Helix nebula (NGC7293), narrowband OIII


Conditions: taken Sep. 21+22, 2003 from a moon-less (but light polluted) sky in Boulder, CO; no wind, no clouds, medium transparency.

Setup: Borg 100ED F6.4, DF-2 focusser, CFW-8 (OIII filter 501/3 nm), ST10XE, MaximDL/CCD, Takahashi EM-10 mount (here's how this setup looks)

Exposure time: 22x900 sec

Processing (Mira6, Mira7, Photoshop7): dark subtracted, flat fielded, masked hot/cold pixels, registered, sigma-reject combined, curves and levels in Photoshop, grain surgery noise reduction, unsharp masking, clipped and resized x0.85

Here's a color image incorporating this data.


Comments greatly appreciated! (mikael@leif.org)