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View Full Version : Object of the week January 8, 2017 - The Great Orion Nebula, M42 and M43



Howard B
January 9th, 2017, 11:19 PM
The Great Orion Nebula

Orion
RA: 05 hours 35 minutes 17.3 seconds
DEC: −05° 23′ 28
Emission Nebula

My first look at M42, the Great Orion Nebula, was with a 3 inch f/15 Tasco refractor in a brightening dawn from my front yard in Arvada Colorado sometime around 1968. I think it was early October because I got up just before dawn and M42 was nearly due south, plus it was pretty darn cold.

I expected to see all the wonderful swirls of nebulosity I’d seen in photographs, but because I hadn’t gotten up early enough the bright sky had washed out all but the very brightest portion around the Trapezium. This wonderful multiple star was the most prominent object in my Tasco. The four tiny stars were very close together and were wrapped in a fading mist of nebulosity that was back lit by an increasingly blue sky. Pretty cool, but it was several years before I was motivated to get up early for an astronomical observation again.

With that first look I unknowingly bettered Galileo’s 1617 observation in which he discovered Theta was a multiple star – he saw three stars – but he never saw any of the nebula surrounding them. He didn’t see any in 1610 either, when he first observed this area, so the telescopic discovery of M42 is credited to Nicholas-Claude Fabri de Peiresc, a French lawyer, who saw it in 1610 and was independently discovered by several others in the coming years. Unfortunately all these observations were forgotten for a couple hundred years, and Christian Huygens 1656 observation was credited as the telescopic discovery of M42 for much too long.

The Orion Nebula has long been recognized as a naked eye fuzzy star, which makes writing of its discovery rather like discussing the discovery of the Moon. Even so, given that Galileo looked at it at least twice (1610 and 1617) without noticing the nebula is a comment on the lack of light grasp his telescopes had, and that perhaps his observing environment was light polluted. Or he observed during a bright Moon. Or maybe his eyes weren’t dark adapted enough. Who can say?

Anyway, Charles Messier made the first decent sketch of M42 in 1769 to "help to recognize it again, provided that it is not subject to change with time" and published it in the 1771 “Memoires de l'Academie”. Because M42 is obviously nebulous to the unaided eye it belongs to a small group of objects in Messier’s list that don’t need telescopic aid to be seen. One conjecture is that he included these objects (M42, M44 and M45 – not to mention M31) along with calling out M43 as a separate object from M42 in order to publish the first version of his list with 45 objects. This would clearly beat the 42 objects on Nicholas Louis de la Caille list of southern objects that was published in 1755. Given human nature this seems likely enough to be true.

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Messier used a surprising variety of telescopes through his career, but his favorite was reportedly a 7.5 inch Gregorian reflector that typically operated at 104x. Reflecting scopes of this era had metal speculum mirrors which had much lower reflectivity than today’s telescope mirrors so it’s likely that the light grasp of this instrument was more like a modern 3.5 inch telescope.

In 1754 William Herschel observed M42 as his first deep sky object, and in 1789 he described it as "an unformed fiery mist, the chaotic material of future suns" as seen through his largely unsuccessful 48 inch scope, which also sported a speculum mirror. He was exactly right, but it would be about a hundred and fifty years before his description could be shown to be the true.

Unfortunately William Herschel didn’t make sketches at the eyepiece so we can’t compare what he saw through his scope, but he clearly saw much more than Messier – or most of us for that matter. However, William's son John made what is still one of the most remarkable drawings of M42/43 in 1838 with his 18 inch speculum mirror telescope from the Cape of Good Hope.

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In 1880 Henry Draper used the 15 inch Harvard refractor to take the first successful photograph of M42, which interestingly shows about as much as Messier’s drawing. This says as much about the state of photography in 1880 as it does about Messier’s observational and sketching ability.

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Although I couldn’t locate exposure data for Draper’s photo it was no doubt a long one given the low sensitivity of photographic plates of his era, so the minimal amount of trailing in the star images shows remarkable tracking accuracy and perhaps represents a stiff neck for Draper’s patience at the guiding eyepiece.

I avoided drawing M42/43 for many years because there's so much detail and so few observable winter nights because of poor weather. I've finally committed to making a decent drawing, and when Judy and I were in Hawaii a few years ago we took her 8 inch f/3.3 scope with us and spent three nights on Mauna Kea sketching - among other objects - M42/43. Frankly, the amount of detail I could see from this wonderful observing location wasn't much less that I'd seen with my 28 inch scope at sea level, so there was still a lot to sketch. This is my rough draft with the 8 inch.

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I've since been working on a drawing of this wonderful nebula with my 28 inch but that will take more time to complete. On the very best nights I've seen a few surprising things and I wonder how many others have noticed:

1. A distinct orange color along the straight edge of the shock front of the Trapezium nebulosity.
2. This same orange color due south of the Trapezium stars, about one Theta Orionis length away.
3. The fine, wave-like texture of the nebulosity inside the area bounded by the Trapezium stars.
4. The red color of the E star in the Trapezium.

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There are too many details to list them all, but I am the most curious about these four. If you haven't seen them, well -

Give them a Go and Let Us Know!

Uwe Glahn
January 11th, 2017, 09:39 PM
Great writing Howard. And a reminder the M42/43 is more than a quick closure object for the end of the night.

Mauna Kea and 8-inch widefield sounds great. I guess not at the top but at the visitor center? The sketch looks fantastic and very realistic, al always. The rendering especially within the southern arc looks interesting. Cool result. I can contribute an older sketch with another widefield instrument - an 20x125 binocular. Unfortunately not with that nice rendering technic like in your sketch.

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Like you I'm also in work for a sketch around the trapezium in my 27-inch. I'm not good in seeing colors but I also noticed strong color impressions within the nebula. Dominated as a for me bright turquoise color directly around the Trapezium, some reddish colors could also be detected. With the 27-inch and the 36-inch I could see red to orange color along the "Frons" rim (eastern edge). Interesting fact is that I have the feeling, that the color perception improves with of course the transparency but also the seeing! This color is perhaps the only red Halpha emission what is bright enough to be detected visually. The inner edges of the wings are also somewhat colored as wine-red or rust-brown. I did not noticed red color of star E and/or orange color south of the Trapezium. I'll give it a try next time. An always astonishing detail in big apertures are the amount of faint stars within the nebula. I think the view through "Barbella" must be truly amazing. The difference between the 27-inch and the 36-inch is greater than expected. Faintest star I could detected around the Trapezium was star "H" as a single star. I never saw star "I".

Howard B
January 11th, 2017, 11:27 PM
Hi Uwe,

You're right, I was at the visitor's Center on Mauna Kea when I made the sketch with the 8 inch scope. Actually, I was in the lower parking lot to get away from the all lights at the Visitor's Center - they really should have an observing area up there that's shielded from all the vehicles.

I'm normally not very sensitive to seeing color either, but by accident I tried a technique I'd read about on Cloudy Nights a few years ago. While observing M42 from Steens Mountain in 2014 my iPhone stopped playing music, so went to check what happened, and briefly exposed my dark adapted eyes to the bright screen. When went back to the eyepiece the orange areas I mentioned above were so prominent I could barely believe it! I've tried this technique on purpose a few times since then and it does work - but it works best when the transparency and seeing are both good, as you pointed out.

The central area around the Trapezium is the most complex and difficult astronomical sketching I've tried so far. Getting the proportions correct has been the most important thing for me - my first attempt was a little lopsided and I ran out of room to add details. Once I corrected the proportions it's been a little easier to continue the sketching, but still, there is so much much! It would take me a decade to draw this area with Jimi's 48 inch.

I've seen down to the G star in my 28 inch, but not the H or I stars. I haven't really tried with Jimi's scope because each night I've been there when Orion was well placed the seeing has been too soft.

kisspeter
January 12th, 2017, 09:38 AM
I can contribute only very old and pretty bad drawings. The first one was actually one of my first deep-sky drawings at the age of 13.

2.5", f/7.7 Newtonian, 1995:
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4.3", f/7.3 Newtonian, 1997:
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Just like you I am working on a new drawing (with 4", 1.8° field) and it will hopefully be much better than my previous ones.

John Herschel's drawing is amazing. I knew it before and I hope I will be able to do something similar one day.

I haven't seen features 1-4 mentioned by Howard (using a 16" Dob). I will check them next time but don't expect too much. I am not very good at seeing colors in the eyepiece either, especially red.

As another detail I can report that the complete 30' ring is visible with 4 inches under very good conditions.

Paul Alsing
January 12th, 2017, 06:18 PM
... The central area around the Trapezium is the most complex and difficult astronomical sketching I've tried so far. Getting the proportions correct has been the most important thing for me - my first attempt was a little lopsided and I ran out of room to add details. Once I corrected the proportions it's been a little easier to continue the sketching, but still, there is so much much! It would take me a decade to draw this area with Jimi's 48 inch.

I've seen down to the G star in my 28 inch, but not the H or I stars. I haven't really tried with Jimi's scope because each night I've been there when Orion was well placed the seeing has been too soft.

Hi Guys,

My own best view of the Trapezium area was made using the 82" just up the road from Jimi, on November 18th, 2006. Here is what I wrote;

Trapezium, M-42, Orion

"The trapezium is one of the few objects to be viewed both nights. The first night the seeing was just not good enough to see any Trapezium stars other than A-F, but the second night the seeing was nearly perfect, maybe 1/3 arc-second, and then I could easily see G and I within the trapezium and H (but not H') just outside. I had printed a terrific finder chart and photo of the area and could see just about every star in the field. I looked for the proplyd "tails" on the G, H and I stars, but they were just not there, nor was the shock excited [O III] arc near G visible (well, I can dream, can't I?) Almost as an afterthought, after looking only for the difficult objects in the field, I finally noticed the nebulosity! It was exactly like looking down on the clouds from above while in an airplane, puffy clouds as far as the eye can see. What a sight!"

Here is the chart I used...

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Howard, it would probably take you 2 decades to wring out all the details using the 82"...

Jraymond
January 14th, 2017, 03:41 AM
In larger apertures I see "B" as sort of brownish compared to the others. I see "E" as orangish.

The nebula details are too overwhelming.

Howard B
January 14th, 2017, 08:38 PM
Howard, it would probably take you 2 decades to wring out all the details using the 82"...

I agree Paul!! I had a look at the Trapezium area through the 90 inch Bok telescope on Kitt Peak in 2011 and it showed a completely new (to me) level of detail in the nebulosity that I found astonishing. Just inside the area bounded by the A-D stars, the nebulosity had a small-scale texture like a field of sand dunes as seen from above.

Paul Alsing
January 16th, 2017, 03:54 AM
I agree Paul!! I had a look at the Trapezium area through the 90 inch Bok telescope on Kitt Peak in 2011 and it showed a completely new (to me) level of detail in the nebulosity that I found astonishing. Just inside the area bounded by the A-D stars, the nebulosity had a small-scale texture like a field of sand dunes as seen from above.

Exactly! That is just how I felt!

adarshajoisa
February 3rd, 2017, 06:33 AM
The Great Orion Nebula

I've since been working on a drawing of this wonderful nebula with my 28 inch but that will take more time to complete. On the very best nights I've seen a few surprising things and I wonder how many others have noticed:

1. A distinct orange color along the straight edge of the shock front of the Trapezium nebulosity.
2. This same orange color due south of the Trapezium stars, about one Theta Orionis length away.


I managed to observe both of these features a couple of nights ago with my 16", though they looked more reddish/rust colored to me. I hadn't noticed these earlier, and didn't know what I was looking at. Thanks for this!

wvreeven
February 27th, 2017, 09:52 AM
On Saturday night (Feb 25) I observed the trapezium with my 20" at 692x (grrrreat seeing!). E and F appeared orange/brown while A, B, C and D appeared white. I tried for G and H but don't think I have seen them though once I saw something light up at the location of G and once at the location of H. Still I'd call it a negative sighting.

The detail in the central part of M 42 (in and around the trapezium) was overwhelming! And I never noticed so many other stars around the trapezium as that night.


Clear skies, Wouter