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BDS316
Carpal Tunnel


Reged: 09/16/09

Loc: Sol 3
Help with Orion doubles please...
      #5581226 - 12/20/12 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


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: BDS316]
      #5581268 - 12/20/12 07:01 PM

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

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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5581688 - 12/20/12 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.


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Help with Orion doubles please... new [Re: BDS316]
      #5581694 - 12/20/12 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.

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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: fred1871]
      #5581894 - 12/21/12 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.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: Asbytec]
      #5582495 - 12/21/12 01:11 PM

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


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: WRAK]
      #5582535 - 12/21/12 01:44 PM

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

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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5583306 - 12/21/12 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


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ziridava
super member


Reged: 08/17/12

Loc: Arad,Romania,Eastern Europe
Re: Help with Orion doubles please... new [Re: BDS316]
      #5584073 - 12/22/12 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://observoergosum.blogspot.ro/#uds-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


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Help with Orion doubles please... new [Re: azure1961p]
      #5584477 - 12/22/12 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.


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: fred1871]
      #5584911 - 12/22/12 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


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: azure1961p]
      #5585004 - 12/23/12 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.

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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5585571 - 12/23/12 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


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: azure1961p]
      #5585692 - 12/23/12 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


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: WRAK]
      #5586099 - 12/23/12 06:29 PM

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

Pete

Edited by azure1961p (12/23/12 06:33 PM)


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Rutilus
Carpal Tunnel


Reged: 12/17/10

Re: Help with Orion doubles please... new [Re: azure1961p]
      #5586666 - 12/24/12 05:26 AM Attachment (19 downloads)

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.


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: Rutilus]
      #5586671 - 12/24/12 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.)

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azure1961p
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5586931 - 12/24/12 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

Edited by azure1961p (12/24/12 10:17 AM)


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5586958 - 12/24/12 10:34 AM Attachment (15 downloads)

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!

Edited by Asbytec (12/24/12 07:51 PM)


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azure1961p
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5587031 - 12/24/12 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

Edited by azure1961p (12/24/12 11:26 AM)


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: azure1961p]
      #5587069 - 12/24/12 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? (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.


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7331Peg
Sirius Observer
*****

Reged: 09/01/08

Loc: North coast of Oregon
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5587227 - 12/24/12 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


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: 7331Peg]
      #5587624 - 12/24/12 06:50 PM

John, thank you. Gotta bookmark that site.

I am sure you will be successful. Staying tuned.


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azure1961p
Postmaster
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Reged: 01/17/09

Loc: USA
Re: Help with Orion doubles please... new [Re: Asbytec]
      #5587681 - 12/24/12 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


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azure1961p
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Reged: 01/17/09

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Re: Help with Orion doubles please... new [Re: azure1961p]
      #5587685 - 12/24/12 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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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: Asbytec]
      #5588156 - 12/25/12 07:22 AM

Quote:

... right on the first ring @ 1.2" arc...



Calculated with 550nm for yellow light the radius of the Airy disk is 0.92" and the first maximum is then 0.92*1.63 = ~1.5" - an error of about 35% compared to the advertised separation of 1.1". But to my experience the bright spot of a companion near the first diffraction ring tends to stick on it so this observation may be valid even if I would not buy it with a 150mm reflector with 28% CO.
Wilfried


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: WRAK]
      #5588173 - 12/25/12 07:54 AM

Wilfred, not sure where you keep getting that figure. Multiplying the Airy disc by 1.63 gives a result 1.22 times too large.

Indeed, if the first minimum is 1.22 lambda/D = .92", then the second maximum is 1.63 lambda/D ~ 1.2".

Rayleigh limit: 1.22 * 550 * 0.206/Dmm = resolution " arc, of course for the Airy disc.

Second maximum a = 1.63 Lambda/D
1.63 * 550 * 0.206 = 184.68/150mm = 1.23" arc


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: Asbytec]
      #5588712 - 12/25/12 05:31 PM

You are right, forgot to divide with the factor of the first minimum: 0.92/1.22*1.63 = ~ 1.23.
Best wishes.
Wilfried


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: WRAK]
      #5588910 - 12/25/12 09:11 PM

Thank you, Wilfred.

I wish you a Merry Christmas.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: Asbytec]
      #5618892 - 01/12/13 11:40 AM

After four weeks of clouds and fog yesterday a few hours of clear sky around midnight. Although it was rather cold near freezing point and Orion was already rather low (about 25 altitude for Rigel) I gave it a try without great expectations as light pollution was as usual rather bad with NEML +2.8mag in the field of view (may be somewhat better at zenit but this does not help very much for observing at lower altitude).
The seeing was rather stable with solid spurious disks and the diffractions rings staying in place even if flickering a bit, but with magnifications above x140 the spurious disks got increasingly fuzzy blobs due to humidity and haze in the air.
Now to 42 Ori: I got clearly no split in terms of dark space between spurious disks and also no 8 but a very pronounced elongation pointing to 6:30 o'clock. As I use an alt/az mount this gives as I checked afterwards for my location and observation time including horizontal flip a position of about 210 corresponding very well with the advertised position. This observation corresponds very well with the image posted by Rutilus with an additional vertical flip (did he use no diagonal?) and a bit lower magnification.
Wilfried


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Asbytec
Guy in a furry hat
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Reged: 08/08/07

Loc: La Union, PI
Re: Help with Orion doubles please... new [Re: WRAK]
      #5618911 - 01/12/13 11:49 AM

I don't know if he used a diagonal, I would think so. I did. His orientation is similar to mine, but I get confused with the flipped and reversed views in various scopes. So, I cannot say, nor whether he was alt az mounted and viewing at a different location in the sky. My scope is EQ mounted.

What scope were you using for elongation? A small refractor?


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: Asbytec]
      #5618976 - 01/12/13 12:23 PM

Sry, forgot: 140mm refractor.
Wilfried


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fred1871
professor emeritus


Reged: 03/22/09

Loc: Australia
Re: Help with Orion doubles please... new [Re: WRAK]
      #5621870 - 01/13/13 10:52 PM

Wilfried has posted a note in the "Some doubles in Tau and a bonus" thread, that gives access to a list he's made of Orion doubles, for testing telescope resolution, pairs bright and faint, even and uneven.

I thought I'd post here my observations of some of these as a way to give easier access (Orion in an Orion thread).

STT 133 in Orion: 0608.0, +2118: mags 7.35, 11.17 (delta-m of ~3.8) separation 3.3" - observed with 140mm refractor, no moon, fairly good seeing, it was surprisingly easy - I could see a hint of the companion at 80x, and it was a clear tiny speck just offset from the primary at 114x. [listed for 150mm aperture]

Also on the list is an old friend, much discussed - part of STF 748, which refers to various of the stars of the Trapezium in the Orion Nebula. The particular pair listed by Wilfried is the AE pairing, mags 6.55 and 11.1, at 4.6" - I've seen this one readily with the 140mm refractor on good nights, not too difficult. [listed for 138mm]

Harder, as often remarked, is the CF pairing, mags 5.06 and 11.5 at virtually the same separation these days, 4.5" (it's been widening) - I've also seen this one, though harder, with the 140mm when seeing cooperates. I don't think CF is in this list.

The 6-inch f/8 Newtonian that I had years ago also showed both C and F.

Next clear night (this week, I'm hoping) I'll try some more from the list along with more of the Taurus doubles.


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WRAK
scholastic sledgehammer


Reged: 02/18/12

Re: Help with Orion doubles please... new [Re: fred1871]
      #5622201 - 01/14/13 07:23 AM

Quote:

... part of STF 748 ... the CF pairing, mags 5.06 and 11.5 ... I don't think CF is in this list...



Fred, this is correct. I restricted the list to doubles with delta-m of less than 6 to avoid it getting too big.
Wilfried


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