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Trapezium E & F stars


Doc

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Do you guy's think I should be able to see stars E and F in the Trapezium from my light polluted backyard using a 16" lightbridge dob.

Just wondering as it will soon be time to get viewing M42 as it's getting pretty high now.

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Get a map of the trapezium so you know where to look (they are both near brighter stars and can get swamped), wait for good seeing and put the power up to around x200. I'd be surprised if you skies were that bad that a 16" scope couldn't pick them out, I have decent, but not great, skies and a 6" refractor shows them on good nights. I've heard or people bagging them in 4" scopes but I've yet to try it in anything that size.

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Cheers Gaz I've never seen them before so this is my goal for winter.

I'll be shocked if in good seeing these stars do not appear.

Thanks Talitha this is really helpful. Might even try for the G & H.

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I've seen the E & F componants with my 8" F6 dob from my back yard and I've got some light pollution problems as well. They are not easy but with patience and good collimation they appear as tiny "sparks" of light. I felt quite a sense of achievement when I spotted them - I had previously only seem them with a 10" scope.

John

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I can usually see the E star with my 10" reflector from my dark sites and my home (in a large town). I've only once seen the F star though and that was from a dark site on a night of very good seeing (all too rare...).

I think seeing plays a more important role than pure aperture although having a 16" scope must help!!

James

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As well as good viewing conditions I think good collimation is also important. The E &F stars are pretty close to other much brighter stars ( A and C ) and embedded in nebulosity so you want nice tight star images to clearly pick them out.

JOhn

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I'd agree with you John, collimation is important for this target! My collimation is usually spot on so I have a sneaking suspicion that my eye may be at fault for not seeing the F star more often. I'm looking forward to another clear night to give it a go again.

James

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F is the trickier of the 2 as it's next to the brightest star in the group C. Also, it seemed to me, when I looked a couple of weeks back, to be a little closer to C than the chart above indicates - closer than E is to A.

You'd need some seriously large aperture to see G & H. Might be do-able with a 16" from a dark site but the theoretical limiting magnitude is 15.7 for a 16" so a 20" would probably be required.

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While doing supernovae seaching with 12" f5 newt I could get down to 15.5 mag. The trick is to use enough magnification to give a dark background..... controlled breathing and start with averted vision....

A 16" should easily show these stars.

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... Also, it seemed to me, when I looked a couple of weeks back, to be a little closer to C than the chart above indicates - closer than E is to A.

I was thinking that myself Ian... hopefully I'll get a clear night soon to check.

James

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... Also, it seemed to me, when I looked a couple of weeks back, to be a little closer to C than the chart above indicates - closer than E is to A.

I was thinking that myself Ian... hopefully I'll get a clear night soon to check.

James

I'll be having another look too - hopefully the clouds will clear before chrimbo :hello2:

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Coincidently I'm reading Agnes Clerke's " Popular History of Astronomy in the 19th Century". On page 142 she notes the discovery observation of the sixth star in the trapezium, by Sir John Herschel using James South's 12" refractor on the evening of the 13th February 1830.

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Sir John Herschel rated the F star as a fourteenth magnitude object, by 1870

Norman Lockyer tells us that it was observable in telescopes of less than 4 inch

aperture (90mm). In the past, the F star has been suspected of being a FU Orionis

type variable that brightened in the nineteenth century.

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I got out last night and what looked unpromising (strong winds and madly twinkling stars) turned into a success as I was able to see the F star. I was using my 10" at 120x. The F star looks much closer to the C star than the map Carol posted but I'm wondering if that's just a consequence of the large magnitude difference between the C and F stars.

Had a go with a 120mm f/8 Achromat in the early hours this morning, managed to pick up star F at 166x.

I forgot to take my ED100 out to see if I could find it... :)

James

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