The trapezium with a fairly big Dob

[alan potts]

I find this little collection of stars within Orion's famous sword and Messier 42 a very moreish target and why not it is easy to see in even the smallest scopes, even in the finder. There is no doubt though the larger the objective or mirror the more you are going to see. So last night being beautifully clear, calm and not too cold, set out to try to find the other fainter parts of the trapezium.

It goes without saying stars A,B,C, and D with the 18 inch mirror are very easy at any power and seemingly even when the constellation is fairly low down, having just cleared the nieghbours barn roof there they were as bold as brass. He has recently cut back a walnut that overhung his property and that has helped a good deal seeing low down in this direction, even though the tree is on anothers land but when there is no one there, who knows and last week the chainsaws were out with me cheering him on from behind closed doors.

Using the 31mm Nagler and the Paracorr the scope gives a power of X73 and over a degree of actual field, I have longer focal length eyepieces but the exit pupil becomes very large. Having now well cleared any roof and trees the E and F stars were plain as day, this is something that before using other scopes was not the case, these two generally opening up to view at powers in the range of X100-130, on many occasions over this threshold they were lost too.

It was fellow Moderator John that first opened my eyes in that direction and it has been remarkably true with other scopes, however this one is a fair bit bigger. It is because of that I wanted to try to see the other collection of stars in this group, imaginatively called G, H i1 and i2. Thinking that the alphabet stars were within the scope of the Sumerian Dob I set about hunting, I have to say not really knowing where they were and at the 15th magnitude was not going to be a given without a fight. An increase in the power was require to stand even a remote chance of such a feat so I first tried the 17mm Ethos which delivered, X134, E and F still standing out really clear but no sign of any other letters. I was not able to detect any colour within the clouds which I feel I have done before but things can only get better as the months go by.

It was becoming clear that this nebula which now filled the field of the eyepiece was much more extensive than I had seen beforehand, I had used the scope on this object earlier in the year in March when the whole of Orion was past its best and on the verge of setting an hour after darkness. Site member and fellow 18inch Nicholonian Calvin had warned about this and it was following his lead I when to firstly to X176 with the 13mm Ethos and then onto X229 with the 10mm, he worded it I was fed up with the view increase the power or words to that effect. I was seeing things that I had only before seen in photos and this was way before the object was anywhere near to best place in my sky, which happens about 3 hours later. Try as I did the alphabet stopped at F though I could clearly see stars in other parts of the nebula that I do not believe are connected to the trapezium. Sadly my English is no way good enough to convey to you just how this looked with this scope, it was truely jaw dropping and making me go a little weak at the knees, or is that just old age and cold. A local stray dog was yap yap yapping away somewhere over to the bottom part of my land and he had not even looked through the scope, or maybe it was one of the night befores cats up a tree.

Following the observation I had asked the former mentioned Moderator if he would link me a chart at to where the star gang hung out, this he kindly did only for me to find I had been looking in the wrong places. I then read a post this morning from Big Stu that tells me that a guy in the state of Texas managed to glimpse this G star with a scope twice the size of mine, you know one of those measured in feet, so maybe I am banging my head against a wall here. I will try again for sure but following the new information am not going to hold my breath, though I have heard said this can improve your vision, albeit shortly before you drop dead.

I really hope the UK gets some clear weather soon to allow other site members to get out and have a look at this beautiful object which I am sure many have before even if for us the alphabet stops at F.

Alan

[chiltonstar]

It's a wonderful object in any scope isn't it, with one of the few background DSOs that actually appears coloured to the eye?

Chris

[michael.h.f.wilkinson]

Nice report. I have certainly seen E, and I think I have glimpsed F, but the others are well beyond my scope. Might try one day if I spend some time with Olly's 20" in winter.

[Stu]

Nice report Alan. I bet the views are stunning. No harm in looking for the other stars, it just gives an excuse to spend more time on this lovely object!

Here is a link to the google books copy of the Stephen O'Meara book (well worth buying in my opinion)

https://books.google.co.uk/books?id=FxcrAwAAQBAJ&pg=PA172&lpg=PA172&dq=stephen+o+meara+messier+objects+babara+wilson+texas+172&source=bl&ots=XNU8Ro9QC1&sig=orurBFg32gdUVFT1s5EcoSyWvAg&hl=en&sa=X&ved=0ahUKEwikuJjwmf7JAhVEvHIKHb-bAQ8Q6AEIHTAA#v=onepage&q&f=true

P172 covers the Trapezium

I've seen E & F but always find E the easier of the two, particularly in smaller apertures (4 to 6")

[alan potts]

Michael,

I am sure it is only conditions and latitude but E and F are fairly easy to see with my 190mm Mak Newt and even the 180mm Mak. I believe John has done both with his 120mm refractor, power I feel is the key if the others are in the bank.

[michael.h.f.wilkinson]

I just went through an earlier observing log and did see F fairly easily, even under sub-par conditions (haze).

[chiltonstar]

For me, "eye training" was the issue with E and F. With a 127 mak, I struggled to see them both first of all, and then they became easy with practice. With my 180 Mak, both were obvious and easy at first sight when the mag was right. Given some clear skies (maybe a forlorn hope) I'll try for the more difficult compnaions (thanks for the chart Stu).

Chris

[Mark at Beaufort]

Great report Alan. I have seen stars E and F in a 10" Dob but the thought of viewing M42 with a very large Dob would be wonderful.

[philj]

Good report. I too enjoy the trapezium as a target and this time of year the E&F stars are a good indicator of the atmospheric conditions with my 5" refractor. Good conditions they are easily detectable but lately with the jet stream playing havoc with UK seeing when we get a clear spell they are very difficult to spot, only popping into view in brief moments of steady seeing

[Pig]

Great report Alan, keep them coming as it gives us something to read whilst we are waiting for a break in the cloud ( albeit a very big cloud  )

I haven't looked for the E & F for some time but I will give it a shot when the next opportunity arises..... I don't hold out much hope for the 80mm but I might get lucky with the 150 SCT.

[laudropb]

Very nice report. A most enjoyable read. I have seen E fairly easily in my 8 inch Dob, but none of the others.

[alan potts]

Shuan,

I think tonight may well be my last night of clear weather as things are forecast to change   though my next to useless 200 euro Bresser weather station seems to think otherwise .  I don't know if I will be out tonight as Man Utd :eek: need my help even if they can't hear me, there is life outside astronomy here though I wasn't thinking that way with 23 nights of cloud a while back.

I hope all of you get some clear sky soon, my New Year wish.

Alan

[Pig]

Shuan,

I don't know if I will be out tonight as Man Utd :eek: need my help even if they can't hear me.

I hope all of you get some clear sky soon, my New Year wish.

Alan

I wouldn't hold your breath Alan the game against Stoke was the worst I have seen Utd play for some time..... very little effort was put in. Having said that we have been spoilt for the last 20 years or so and there are bound to be some lean seasons thrown in.

I hope your wish granting works too

[John]

Super report Alan. I'm glad the little chart was some use even though F was the limit on this occasion

One of my lessons from 2015 is that to see the faintest stars and other point sources with my largest scope, high magnifications, really high, do make a real difference.

Next time I get a clear night (assuming thats still while Orion is in the sky ) I'm going to try 400x and 500x on the Trapezium and see what I can winkle out of the nebulosity. I doubt I'll get beyond F (which is pretty routine in my 12" scope on a decent night to be honest) but as has been said, having a really tough challenge seems to make you more acutely aware of other details that you have hitherto overlooked

I'm going to have another bash at the central star in M57 using this approach later in 2016 too. I'm reasonably sure I detected something there this year but I need confirmation for peace of mind. Given that M57 is often seen as a relatively small object against a large starry field, observing it at 500x or more is interesting because it fills more than half the field of view.

[Astro Imp]

Great report Alan.

The trapezium really is an observing treat. With my little 6" Newtonian the four main stars are routine and E is doable on a good night, not managed F yet but will have a 10" Dob. shortly and look forward to give it a crack.

Good luck for the new year.

[alan potts]

Super report Alan. I'm glad the little chart was some use even though F was the limit on this occasion

One of my lessons from 2015 is that to see the faintest stars and other point sources with my largest scope, high magnifications, really high, do make a real difference.

I'm going to have another bash at the central star in M57 using this approach later in 2016 too. I'm reasonably sure I detected something there this year but I need confirmation for peace of mind. Given that M57 is often seen as a relatively small object against a large starry field, observing it at 500x or more is interesting because it fills more than half the field of view.

Going away from trapezium and on to M57, this was a real stinker, there was a thread about 3 years back and spent ages and ages looking at M57 before it was seen with a 12 inch. I had an 8mm E giving X358 if I recall but focusing was very difficult on the Meade. I have seen it twice this year with the 18 inch but after maybe 8 attempts, so never a give me but I have not tried as hard.

Alan

[alan potts]

Very nice report. A most enjoyable read. I have seen E fairly easily in my 8 inch Dob, but none of the others.

Take a special note of the power band John told me about, it really makes all the difference, why I don't know as doubles normally respond well to the extra magnification, but above X130ish really seem to wipe it out.

alan

[Stu]

Take a special note of the power band John told me about, it really makes all the difference, why I don't know as doubles normally respond well to the extra magnification, but above X130ish really seem to wipe it out.

alan

Alan, I think it's exit pupil rather than a particular power so varies with scope aperture. 1 to 1.5mm seems best in scopes up to 12" I think we decided?

EDiT perhaps it was more like 2 to 2.5mm, can't recall

[alan potts]

Alan, I think it's exit pupil rather than a particular power so varies with scope aperture. 1 to 1.5mm seems best in scopes up to 12" I think we decided?

EDiT perhaps it was more like 2 to 2.5mm, can't recall

Maybe Stu, it is just that I find it works with my scopes, and not the ExPu, The F/L of my scopes are from 805mm up to 3048mm and the 100-130 rule works on all of them. Not sure why the Sumerian is the odd one out at x230 you could drive a bus between them though I was getting seeing issues on and off but that is a different matter.

Alan

[Stu]

It's not the focal length which matters, it's aperture. x230 in the 18" is an exit pupil of just on 2mm which makes sense.

[Piero]

Great report! 

I also saw E and F with a 8". They were visible at 92x, 125x, and 171x, but the best view was at 125x (1.6mm exit pupil with this telescope / conditions). Seeing was very good. 

Observing targets at very high power can be surprising though. With an aperture as large as yours, I would try 400x - 500x and see what the night can offer on certain targets! 

In the worst case, you just step back to lower magnifications!

[YKSE]

Alan, I'm kind of in agreement with Stu.

Take some of your scopes as an example, 12" Meade (3048mm, f10),  Sumerian (with PC, 2270mm?, f4.5?), 190MN(1000mm, f5.3), focal length wise, Sumerican is closer to Meade, but,  you would find that the same eyepiece should provide about the same optimum view for specific targets in Sumerian AND190MN despite the large focal length difference, while with the Meade, you'll the optimum view for these targets with an eyepiece of half of the former focal length. This is an easier way to choose eyepieces, i.e. exit pupil

[Paul73]

At last a map! Thanks Stu. None of my atlases show A,B,C,D etc. I'm never sure which are which.

Paul

[Stu]

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

[estwing]

very nice report Alan...the weak at the knees thing comes free with every Nichol mirror...this object will get 52" of glass at it in Elan in two weeks,i cant wait!...its a lovely sight with the 21E...but you just have to crank up the power,a thing that Steve has been telling me since I first met him....which does lead to a lot of revisiting of targets to look at them in a different light