This image of the Sun was taken with a hydrogen-alpha telescope at the Phoebe Waterman Haas Public Observatory at the Museum in DC at 12:12 pm EDT on April 26, 2013.
This was our last view of a giant and interesting sunspot group (visible at right, and called AR 1726) before it rotated off the edge of the Sun. It rapidly grew from nothing only a week before. Our first view of AR 1726 showed an active sunspot group in the center of the Sun. Over the next few days, we took more images of the interesting sunspot group.
While AR 1726 harbored the energy to produce powerful solar flares, it never did. The day after this image, astronomer Harald Paleske captured a final, edge-on view of AR 1726 before it rotated completely out of view.
Telescope: Lunt 100mm hydrogen-alpha
Camera: Lumenera SKYnyx 2-2M