Sunday, August 28, 2011

Sunspots in white light ~ 28 August, 2011

Recently I acquired a longer focal length achromat, an Astro-telescopes 102mm f/11 refractor.  It is a fairly inexpensive telescope given the quality of the objective lens and I intend to write up a review of it soon. While I have not yet used it enough to complete a quality write up, I did want to evaluate it during white light observation of the Sun.   To observe the Sun in white light I use a Lunt Solar Systems Herschel Prism, along with a zoom eyepiece and a polarizing filter that allows me to quickly zoom in and out on individual spots, facula and granulation as the seeing permits.  Below are a couple of photographs of the telescope mounted in my observatory this morning.

While a longer review of the scope will follow soon enough (forecast for tonight is CLEAR!!), I was extremely happy with the performance of this telescope.  The view of the sun is slightly off-white as compared to my TEC 140mm APO, however, the chromatic aberration (de-focused purple light) that I have noticed at night was much less obvious in this solar configuration.  Perhaps it was the steady atmosphere, perhaps it has something to with the solar prism and polarizing filter- either way the view was exquisite.  This scope will likely become my main instrument for white light observation of the sun.  It provides almost as much detail as the TEC 140, yet it is much lighter and there is something comforting about not having the TEC pointing at the sun for extended periods of time.

Click to enlarge
The sketch at left was completed this morning at 1527 UT, under steady skies.  There was a slight amount of high level cirrus that may have lent itself to the impressive image.  You can see that spot region 11279 contains two very dark spots and three small spots surrounded by a large penumbra.  Just outside this group to the east are 4 small spots.  Region 11277 contains two large spots within an oval penumbra.  Spot region 11275 near the Sun's meridian contains 4 very small spots.  In addition to the numbered regions, there is a large group of spots that have rotated into view on the southeast limb.  This region has extensive facula that can bee seen within the limb darkening.  Similarly, there is some bright facula on the northwest limb where region 11271 is rotating out of view.

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