Seeing Orion Trapezium stars E&F - tips

[Eastridge]

Hi,

A recent Telescope House newsletter mentioned looking for these, which it says are mag 10, so we had a quick go last night. Can easily see Trapezium A - D with 8 - 3mm in our 250 PX but no sign of E&F.

My first thought is that maybe we need a darker site? Home is (I think 5-6) on the bortle scale.

Does that sound like it or is there another factor people can think of?

[VigdisVZ]

I only saw 4 last friday with my 6 inch, but some of my buddies picked out 5 with the clubs 18 inch. I'd say aperture and good atmosphere and darkness all help.

[wookie1965]

Thats strange i can see all the stars of the trapezium with my 150p with 8mm BST in medium light polluted skies quite easy.

[Zul]

I can see all 4 stars with 80/400 refractor just need to get excelent focus.

[Eastridge]

Sorry guys wasn't specific enough - yes I can see the main 4 ( A-D) fine with 8-3mm.

But it's seeing the 5th and 6th ( E and F) that I was trying to do. If someone says it's impossible with 10" I'll forget it but if 10" would be enough on a dark site / with good seeing I'll keep trying.

[Zul]

I thought there is just 4 stars . Maybe someone can link me any image that shows all thouse stars?

[wookie1965]

No with a 6 inch you can see up to i think its 12 mag in good seeing as e+f are 11th mag they should be easy in a 10inch as that can see 14 mag.

[coulthamst]

I managed to see the E and F stars of the trapezium clearly last year from my seriously light polluted position just one and a half miles from the centre of Leeds, using my Skywatcher 8" flextube dob. I made a sketch of what I saw at the time to compare with a published position drawings of the six stars in the group to confirm what I had seen. Sky conditions here have never been better to my knowledge than naked eye mag 4.1 since I took up astronomy again some twelve years ago. Presumably the seeing that night was particularly favourable. Goes to demonstrate that the old advice to keep trying is valid.

[wookie1965]

I thought there is just 4 stars . Maybe someone can link me any image that shows all thouse stars?

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

Here you go

[Eastridge]

Zul

the thing that bought them to my attention is here: http://www.telescopehouse.com/acatalog/Telescope-House-Monthly-Sky-Guide.html

For more try this:

http://www.google.co.uk/imgres?q=orion+trapezium+stars+e+f+image&hl=en&sa=X&tbo=d&rls=com.microsoft:en-GB:IE-Address&rlz=1I7WQIA_en-GBGB511&biw=1280&bih=929&tbm=isch&tbnid=Qf6vOtrtnxSqPM:&imgrefurl=http://en.wikipedia.org/wiki/Wikisource:Telescopic_Research_on_the_Nebula_of_Orion&docid=RDXtbIWXCLUleM&imgurl=http://upload.wikimedia.org/wikipedia/commons/thumb/7/7d/PSM_V05_D277_Nebula_orionis_1834.jpg/350px-PSM_V05_D277_Nebula_orionis_1834.jpg&w=350&h=375&ei=E_fvUPOSLseO0AXG6YGQCA&zoom=1&iact=hc&vpx=630&vpy=208&dur=2271&hovh=232&hovw=217&tx=116&ty=127&sig=104547633301778186730&page=1&tbnh=142&tbnw=133&start=0&ndsp=35&ved=1t:429,r:31,s:0,i:181

[wookie1965]

Wait for a good clear frosty night and you will see them easy in your scope.

[nightfisher]

The trapezium E and F can be hard to see, you need a decent aperture and very dark skies

[Zul]

Thanks. I think its not possible to see them with 80mm refractor but i will try when it will be a clear night.

[VigdisVZ]

Yeah, after reading this thread I think that the 18" probably got the 6th, and I might have gotten 5 if i fiddled more with focus and higher mag... but seeing might have affected it as orion was (usually is) pretty low at it's highest point from sweden.

[Stu]

It is alot to do with seeing, scope cooling and collimation. You also need to use just the right amount of magnification. I have seen E and hints of F in 8" mak but it is difficult. I was looking over/between houses so not ideal. Should be quite do-able in a 10" given the above conditions being right.

Stu

[Moonshane]

I think that seeing, the declination of the constellation and the exit pupil size will allow these to be seen more than the aperture or type of scope. I can see both E & F in my 6" f11 on good nights. don't push magnification too much either, I am sure my 18mm BGO (now sold) revealed them at about 90-100x in my two scopes. certainly at least one of the two 'others'. not looked this year due to apalling weather.

[acey]

The issue with the fainter members of Theta Orionis (i.e. not the 4 trapezium stars A,B,C,D but the rest - which go up to I) is not just their magnitude but rather their proximity to the brighter stars. In other words it's a matter of resolution, not just light grasp. So steady air and good clean optics are important as well as aperture, with high magnification being required.

Star E was discovered by Struve in 1826 using a 9.5" refractor, F was discovered by Herschel in 1830 using an 11.75" refractor. G and H were discovered in 1888 using the 36 inch refractor at Lick Observatory, by Alvan Clark and E.E. Barnard. The latter subsequently found H to be double (mag 14.5 and 15.5m, separation 1.6 arcseconds).

[RikM]

I have seen E but not F with my 10". My local seeing is generally quite poor though. There are two carparks E & SE of me that radiate heat away in plumes, so I have to catch things at just the right time to get good resolution. My Planetary views are similarly limited.

[Jason D]

I typically can see E & F with my 10" dob from my California light polluted backyard skies. It mostly depends on seeing conditions. Attached is a single frame photo I took afocally with my hand-held iphone. You can clearly see E & F. The view at the eyepiece looks much sharper than the attached photo.

Jason

[Crimson Sunset]

I must be incredibly lucky! I managed to see both E and F the first time I tried, using the 250PX from my light polluted back garden (living in a large town only a handful of miles from Glasgow). Good collimation and sky conditions are most likely key although I've not looked for E and F since last year so I can't remember how often they showed themselves and under what conditions! I'll be sure to have a peek next time the seeing is good.

[LeeB]

Hi i've only managed e and f properly on one occasion with a 10", i found it easier with slightly less mag on that night(still high) (i didnt make great notes that night so can't ellab.)

On other occasions I think i glimpsed them but its at the point where i don;t trust myself.

[Jason D]

G and H were discovered in 1888 using the 36 inch refractor at Lick Observatory,

I fly over Lick Observatory frequently. Attached is a photo I took last year.

[Eastridge]

Thanks for all the replies guys, really good to know that it's certainly possible with our scope and I will persevere to get the right conditions etc. taking into account the advice above.

Plus I have noted that I was inaccurate to call them Trapezium E&F, should be Theta Orionis E&F as only A-D are the trapezium, makes sense, thanks acey.

[Space Dragon]

Have seen E with a 9.25" SCT in average conditions from a suburban site, so F should be doable under dark skies and good seeing.

[Peter Drew]

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.