the Trapezium in M42

[RT65CB-SWL]

Ok, so this is an easy target for amateur astronomers, but one that can be ticked off or added to my observing list. I managed to split the 4 main stars. Although I could not see the 'E' and 'F' stars in the Trapezium in M42 lastnight/early this morning form my home location now that my local authority/council are replacing the sodium streetlights and are erecting LED streetlights in the area.

I used my 're-modded' ETX105 mounted on my Giro and Meade 20mm Plossl, then straight onto 6mm LER eyepiece. Very nice and subtle fuzzy grey from M42 itself. I did not use my Baader Contrast or Baader Neodymium filters. I will try again with them and see if they do make a difference and tease out some finer detail. Even though I had a waxing gibbous Moon nearby, I did manage to hide/shield myself away from the Lunar glare.

So LED streetlights have mixed reviews here and there, but I have never before done this split previously under sodium streetlights from home, even with the filters mentioned above. Overall I was very impressed.

 

[Stu]

You can't beat M42 and the Trapezium, lovely target and dramatic under a dark sky.

E & F can be (are!) fickle targets, tricky if the seeing is not stable and quite dependent upon getting the right magnification, not too high or too low.

[GavStar]

30 minutes ago, Stu said:

You can't beat M42 and the Trapezium, lovely target and dramatic under a dark sky.

E & F can be (are!) fickle targets, tricky if the seeing is not stable and quite dependent upon getting the right magnification, not too high or too low.

Interesting point Stu, about not going too high magnification. What range of magnifications have worked for you to see both e and f?

[Luna-tic]

I love looking at this group. I've split A through D, and have seen E as a bulge off A, but haven't seen F. Does it split from C? I was using a 13mm EP and 2.5 Barlow in an Edge 8 to get that.

The streetlights on my road have also lately been changed to LED. Although they seem better shaded than the sodium lights they replaced, the whiter light bothers me more and I have two that I can't block from view using a tree or house.

 

[John]

Nice report !

I agree that E & F can be challenging in smaller apertures. I find my ED120 will show them relatively easily at 180x and above, if the conditions are good. They are quite a bit harder in my 4" refractors. F is made harder by the brightness of C. With my 12" dob at 200x E & F jump right out at you and you wonder how you missed them in other scopes !

I use the visibility of Rigel's companion star and the 10th magnitude member of Sigma Orionis as indicators of how tough E & F Trapezium are likely to be.

Here is the layout of the grouping with the separations and magnitudes:

 

[wookie1965]

I have only ever seen the E and F stars in my now gone 150p a couple of years back on a particularly frosty clear night. In my 200p which I have only had for about 8 months I have not had a really good night yet to try. 

[Stu]

John has said much of what is to be said  

I think the area of x180 to x200 is good for my refractors. Going much higher does not help so much I find. Seeing conditions are key, as is collimation and cooling for Newts/SCTs.

Like others I find the E star easier than F. To me it appears separate from A and B but tends to flick in and out of visibility  as the conditions vary. F is more buried in with C and is one that I rarely see.

[John]

Interesting piece from the Sky & Telescope website on the Trapezium and the area of M42 that it sits within here:

http://www.skyandtelescope.com/observing/star-trapping-in-orions-trapezium/

At mag 13.8, in principle I should be able to get "G" with my 12" dob on a decent night. The "H's" and "I" are going to be a bit beyond my scopes though at mag 15 ish

[chiltonstar]

Always a good test of seeing and accuracy of focus! Slightest error in focussing and E and F disappear I find. 

10x easier with my 180 Mak than my 127 Mak (119mm true aperture).

Chris

[RT65CB-SWL]

Thank you for your comments chaps.

I will definitely have a go at the 'E' and 'F' stars when the Moon is not up with the ETX again, (and also with C6 & TV Ranger). Some years ago at a star party I attended, someone said they could see 'them' with averted vision when they had a look through the TV Ranger coupled with my 6mm Radian e/p. I did not have the ETX or C6 back then.

[John]

I got E quite frequently tonight with my 100mm F/9 Tak flourite. F occasionally. Best mag seemed to be around 180x (5mm Pentax XW).

 

[chiltonstar]

7 hours ago, John said:

I got E quite frequently tonight with my 100mm F/9 Tak flourite. F occasionally. Best mag seemed to be around 180x (5mm Pentax XW).

 

Interesting that you could see both with the 100mm fluorite - I'll try with my 102mm Vixen achro, although the contrast will be less, which is I suppose a significant issue against the nebula background.

Chris

[John]

5 hours ago, chiltonstar said:

Interesting that you could see both with the 100mm fluorite - I'll try with my 102mm Vixen achro, although the contrast will be less, which is I suppose a significant issue against the nebula background.

Chris

Yes Chris, I agree that the nebulosity does play a part in making these challenging with smaller apertures. It might also explain why there seems to be a "sweet spot" of effective magnification for teasing these little fellas out. Too little and they are indistinct and unresolved, too much and they blend into the background sky. 

 

[alan potts]

23 hours ago, John said:

Interesting piece from the Sky & Telescope website on the Trapezium and the area of M42 that it sits within here:

http://www.skyandtelescope.com/observing/star-trapping-in-orions-trapezium/

At mag 13.8, in principle I should be able to get "G" with my 12" dob on a decent night. The "H's" and "I" are going to be a bit beyond my scopes though at mag 15 ish

I had no luck at the extended alphabet last year having spent a good few nights, quality nights too, looking with the 18 inch,  I found the centre of M57 easier to be honest, picked it up again the other week, but it is overhead at the moment.

Alan

[chiltonstar]

At mag 13.8 or a little higher, depending on source, G could theoretically be seen by an experienced observer with a smaller scope, if you believe the various papers and observations on the topic. Something to try for.....

Chris

[niallk]

Is part of the problem in seeing >F contrast against the background nebulosity, rather than absolute magnitude?

I never saw E & F in my 10" tbh, first seeing them in my 15". F ain't easy...  Good seeing is important it seems.  I must go back and try for them in my 250px...

[John]

2 hours ago, niallk said:

Is part of the problem in seeing >F contrast against the background nebulosity, rather than absolute magnitude?

 

Partly I think, plus it's close proximity to the brightest of the 4 main Trapezium stars, C. A big brightness difference makes double stars harder to split so this plus the nebulosity makes F a tough nut to crack.

 

[Piero]

5 hours ago, niallk said:

Is part of the problem in seeing >F contrast against the background nebulosity, rather than absolute magnitude?

I never saw E & F in my 10" tbh, first seeing them in my 15". F ain't easy...  Good seeing is important it seems.  I must go back and try for them in my 250px...

I regularly see E and F with the 8" in Italy, so your 10" can certainly do it. I don't use too much magnification though. I think about 130x and 150x. Need to check my notes. I found that a steady night really make the difference. 

Never succeeded with spotting E with the TV60 though. Hopefully the Tak will this winter.. finger crossed.

[Alan White]

I got my first Orion last night while christening the 10mm XW and with my ed80 could not resolve the e or f, but I never have from my home location fully even with the ed100. 

Seeing was so so last night so not the night for achieving this challenge, but the 10mm XW produced a real inky sky that I have not achieved before.

[alan potts]

5 hours ago, Piero said:

I regularly see E and F with the 8" in Italy, so your 10" can certainly do it. I don't use too much magnification though. I think about 130x and 150x. Need to check my notes. I found that a steady night really make the difference. 

Never succeeded with spotting E with the TV60 though. Hopefully the Tak will this winter.. finger crossed.

I too have picked these up many times with my M/N 190mm and Mak 180mm, I do feel though our sky is a bit better than in England, as well as the target is at least 11 degrees higher in the sky, this must make a difference.

[Mr niall]

Not had a go at the trapezium yet, will definitely add it to my list! Many thanks for the report.

 

[John]

18 hours ago, Alan White said:

I got my first Orion last night while christening the 10mm XW and with my ed80 could not resolve the e or f, but I never have from my home location fully even with the ed100. 

Seeing was so so last night so not the night for achieving this challenge, but the 10mm XW produced a real inky sky that I have not achieved before.

I find F pretty challenging with a 4" aperture. It's a bit of a "red letter" night when I spot it with that aperture. 120mm makes it somewhat easier but you still need decent seeing and to play around with eyepiece focal lengths to find the "goldilocks" one for the conditions.

With my 130mm refractor and the 12" dob (especially the latter) E & F are a bit more routine.

[John]

29 minutes ago, John said:

I find F pretty challenging with a 4" aperture. It's a bit of a "red letter" night when I spot it with that aperture. 120mm makes it somewhat easier but you still need decent seeing and to play around with eyepiece focal lengths to find the "goldilocks" one for the conditions.

With my 130mm refractor and the 12" dob (especially the latter) E & F are a bit more routine.

This said, I've been able to see E & F with my Takahashi FC-100DL tonight. F was the more challenging and popped in and out of view. 125x seemed to be the "goldilocks" magnification tonight.

[alan potts]

Looking at the extended picture of the alphabet stars and taken that seeing is all important I do wonder why I have seen so many different magnitudes for G, H and I. I trust John in that he tells us one of them is recorded at mag 13.8, therefore should be possible with my 18 inch, even my 12 inch from what is a dark site, but I am yet to see anything in these area even with averted imagination. I do sometimes wonder about the printed word in these cases.

Alan