Solar Active Areas 10/20/2013

Here are some images taken with the ASI120MM yesterday. They are probably the best solar images I have ever taken, but they are marred by Newton's Rings--the dark banding on the images, which can be a problem when using monochrome imagers with narrowband filters (in this case, a PST-DS). Some internet posts on the subject suggest the problem is due to the use of a barlow lens, but I have found that the bands are there even without the barlow. Ironically, these bands are more of a problem for high-quality imagers than for lower-tolerance devices. There are a number of potential ways to remove them and I am exploring these options.