Wednesday, March 21, 2007

re: M-35/NGC-2158 astroimage


In the last month I've been "gearing up" (almost literally) for having a go at astroimaging. As the British like to say, "There's many a slip between cup and lip." So I've learned.
I'm about ten percent down the road towards the destination: actually winding up with some astroimages of decent quality. The image here is M-35. Click on the image for a full screen view.
To me the most interesting features of this image are (a) the star colors, (b) the "3-D illusion" of the M-35 cluster, and (c) the myriad "dim bulbs" - meaning faint stars that cannot be seen with the naked eye. The hundreds of them that appear on the image remind me of Carl Sagan's "billions and billions and billions of stars!" Indeed. And most of those billions and billions of stars in the Milky Way are dim bulbs. We're very lucky, by the way, that Old Sol is not one of them.
I won't reveal my limited astrophysical knowledge by discussing the importance of star colors. Simply think of a star's color as indicating its temperature. For example, red stars are relatively cool, aging stars like Betelgeuse and Aldebaran. Blue-white stars are often younger, intensely hot, super-giants like Rigel (estimated 55,000x more luminous than Sol, 910LY distant from us). Sirius outshines Rigel, but only because it is so close to us, at 8.65 LY, the fifth closest star (approximately 22x more luminous than Sol).
The flaws in the image of M-35/NGC-2158 are many, not the least of which is a modest amount of star trailing (that is readily apparent at the pixel level). Autoguiding during image acquisition is the obvious solution, but that "next step" has provided several complications to date.
The wonky details "behind" this photo are boring to anyone except fellow astroimagers, so I'll place them in subsequent posts.
Cheers.
Max

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