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Seeing Orion Trapezium stars E&F - tips


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I managed to just see Theta Orionis E on Friday evening from a local dark site (Bortle 5) with my 250PX at around 150x magnification. Anything higher or lower and it just disappeared. I tried again last night from home (Bortle 6) but with no joy. The scope is certainly capable of seeing both but dark(er) skies and good seeing are neccesary.

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You'll have no problems nailing it with your 10" dob, I've seen it regularily enough and from typical surburban light polluted skies, the hardest aspect I find is having the seeing steady enough as the F star has a habit of blurring with others if the image jumps up and down quite a bit. Go relatively high powered (ie 9mm) and you'll have this 'in the bag'.

I found this site quite useful:

http://www.laughton.com/paul/rfo/trap/trap.html

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  • 3 years later...

Sorry to dig this thread up from the past, but I wanted to update my comments on this given recent experiences.

I've now convinced myself that, assuming well cooled and collimated optics of a good standard, seeing conditions are by far the most important factor in being able to see the E & F stars, over and above aperture.

I previously posted that I struggled to get F in my 8" mak. With experience since then, I would say this was largely due to my inability to cool and collimate it correctly, plus the local seeing conditions. I was just never getting tight enough star images.

Recent experience with my Tak FC-100D, a high quality 4" Fluorite doublet have shown that, if seeing conditions are good then E and F are actually relatively easy in this scope at around x130. During the last week, the Jetstream has moved south after being over the UK for quite some time, and I've been having the most wonderful views of Jupiter, showing incredible detail and above all being very steady in the eyepiece. At the same time, E & F have been regular viewings for me, E is always there, whilst F is no problem when the seeing is at its best. The main stars in the trap have been such tight disks that it has made life much easier.

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Seeing, seeing, seeing!

Same for me - if the seeing is excellent then E & F are no challenge provided the mag is kept low enough. I've had the most wonderful views recently using my 180 Mak with a 38mm Panaview; the whole of the nebula is visible with the Trapezium in the centre, with E&F showing clearly. With my smaller Mak, it is more difficult but can still be done on nights of excellent seeing.

Chris

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On 12 January 2013 at 11:53, Peter Drew said:

It's very much a question of good transparent seeing. With my C8 in Tenerife E and F are so easy it's not a test, yet in the UK it's often difficult to see them both in a 16" SCT. :smiley:

I would agree, I can see E and F in my CPC 1100 almost all the time in magnitude 4.5 to 5 skies. I am at 2500 meters so I imagine it is the seeing that is important. I posted a picture taken with a DSLR in the Deep Sky Imaging section a few week back, though I don't know how to link to it. 

 

Here's the link Beka...

 

Stu

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20 minutes ago, chiltonstar said:

Seeing, seeing, seeing!

Same for me - if the seeing is excellent then E & F are no challenge provided the mag is kept low enough. I've had the most wonderful views recently using my 180 Mak with a 38mm Panaview; the whole of the nebula is visible with the Trapezium in the centre, with E&F showing clearly. With my smaller Mak, it is more difficult but can still be done on nights of excellent seeing.

Chris

That must be quite something Chris, the wide field plus detail all at once, amazing. I had not realised the significance of the jetstream until relatively recently. What a difference it makes when it clears off!

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I also find the seeing to be the most important factor, can usually get E star from central London with my 8" newt and bortle 8 skies, but usually only when the seeing is fairly steady. Never seen F though (however I've never yet had my scope out to a dark site so there is hope!)

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14 minutes ago, CraigT82 said:

I also find the seeing to be the most important factor, can usually get E star from central London with my 8" newt and bortle 8 skies, but usually only when the seeing is fairly steady. Never seen F though (however I've never yet had my scope out to a dark site so there is hope!)

I got them both in the 4" from a Bortle 7 site so I'm sure with the right seeing, collimation and magnification you should be able to get F where you are.

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7 hours ago, PHIL53 said:

I do agree that seeing is the most important ingredient and, do not know why,  always found easier to catch E rather than F...

E is definitely easier than F, I agree Phil. I think it's because the star it is next to is brighter so it is harder to separate it from the glare.

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I've seen E & F occasionally with my 4" refractor, regularly with my 4.7" refractor and they are very clear and bright with my 12" dob (not suprisingly !).

Sometime back I found that getting the magnification right was the key to easing the challenge. The "goldilocks" eyepiece can vary depending on the conditions but often I find that the 8mm Ethos is the one.

More magnification does not always help with these little blighters !

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I've seen E with my 250px, and my light pollution is far from ideal, but I've yet to find F mostly because I keep forgetting where it is to do a proper look for it. One day I'll remember to make a sketch. I last saw E a few weeks ago, it was fading in and out quite a lot.

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Just now, John said:

E & F were quite clear last night with my ED120 refractor. The "magic" eyepiece last night was an old Meade 4000 6.7 UWA for 134x - very nice Japanese glass !.

 

Nice John. Skies looked great last night but no 'observing pass' for me unfortunately ?

That sort of mag seems to work well doesn't it?

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  • 1 year later...

Old thread. But just had to say I had my first night out with a new SW 120ED Pro this evening and managed to pick out both E and, for the first time ever, F. Used a 4mm TMB/Burgess eyepiece for x225. Never managed to see the F in my 10" Newtonian, although that scope never seems to be quite there for higher powered viewing and I could never use the 4mm in it.

The moon was just breathtaking as well. Contrast and sharpness were the best I have ever seen, giving a real feel of texture to the Apennines.

The optical quality of this scope is way better than anything I have used before.

Happy bunny. :icon_albino:

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On ‎26‎/‎02‎/‎2016 at 15:53, beka said:

I posted a picture taken with a DSLR in the Deep Sky Imaging section a few week back, though I don't know how to link to it. 

 

Here's the link Beka...

 

 

This^^^ is the most useful thing I've seen so far in my hunt for these.  I've looked at the picture and I think can see the two stars - are they the ones at the 'inner' end of my pink lines please?  If so then I think now I know what to look for - sometimes these 'double' stars are dead simple to split, like Castor - which I read online does have another 4 stars hiding around A and B - The A and B of castor are two bright pinpoints of light, clearly a double with good separation.  Many are less clear than I think, i.e. what am I looking for something faint, something bright, how far away are they?  Will there be a clear split, I'm like this with something like Polaris.  I have looked at all the diagrams for the trapezium and still haven't known what to look for there is no substitute for something like that photo though - now I know instantly what to look for and I bet if I get a night of good seeing I will now have no trouble finding them (assuming my lines are correct).  Many thanks for that photo.

 

 

E and F.jpg

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Yes, your lines are correct.

I only have a 4" scope to look at them currently, in which E has good separation and shows as a very faint star, often coming and going with the seeing. f is much more of a struggle and seems closer to its primary. I get hints of it now and then but never a clear split in that scope. A lot is to do with seeing and LP. A steady dark sky should help with both.

The best view I've had, bar none, was with Gavstar's TEC160. This blew into the water any view of them I've had before, even in a good 12" dob. Both stars were just 'there', tight and bright and clear separation, no messin' ;). Lovely! 

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1 hour ago, Ibbo! said:

C11

That's a whole 3" more clout than I've got, mind you if Stu can get them with his 4" (though it is a Tak) I guess I ought to stand a fair chance with the 8" 200P esp, now that I know what to look for.

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23 minutes ago, JOC said:

That's a whole 3" more clout than I've got, mind you if Stu can get them with his 4" (though it is a Tak) I guess I ought to stand a fair chance with the 8" 200P esp, now that I know what to look for.

I have done E with my 4" Tak from here  and I think F as well the memory is going.

And yes I have done then with the 8" Meade SCT.

 

Seeing is the key.

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3 hours ago, JOC said:

That's a whole 3" more clout than I've got, mind you if Stu can get them with his 4" (though it is a Tak) I guess I ought to stand a fair chance with the 8" 200P esp, now that I know what to look for.

I can see them with my 8" dob. You shouldn't need to know "where" to look, you should just be able to see them given the right magnification to separate the stars and darken the background. 

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