The trapezium with a fairly big Dob

[Paul73]

SkySafari Pro 5 shows them all, including G at mag 16.7

Just me being a bit thick then. I hadn't twigged that the "G" in STF 747 G 7.7" was referring to the Trapezium G.

Hoping to get at least 1 more view of M42 before Summer.

Paul

[John]

This is the weblink that I sent to Alan:

http://www.sydneyobservatory.com.au/2010/harry-zooms-in-on-the-trapezium-the-heart-of-the-great-nebula-in-orion/

Mind you, the magnitude of G seems to be shown differently from SkySafari

[alan potts]

Goes to show what my memory is like, I put in the report i1 and i2 when it is really H 1&2.

I have the book that Stu was copying from and there is refrers to an X star, sort of x marks the spot where clearly dark forces are at play. Only one man having seemimgly seen it and not in anyones lifetime.

Going over this Exit Pupil theory.

Am I correct exit pupil equals objective divided by magnification ie 100mm/x100 = ep1mm

The Meade at 305mm dia is best with the 24mm Panoptic giving a power of x127 and expu of 2.4mm

On the APO it is best with the power around X100 with an 8mm eyepiece which is an expu of 1.15mm and I have seen both with this.

On the Mak 180mm with it;s 2700mm F/L I tend to again go for the 24mm, an expu of 1.6mm

finally on the M/N 190 at 1000mm either the 10mm or 8mm come into play which is an expu of 1.9 or 1.5mm

The Sumerian with 458mm F 4.33 mirror with Paracorr was cleanest and for me best with the 17mm E at X134 which is an expu of 3.4mm It was even beautiful with the 21mmE where the expu would be even higher.

I found these to be my best views of this object (Easier split of E&F) many times on the first 4 scopes, and I believe this is what John was telling me and I would say there is not much of a link in the exit pupils, bear in mind from my experience the E and F stars are very difficult above these powers except with the 18 inch, this seemed to be failing more because of conditions than anything else.

Maybe we could say it is best viewed with an exit pupil between 1.0mm and 2.5mm which for me is not very precise as an exit of 1.0mm with either the Mak of the Meade gives power  X270 and X304, on these two scopes. On both I have never seen the trapezium split of E and F above about x160 and less was always better as I have just tested albeit with the M42 fairly low down but conditions are by no mean bad.

Alan

[John]

I've always tended to find the 8mm focal length seems to be the "goldilocks" eyepiece for E & F with my F/5.3, F/6.5 and F/7.5 scopes so thats an exit pupil range of 1.06mm to 1.6mm. I have seen them with other eyepieces but the 8mm just seems to let them "pop" just a bit easier.

[alan potts]

Pop is a very good word for it as they sort of POP into view, again there you are with low readings with regards to exit pupil. Personally I don't see there is an optimum reading as taking either of these applied to the Meade just don't work, maybe for other reasons but they don't.

alan

[Stu]

Good thread here, anything past F looks pretty tough

Trapezium in Orion by ASI120MC

http://stargazerslounge.com/index.php?/topic/258720-Trapezium-in-Orion-by-ASI120MC

[alan potts]

Stu,

Anything past F looks tough, I agree they appear to be beyond the normal sort of scopes we have, I don't even think an extra 2 inch would help though there are a few on site with larger telescopes. When you read as I am sure we both now have words like "glimpse" with 3 feet of mirror, then I imagine I am hoping for magic. The other thing to consider is where it was Texas where apart from the dry air at times of year, Orion would be pretty much overhead.

I will try again if only to look at M42, it really comes alive with a big mirror and when the seeing allows the detail that comes out with this Nichol mirror is amazing, I may even have a tad more contrast over Calvin as my secondary will be a little smaller than his, though at this size I bet few could see it.

I was being to feel I could see a star outside of the trapezium that you can see in the photo but was not sure, could just have been wishful thinking.

Alan.

[estwing]

My secondary is 90mm Alan...

[alan potts]

Calvin,

I do not have a clue what mine is but at a guess I would say it was smaller. You scope is F3.9 mine is F4.33, at most it is going to be 10mm smaller and I would not have thought thats make too much difference in 458mm.

All the best for New Year

alan

[DRT]

I have the book that Stu was copying from and there is refrers to an X star, sort of x marks the spot where clearly dark forces are at play. Only one man having seemimgly seen it and not in anyones lifetime.

I have been looking at that chart for ten minutes and for the life of me I cannot see an "X"

The weather forecast for 31st Dec is looking favourable here so I might pull out the 16" Dob and spend some time trying to find these little gems

[alan potts]

Derek,

Me to, that is why I looked in the book and there is an X on that chart p175 but I have newer copy, bit misleading of me, I'm getting to good at doing that by accident lately.

I think to see them our Dobs need to put on weight, alot of weight.

Alan

[estwing]

Wonder if Simons give this a bash with his 22" Nichol?

[alan potts]

Well it's always worth him having a try but as I said eariler in the thread Texas is a place where Orion will be overhead, seeing is possibly better as the air is drier there and 36 inch is a big mirror and I didn't like the word glimpse.

I can live without the fainter stars but I can't wait to get Orion in pole position for me and have another session on M42 and of course the Horse's Head, IC 434 I believe. I know they cost alot and sadly not everyone can justify or afford them but the Ethos is just mind blowing on these big Dosonians, it's almost like they go to a different level as compared to my other scopes. They do go to 11.

Alan

[estwing]

tbh Alan its not until you are lucky enough to see/use/own these sort of tools for observing that the penny finally drops and it all becomes clear why you have just spent a small fortune! The views are simply worth every penny...

[niallk]

Sounds like that 18" Nichol/Sumerian is doing the biz. I'm still awaiting a good night to try for E & F - tbh haven't really seen M42 properly in my 15" yet. Mind you weather & seeing have been just so poor for what feels like months now.

I had one incredible night before with my 10" - beautiful tones of green fibrous nebulosity, and it felt like the trap stars were hovering in front of the scooped scallop shell shape of the neb - a weirdly strong 3D effect - hard to describe & a very surprising new experience after having viewed it tonnes of times for years.

I love the way 'familiar' targets are so worth revisiting time and time again: there is always something to discover on a special night...

[estwing]

I think Frank is putting pay to tonights chances!

[niallk]

I think Frank is putting pay to tonights chances!

Karma will kick in, and we'll all be pushing 1000x on our favourite targets in a couple of weeks...

[DRT]

I tried 1000x this evening and could see fabulously consistent detail in the blanket of grey cloud above my house. Grey right to the edge!!!

[John]

I tried 1000x this evening and could see fabulously consistent detail in the blanket of grey cloud above my house. Grey right to the edge!!!

Yep - cloud soaks up magnification really well

[chiltonstar]

This is the weblink that I sent to Alan:

http://www.sydneyobservatory.com.au/2010/harry-zooms-in-on-the-trapezium-the-heart-of-the-great-nebula-in-orion/

Mind you, the magnitude of G seems to be shown differently from SkySafari

There seem to be some interesting differences in the lit for the magnitude of "G", for example 14.5 as in this article would be do-able in a much smaller scope than the monsters being talked about!?

Chris

[John]

There seem to be some interesting differences in the lit for the magnitude of "G", for example 14.5 as in this article would be do-able in a much smaller scope than the monsters being talked about!?

Chris

Is it a variable perhaps ?

Only one way to find out ...... try for it !

If Orion is still in the sky when the clouds and rain finally clear off that is ........

[alan potts]

I sat and had a good look at the trapezium last night with the Meade 12 inch which can do Mag 14.5 from my site and I didn't see a thing though Orion was not in the best position from here. It was very cold and also very dry, seeing was snappy and toes were chilly.

I was continuing to play with the magnification for doubles E and F both of which could be seen easily at X127, this was not the case as I went to X179 with an 18mm orthoscopic, though I could still see them they were by no means as sharp.

Alan

[chiltonstar]

Is it a variable perhaps ?

Only one way to find out ...... try for it !

If Orion is still in the sky when the clouds and rain finally clear off that is ........

I re-read the article and a few others and if the articles are correct, G is a proplyd rather than a star and therefore the apparent magnitude differences are due to wavelength of observation (G looks brighter when imaged with an IR-sensitive detector than by eye) - no wonder you couldn't see it then Alan!

Chris

[alan potts]

Chris,

I, like yourself have read a few things on the net and from books the last few days and I feel seeing it with any scope I have is about the same chance as Pink Floyd doing a concert in my garden, at least I a 3 phase supply if they do.

Alan 

[chiltonstar]

Chris,

I, like yourself have read a few things on the net and from books the last few days and I feel seeing it with any scope I have is about the same chance as Pink Floyd doing a concert in my garden, at least I a 3 phase supply if they do.

Alan 

If I saw Pink Floyd in my garden, I'd think it was time to switch to a better brand of Shiraz.....

Chris