Object name: M057

Designation(s): M057, IC 1296,

M57 or Ring Nebula: I remember one of the summer nights about 7 months after we opened Hyde Memorial Observatory, a public observatory where I was a supervisor for its first 27 years, we were featuring this nebula. Some fellow had been bitching to me that he couldn\'t understand why we didn\'t allow smoking saying we were as bad as his wife about the subject. Then he looked in the C-14 at this nebula. He yells for his wife to come and take a look. She does and says \"So what?\" He says \"See, God smokes, he blows smoke rings!\" They were still arguing as they left. Actually, it does resemble a ring of smoke in a telescope. We still don\'t allow smoking even on the observing deck.

The nebula is about 2300 light years from us at between the bottom two stars of the Lyra parallelogram. A planetary nebula is formed from the outer layers of a dead star. Its final act is to blow these off leaving only the super hot core (where fusion used to go on in the star). This is usually in the center and very blue since it is blue hot. While the core no longer generates energy it is so massive and so small that it takes billions of years for it to cool. It takes only a few tens of thousands of years for the shell of gas forming the planetary nebula to expand and fade from view. The core that\'s left behind is commonly known as a white dwarf. Such a fate awaits our sun in a bit over 5 billion years from now. You can read more about this at: http://messier.seds.org/m/m057.html

There are two ways this object is normally imaged. One is in a short exposure RGB or LRGB image that picks up only the bright ring and maybe a hint of the material inside the ring. The other is to use narrow band filters to pick up the fainter outer shell. This is normally done in H-alpha light and OIII light. I chose to do neither approach. I didn\'t like the short exposure route and I don\'t have an OIII filter as yet so neither seemed to be what I wanted to do. I\'ve been waiting for seeing good enough to use 0.5\" per pixel resolution. To do that with narrow filters would require maybe 10 hours of exposure time. In three years we\'ve just not had the needed seeing for even 1 hour until a few days ago. I was able to grab one hour of luminosity data before the seeing deteriorated too much. I tried several more nights but seeing just didn\'t cooperate so I went with the one hour I did get. On those nights of lesser seeing, I took color data, 30 minutes per color, at 1\" resolution. The resulting image shows the true color of the outer shell rather than the red color normally seen in narrowband H-alpha dominated images. The OIII light in the blue-green part of the spectrum overcomes the red of H-alpha to give it a rather grey or colorless tone though some pockets of H-alpha can be seen where it dominates.

Also of interest is the spiral galaxy IC 1296. It is very difficult in any scope smaller than 12\" or so. I can just barely see in in the 14\" here so few notice it when looking at the ring. Redshift distance is a bit over 200 million light years so it a rather large two arm spiral. Only very deep images capture the large disk that the arms are embedded in. The many knots of newly formed stars that outline parts of the outer rim of this disk surprised me. I\'d not noticed them before in any image I\'d seen. Though usually deep images are taken using narrowband filters that filter out the light of these star clouds. This galaxy turns out to be extremely interesting in its own right and would likely be far better known and studied if it weren\'t for its much more dramatic \"neighbor\". A quick search of the literature turned up nothing on this guy or its odd star clouds. I need much more exposure time at this seeing to get more detail out of this galaxy.

I cropped this image, the full image is 4 times this size but only contains small fuzzy galaxies same as seen in this cropped image. In fact, I never even processed that part of the data.

A Hubble image (short exposure type) can be seen at:
http://apod.nasa.gov/apod/ap040704.html

How you stretch the more than 4,000 true intensity levels (yes there are actually over 65,000 but they are due to read noise, not real data) in the original image to fit the 256 levels a monitor supports can change the look of an object greatly. It all depends on what detail you wish to show. Thus it is interesting to compare my image to that taken on Kitt Peak (home of far better seeing than I\'ll ever have here in northern Minnesota) with a 20\" telescope (lower image). In his processing, he processed the nebula normally for a short exposure look (upper version). Then he added exposure time and processed it for the faint detail (not shown). It would have been very similar to my image, with the bright parts of the nebula greatly reduced so the fainter outer halo showed. Then, since the short exposure version was done to show the nebula very bright, the two were combined such that the brightest pixel from each image was used to make the final image. Since the nebula was bright in the long exposure image it came though and since the outer parts were only seen in the long exposure version as well as the galaxies they too were in the final image. I wanted to show the detail in the ring normally not seen in the \"standard\" processing of his top image so didn\'t go that route. It does demonstrate how much control the processor has over how the final image looks and what detail you see and don\'t see.
http://www.caelumobservatory.com/obs/m57.html

14\" LX200R @ f/10, L=3x20\' RGB=3x10\'x2, STL-11000XM, Paramount ME