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M99

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#1 IVM

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Posted 10 May 2014 - 10:32 AM

I can't think of a more dramatic spiral. 16", 225x, remote dark site (SQM 21.64). Old sketch re-worked on a Wacom tablet. Criticism is appreciated.

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#2 Alpha Tauri

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Posted 10 May 2014 - 10:51 AM

Nice extension on the spiral arms. As it gets closer to the core I can definitely pick up subtle layering. Well done :)

#3 niteskystargazer

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Posted 10 May 2014 - 11:51 AM

Ivan,

Very good sketch of M-99 :).

CS,KLU,

:thanx:,

Tom

#4 CarlosEH

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Posted 10 May 2014 - 05:51 PM

Ivan,

An excellent observation/rendering of M99 and it's prominent spiral arms. Are the 'bright clumps" within the spiral arms condensations within them? Thank you for sharing it with us all.

Regards,
Carlos

#5 frank5817

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Posted 10 May 2014 - 06:42 PM

Ivan,

Very fine sketching. Many years ago from my location I could see this galaxy almost as well as your drawing shows. Not anymore. In the early 1980's just 40 minutes south of Chicago this galaxy was great in an 18 inch scope.

Frank :)

#6 IVM

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Posted 10 May 2014 - 07:36 PM

Thank you all for your comments.

Carlos, the bright clumps are condensations, and there are also condensations within condensations. For example, the two longitudinally arranged and especially bright ones inside the large condensation near the end of the massive (western) arm. Some of the photographically prominent HII regions, although small and invisible separately, contribute to the brightness of some of the visible condensations. An example is the pair of HII regions HK (Hodge-Kennicutt) 208 and 210 in the central, elongated bright portion within the southwestern (bottom-right) bright segment in the large arm. On the other hand, not all the visible features are entirely real, structural features within the galaxy: The easternmost (east is to the right) enhancement in the east-ending (smallest) arm is an unresolved pair of a foreground star and the HII region HK 1.

#7 CarlosEH

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Posted 12 May 2014 - 02:35 PM

Ivan,

Thank you for the information on the detail within the spiral arms of this impressive galaxy. I look forward to your future observations.

Regards,
Carlos






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