfully split this fine double star was 116x/old 7.5mm Celestron Plossl on my 125mm F/7 Dobsonian.
This happen last Spring on a night with decent to good seeing.
I think you are right about stars E and F in Trapezium,to see them one need good seeing.But definitely they are within the reach of an 8 inch Newtonian.I saw them in my 8 inch F/6 Dobsonian at 200x/ Tele Vue Radian 6mm.
A picture of this Ravneberg style Dobsonian named ,,Toleascope'' -after the friend who gave it to me-may be seen on my blog,in the right column:

http://observoergosu...-search-results

32 Ori is a very recent aquintance to me.
I don't know nothing about 42 Ori...but I'm listening.
I wish you good luck,and you will certainly have,Orion is a gold mine!
Mircea

#10 fred1871

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Posted 22 December 2012 - 06:22 PM

Pete, your comments on 2 Vulpeculae got me looking at my own notes. Sure enough, a very tough double - I got to see the companion as a "glimpse star" flickering in and out of visibility with a C9.25 at 300x, on a pretty good night.

I've now checked the WDS and the current photometry - probably Tycho - gives a brighter magnitude for the secondary star. The listing is now for mags 5.43 and 8.75, so delta-m is 3.32, not 3.8. Therefore I'd say that 42 Ori will definitely be tougher than 2 Vul, as the delta-m on 42 Ori is not much less at 2.9, and the separation much tighter - 1.1", vs 1.7" for 2 Vul.

I'm now less optimistic about splitting 42 Ori. :(

#11 azure1961p

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Posted 22 December 2012 - 11:58 PM

Then that's one tough double to split. From what Zive experienced with 2ES, I wouldn't even attempt 42 unless the stars were darned near still and that's a lot to ask of a winter sky in Connecticut.

Thanks for your input Fred. They SCT sounds first rate.

Pete

#12 Asbytec

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Posted 23 December 2012 - 01:35 AM

You guys are really tempting me to observe 42 Ori. How hard can it be? :) First clear night, Christmas or not, it's on the list.

#13 azure1961p

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Posted 23 December 2012 - 12:58 PM

Well in CT it'd be difficult unless the diffraction pattern stayed still. You get great seeing u might pull it off. If its like ES though its a mere ghost of a speck, tiny and fleeting.

Give it a shot.

Pete

#14 WRAK

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Posted 23 December 2012 - 02:13 PM

The present state of my RoT model indicates a 50% chance for a split with a 170mm refractor, for a reflector you will have to add your CO percentage to this value. Looking forward to your reports.
Orion comes into my field of view in January and I hope too for a clear night to try it myself even if I do see a zero chance with my 140mm refractor.
Wilfried

#15 azure1961p

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Posted 23 December 2012 - 06:29 PM

With seeing obliging perhaps. You can't beat the locale though!

Pete

#16 Rutilus

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Posted 24 December 2012 - 05:26 AM

I've been reading this thread with great interest as I've never observed 42 Ori before.
Last night I had a go with 140mm f/8.5 Achromat refractor.
I went into the observation blind as I don't have a position angle measurement for this star.
At 342 - 400x power I could see a faint speck of light at around the following position angle of 195 - 200 degrees.
Seeing conditions were not the best and the small speck of light would come and go.

Here is a drawing (not to scale) Anyone know the current P.A. for this star. If the speck of light is near too the
current P.A. then I think the companion is certainly doable in better seeing conditions, at least with my 140mm refractor.

Attached Files



#17 Asbytec

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Posted 24 December 2012 - 05:38 AM

Rut, that's an amazing observation. I am going for it tonight. Nice to know what to expect. Looks pretty challenging. No idea of the PA or Sep or the magnitude of the companion. (Not yet, anyway, I like going in blind, too.)

#18 azure1961p

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Posted 24 December 2012 - 10:16 AM

Rut that's a terrific observation testament to scope and observer . I was in the region last night and wanted to give it a whirl but the seeing was poor like 4 on Pickering. Got a lot of decent 91x doubles though!!

Great catch and illustrations.

Pete

#19 Asbytec

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Posted 24 December 2012 - 10:34 AM

Okay, "how hard can it be?" Do I have anything on my face after eating those words? That was THE most difficult double star observation I've had the pleasure to undertake.

Seeing was about 7/10, transparency 4/5, maybe, gibbous moon not far. The trap, well, E was readily seen, F only maybe twice.

So, if this is correct, then I split 42 Ori. If not, then I failed. But, I am reasonably sure I was able to detect a companion, not as a distinct spurious disc, but as a brightening of the first ring near PA 190. There were some moments where it looked like a much more difficult version of 32 Ori. (Sketch coming to be added below.) No nebulousness noted.

Well, I located 42 Ori at 109x and could not see any indication of a double star. Jumping to 174x, no indication. So, jumping to 380x still showed no immediate signs of being a binary pair but did seem a nice blue color (compared to 45 Ori which was more yellow.) If you didn't know this was a binary star, you'd probably never see it under these relatively average conditions - not according to my experience tonight. So, I decided to drop back down to 320x (6mm TMB II @ f/13) to get the best chance given the seeing.

Observing for many minutes, I did get some indications of a bright knot forming on or very near the first ring at about PA 190. Of course the rings were not entirely steady, blurred fairly often, but showed arcs most of the time and were calm only infrequently.

So, while the rings did dance a bit, it seemed there was a more consistent bulge at PA 190. There were a few moments when I was very sure the companion was there. You know, sometimes when you work and wait to see something and you silently whisper, "yea" when you see it. I had a few of those moments. So, I backed down to 260x (OU 12mm HD Ortho and 1.6x Barlow.) I got that same observation a few more times during the observation.

So, I decided to try again at 380x (8mm TMB II and 1.6x Barlow.) Again, pretty much the same result with the bulge at PA 190. However, at this magnification I did see that same effect once or twice at about PA 330. I suspect, however, my collimation might have been even so slightly off in that direction, so I am not sure about this sighting at PA 330.

Okay, so a difficult, very difficult observation over the course of an hour. If I have to call it, and I am reasonably certain I can, then the companion is PA 190 (+/-) and right on the first ring @ 1.2" arc. Man, I would love to be right and to have split it. It certainly seems consistent with Rutilus' observation. That's great!

Attached Files



#20 azure1961p

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Posted 24 December 2012 - 11:19 AM

Sorry Norme you didn't see it. The true PA is 207 and the bureau of double star Postion Angle Detection and Inference dictates that a PA angle deemed in excess of 5 degrees is cause for observational dismissal of recognition and furthermore requires a hand written note of apology to Bertha Gutbridges the secretary of this 300 year old fraternity .

Seriously though Im glad you got it. The impression sounds like my 2ES experience and while it was outside of the rings it was utterly spirit like!!! Congrats for an ob that'll stand appreciated for time to come!
It's a great region actually - I did the 70x-91x thing when I saw the seeing was *BLEEP* and it was fun but I wish I could've seen it. Nice drawing love the color - the elongation of the star on the ring. This is an effect of diffraction huh?

Pete

#21 Asbytec

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Posted 24 December 2012 - 11:41 AM

I was just firing off a letter of apology when I decided to visit them in person, tip my hat, and tell them to eat my shorts. :) Thanks for the chuckle, Pete.

What is the magnitude of the companion? And where did you get the actual PA? Dare I ask from where you pulled it? :lol: (Serious, do you know where to find it?)

Man, that was a tough one, Pete. Maybe that one shows what everyone means by diffraction and unequal pairs being difficult. Rutilus looks to have had a better view of it, probably less diffraction helped. And he seems to have noted a little nebulousness. I wonder if that played a role even though I really didn't notice any.

Thank you, Pete, your turn will come. That was a challenge.

#22 7331Peg

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Posted 24 December 2012 - 01:18 PM

The WDS is still the best place to get the most current double star data.
I usually use the interface to it provided by the StelleDoppie site, which shows this data for 42 ORI.

The most recent observation for this one is 1995. There's no orbital data for it, and it shows very little proper motion, so there's no reason to expect any noticeable change in the PA and separation. I also noticed that the eagle-eyed Reverend Dawes is credited with discovering 42 ORI as a double in 1848.

Nice work, though -- looks like both Norm and WRAK got it. From the looks of those sketches, it looks very similar to Delta Cygni in a 60mm refractor, and every bit as difficult. Would love to give it a try with my six inch f/10 if the weather would just cooperate for a night.


John :refractor:

#23 Asbytec

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Posted 24 December 2012 - 06:50 PM

John, thank you. Gotta bookmark that site.

I am sure you will be successful. Staying tuned.

#24 azure1961p

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Posted 24 December 2012 - 07:39 PM

Of think Delta Cyg is easier - I'm still using 2ES as the near equivalent and even when Delta was closer it was still baggeble with the 8 in 6/10 seeing.

Pete

#25 azure1961p

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Posted 24 December 2012 - 07:42 PM

Oh I got it from Sky Safari on my iPod. As mentioned though the Stella Dolppe site that accesses the WDS is still the best site tho this app is really flat out amazing really.

Pete






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