Trapezium E & F

[gfletcher]

Hi Guys

Just been out looking at M42 through my 10" newt.

My aim was to try and find E & F.

When i put the power up tp X200 with a 6mm ortho

there they were clear as day without having to use averted vision !!

Made my evening as this is the first time i have been able to see them

My previous C8N scope would not show them

Graham

[matt c]

pardon my ignorance mate but whats E & F are they stars or something:icon_confused:

[gfletcher]

Matt

The main stars of the trapezium are A,B,C,D which are quite easy to see through most telescopes.

Stars E&F of the trapezium are much more difficult due to their magnitude and closeness to the brighter 4 stars.

I think E & F are of the 11th magnitude.

Hope that helps

Graham

[matt c]

aahh yes i get it now. i didn't realise you could see more than 4 with a 10" scope definately try that with mine next time

[Talitha]

Congratulations, Graham! The only time i can coax them out of the nebula with my 8" SCT is when the seeing is pretty steady. They're so delicate looking.

[gfletcher]

I was amazed Talitha that they showed up that clearly.

It needed the X200 to show them though.

Graham

[Doc]

Well done on spotting these, sometimes I fail even with 16" of aperture but sometimes they are easy, good seeing is essential.

There are actually more stars take alook at the illustration below.

[Mark at Beaufort]

I must admit I have never seen E and F but following this thread I must give it a go. Very helpful diagram Mick and thanks Graham for the suggestion and well done on seeing the stars in your 10".

Mark

[Steve922]

How many of these have you grabbed yourself, Doc? What sort of magnitude will that beast of yours reveal under really good conditions?

Steve

[Doc]

Steve I have seen E & F on numerous occasions and In theory G,H and I, should also be within the scopes range form a really dark sky with excellent seeing but I have yet to see this. The scope has a limiting magnitude of 16.5 so should be possible.

But I have found that at times my 4" refractor splits double stars alot better then my dob, I don't really rate dobs for star splitting, but for DSO's of course they excell.

[Mark at Beaufort]

Yes I agree with the statement on refractors. I was going to set up the 6" frac and 10" Dob side by side to check whether I could see E and F. Both instruments have the same focal length so the comparison should be interesting.

Mark

[Doc]

I think it's to do with collimation Mark. My Tal refractor has never needed collimating and it splits tight doubles really well.

With a dob you have to factor in collimation, and cool down times. I just never seem to get as clearer split with the dob.

[Towa]

Using a Tak TSA-102 last night, I was able to easily see star E,

while star F would come and go in seeing condtions at around 100x,

but I did get some good views of it during better moments.

[Doc]

Using a Tak TSA-102 last night, I was able to easily see star E,

while star F would come and go in seeing condtions at around 100x,

but I did get some good views of it during better moments.

I have found this as well. Even though E and F are very similar in brightness and distance away from their nearest star, F is harder to see. Surely this cannot be seeing conditions as E is clearly visible and F just wanders in and out of view.

[Towa]

For me using smaller apertures, I found that star F is closer to the bright star C than all the drawings and charts show.

Unlike star E, which is easily seen and quite well separated in my 4 inch refractor.

I think that the brightness of star C also makes F harder to see in my smaller scopes.

Only on nights of really poor seeing do I fail to see star E.

[themos]

Poor seeing last night, also haven't star tested the collimation yet (no good seeing available since mirror wash) but I could clearly see E (12" f/5 newt and 9mm ortho at 166x). I could not see any of the others.

[mdstuart]

Well I can only do E in my 10 inch dob. It is very tough though!

[Mark at Beaufort]

Decided to use the 6" frac tonight to try and view stars E and F. Good clear and steady sky and used mags of 240, 300 and 375. Unfortunately could not detect either E or F. Must try with the 10" next time.

Mark

[John]

I have just come in from a session with my 5" F/9.4 achro refractor and I managed to pick out E and F with a 7mm Nagler @ 171x. E was a little easier than F tonight (it's normally the other way around) with F coming and going with the seeing variations. Definate moments when the Trapezium was 6 stars though and a very nice sight !.

With my 4" ED refractor I've only been able to spot F so 5" is the smallest aperture I've been able to see both.

John

[fmeireso]

Well done on spotting these, sometimes I fail even with 16" of aperture but sometimes they are easy, good seeing is essential.

Dito, Doc, even with 18 inches. That's exactly what i experience too.

[James]

I find the E star much easier to see and usually see it whenever I'm out with my 10" Newt. I've only seen the F star once confirmed and once possible despite excellent collimation. Seeing really seems to be the most important factor.

James

[Mark at Beaufort]

I felt frustrated that I could not see E and F last night. I was pleased that John detected these stars with his 5" last night so I tried to work out this morning why I failed?

I now have a good idea why I failed which makes me feel rather silly. I concentrated on the diagram that Mick (Doc) provided and looked for a star between the two left sided ones and another star top right corner. I now realise that this diagram is the view through a reflector not a refractor using a star diagonal. I was solely looking in the wrong place.

Perhaps I should have another go!!

Mark

[fmeireso]

Seeing really seems to be the most important factor.

James

Yup, that and a properly cooled mirror.

[John]

With a refractor I find that the tight star images help with seeing the E and F componants. Sometimes newtonians and schmidt-cassegrains, especially if they are not quite in 100% collimation, produce star images that are a bit "hairy" - that's enough to drown out these much fainter stars that are close in to their brighter companions.

The ability to split close double stars of very uneven brightness (which is in effect what the E and F stars are togther with the A and C componants) is a stringent test of telescope optics, seeing conditions and the observers eye.

Another good test double of this type is Rigel, also in Orion. The primary star (Rigel A) is magnitude 0.18 wheras Rigel B is mag 6.7 - the pairing is not that close together but the huge brightness difference makes it quite a challenge I find.

[pvaz]

After reading this I tried to see them on my scope. The E star was clearly visible even at 80x but I couldn't see the F star.

I'll have another try when the moon is out. I think my collimation wasn't spot on, I need the laser colli to arrive.