FUZZY SPOT, February 2001, Orion (part 2)
Last month we covered many objects in Orion, but there was an obvious omission, the Great Orion Nebula, which is the topic of this months column. Also known as M-42 and NGC 1976, this object is probably the most observed deep sky object, at least in the northern hemisphere (the Pleiades and the Andromeda Galaxy are the only other objects that are in competition), and was the first object I pointed my 10 scope at when I received it.
One of the problems with such a phenomenal and detailed object
is knowing where to start, what to write down, and how not to be
overwhelmed. Here are a few suggestion on how to tackle
this object, which I have found useful:
1) Observe it often and always take a few notes even if its just a sentence or a real quick sketch.
2) Observe it in different conditions. Sometimes a view from the city may show some detail that is overwhelmed when viewed from a dark site.
3) Observe with different equipment. Pay attention to what you see naked eye, in binoculars, in different telescopes, and at different magnifications. Dont be afraid to ask someone at a star party if you can observe this object through their telescope (or any object for that matter) and take some notes. Most people will gladly oblige, although they may ask you to wait till they get to a good breaking point.
4) Plan on spending an evening out just observing this object. I have done this a couple of times and it has been quite rewarding.
5) Focus on a particular portion of the object. Perhaps you noticed a particular wisp or dark spot which you never noticed before.
Before I get into my observations, there are a few names to portions of the nebula which should be defined.
The Trapezium is the central 4 bright stars which are responsible for illuminating the entire nebula. Good optics, good seeing, and good eyes may show 6 or more stars.
The Fish mouth is the dark lane pointing to the Trapezium, entering the nebula from the north. I'm not sure where this name came from as I've never seen anything that looks like a fishes mouth.
The Bat Wings or Wings are the portions of the nebula that flare away from the Trapezium to the east and west.
The Huygenian Region is the brightest central portion of the nebula around the Trapezium and is roughly square shaped.
Naked Eye. There appears to be three stars in a row which are the sword of Orion. Upon careful observation, the central star is obviously fuzzy, especially in dark skies.
10x50 Binoculars. The nebulosity is obvious, but I can't split the trapezium. However the two stars to the E of the trapezium are split. N of trapezium, I can see the fish mouth dark area, the nebulosity at M-43, and suspect nebulosity at 1973/1977 area. To the S, the nebula fans out strongly. The E wing separates into two portion, the W wing blends in with the nebula. The SW portion extends much further than the SE. The Huygenian Region, which is so obviously brighter in telescopes, is only slightly brighter in binoculars. The nice haze texture is seen as slightly bluish. The S star of sword is the brightest, the cluster to the N (NGC 1981) is obvious as a grouping of 10 stars.
10" F4.5, 30X. Nebulosity abounds! M-42 is the most obvious part, M-43 is not all that obvious, NGC 1977 complex is quite obvious, and NGC 1980 around Iota is quite obvious. At this power, the trapezium is barely split. There is a definite green/blue tint to M-42. The contrast at the fish mouth is quite obvious. The E wing is the poorer and splits into two. The nebula slowly fades on the SE end. The W wing is much brighter and larger. It also slowly fades to the N. At 80X, only M-42 and M-43 are in the field. The trapezium is obviously 4 stars. Although the fish mouth is darker than the rest of the area, it has some nebulosity in it. The Huygenian Region is quite bright with many wisps, creating a smoky appearance. There is a particularly dark area on the SE corner of the Huygenian Region. The E wing curves S sharper than the W wing and the darker edge is more pronounced. As you get into the darker S area, streamers seem to radiate away from the trapezium. The comma shape of M-43 is obvious. Finally, at 240X, the field is very tight. I was hoping to see more stars in the trapezium, but I was still only able to see 4. The Huygenian Region fills the full field and is mottled beyond belief! Just into the fish mouth below the trapezium is a glowing stream cutting across. The field moves so rapidly and the scope is unstable enough that viewing at this power is difficult.
20" F5, 60X. At this power, the entire nebula just fits in the field of view. Perhaps the most noticeable difference from the 10" scope is some additional nebulosity on the S end. The dark spot on the SE edge of the Huygenian Region is very prominent. The fish mouth is much darker in the middle with some nebulosity all around it. M-43 and M-42 are connected by faint nebulosity. The trapezium is easily split 4 way and of course, many more stars are visible. There appears to be a dark "hole" around the trapezium. At 180X, the detail is amazing. Panning around shows stream and puffs of smoke all over the place. The trapezium shows an obvious 5 and sometimes 6 stars. The "hole" around the trapezium is much more filled in with lots of streamers and filaments. The entire Huygenian Region is just full of blue/gray streams with many dark areas. Much nebulosity continues NE away from M-42 and M-43 leaving a dark void for the fish mouth. The wing to the E has much detail at the edges passing between 2 stars. This arm reminds me much of the Veil Nebula.