Dave Weixelman took this amazing shot of the Rosette Nebula with the SV80ST and SV field flattener/reducer. This is an Ha+RGB image. Exposures were 8X900 seconds for H-alpha, and 3 X 420 seconds for each RGB filter. Taken with the Apogee U8300 camera on March 18.
At the center of the Nebula is the cluster NGC 2244, which recently formed there. The cluster has itself created the cavity near the center- radiation pressure and stellar winds from the young stars blowing the gas and dust away.