June 15 and 16, 2013: Lots of fun on the eastern limb in H-alpha

[michael.h.f.wilkinson]

I managed several peeks at the sun in H-alpha yesterday and today, and loads of stuff was going on. Saturday morning showed several proms I had seen before, but in the afternoon on the northern part of the eastern limb, a really big prom developed. Not only that, but it changed its shape quite dramatically as time progressed, and tuning the etalon through the band showed big differences in shape, from a single tree-like structure on the one end, to a tree plus a strange, rod-like shape running at a shallow angle to the surface. To the south the straight prom I had seen before seemed longer than before.

Today the fireworks continued. I spotted the tree-like structure on the north-east again, and loads of activity was visible on the surface on the eastern side. The long prom to the south-east was still going strong, and had a little brother beside it. On the western side, several smaller proms showed.

Early in the afternoon I spotted a small spike between the two main proms on the east, and the 24mm showed a complex structure beyond the limb: a large detached prom. As the afternoon progressed this seemed to move away a bit. On the south-western limb, a low ridge-like prom stood out (maybe part of a large filament I have been following in its progress over the surface).

The detached prom showed up most easily at low magnification (16.7x with the 24mm), less so with the 12mm (33.3x) and slightly better with the 10mm XW (40x), most likely due to better transmission of that EP.

My two young nephews had a look and found the proms really cool.

Clear skies predicted for tomorrow, so I will take the scope to work again.