Conditions: taken Nov. 17+18, 2003 from a moonless (but light polluted sky) in Boulder, CO; some gusty wind, no clouds, medium/low transparency.
Setup: Nikon 180 mm F4, DF-2 focusser, H-alpha filter, ST10XE, MaximDL/CCD, Takahashi EM-10 mount (here's a mechanical description of this setup)
Exposure time: 1x2 mosaic, 13x900 sec on each frame
Processing in Mira6 & Mira7: dark subtracted, flat fielded, masked hot/cold pixels, registered, sigma-reject combined
Processing in Photoshop7: curves and levels, merged images, grain surgery noise reduction, removed blooming, layers and masks, correction of corner gradients. For this web version I had to reduce the image by a factor two to get it to fit on most monitors, which really is a pitty since the original has a stellar FWHM of ~1.3 pixels.
After doing the processing I realized that Grain Surgery should have been applied prior to the mosaic merging since the noise
characteristics differ slighty on the two nights. The gradient removal was also performed in a somewhat mediocre way, as is evident on
the lower corners.
Comments greatly appreciated! (mikael@leif.org)