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Solar Analemma. This outstanding image from Alexandra Hart taken over a period of 4 years charts the midday position of the sun in the sky throughout the year. The north–south component of the analemma results from the change in the Sun's declination due to the tilt of Earth's axis of rotation. The east–west component results from the nonuniform rate of change of the Sun's right ascension, governed by combined effects of Earth's axial tilt and orbital eccentricity.

Merry Christmas, Happy New Year and looking forward to a great solar cycle 25!

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Moving forward from solar cycle 24 to 25

Search found 2 matches

by moshc
Sat Jul 20, 2019 3:32 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: New Quark
Replies: 3
Views: 503

Re: New Quark

Hi George, Great report thanks for sharing! Do you think this replacement Quark is much better than the older one in bandwidth or was it mostly the seeing? Do you think the contrast is closer to a single stack view or a DS view? I think I have a pretty good Quark (I agree, amazing instrument) and wo...
by moshc
Sat Jun 08, 2019 8:15 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Recent Coronado SM90 quality & how much does a SM90 weigh?
Replies: 1
Views: 499

Recent Coronado SM90 quality & how much does a SM90 weigh?

Does anyone have any experience with the quality of recent Coronado SM90 filters? I'm considering getting into a double stack SM90 at some point in the future for my scope and would be helpful to know of what to watch out for in recent production. Also can someone let me know how much one SM90 weigh...