Sunday, June 17, 2012

Pits and Spots

I recently joined Mansfield & Sutton Astronomical Society, and the other month I helped out with a solar observing outreach event at Pleasley Pit - an old coal mine that has been lovingly restored and open for visitors to see what life was like down the pit as well as supporting a nature reserve on its surrounding land. The pit is sited on top of a hill, so there were fantastic views to the south towards the distant wind turbines east of Mansfield as well as perfect conditions for solar observing. 

Because of the weather the turnout was really good - one 9 year old girl kept coming back again and again for "just one more look" at the sun - she told me how she had build solar system mobiles and demonstrated the seasons on Earth using a pencil-pierced paper plate in class at school. Kids are some of the most rewarding and challenging people to engage at outreach projects as they either know more than you, or ask questions that seem so simple and common-place on the surface, yet never so simple to answer. "How close to the sun could you go before you caught fire". Hopefully some of her enthusiasm will stay with her into later life.

Views were had in both white light and through a 50mm H-Alpha Solarscope telescope - the latter providing incredible arcing prominences, filaments, and a generally rather active sun. Spurned on by the morning events, I finished off building my own white light filter out of a sheet of Baarder solar film, packet of Shreddies, and obligatory Duck Tape. Once fitted to my trusty ED80 with my new Canon 7D I managed to focus and grab a few dozen frames before the little 'un decided he'd had enough of me taking more interest of a few bits of metal and glass than him, and started to cause mischief of one sort or another.

This is the result of 25 frames from the ED80 and prime focus 7D combination - ISO100@1/640s.

I'm quite impressed with the results really considering it's only a stack of 25 images - the 7D has managed to pick up the granulation on the surface pretty well as well as lighter filamentous areas of disturbance best seen on the limb past the far right large spot and similarly on the left limb too. No idea what these are called though! You also get the darkening limb effect caused by the fact that you are looking through more of the solar "atmosphere" than the point in the centre of the disk.

The sunspots have come out really well though - the four Active Regions groups (AR's) are (from left to right), AR's 1492, 1490, 1488, and 1486 - AR1490 harbouring a C-Class solar flare (a low to medium strength class eruption of charged particles from the solar surface).

The image was aligned, stacked, and initially processed in Iris, then final tweaks, balancing, and framing in Photoshop. The colour is "as shot" - I was going to colourise it, but could not decide which hue of orange to use without it looking somewhat "odd".


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