Conditions: aquired at Chaco Natl. Historic Park (New Mexico) and Escalante Natl. Monument (Utah), on May 18 and May 20, 2004. Excellent dark sky sites, no moon, fine weather.
Setup: Borg 100ED F6.4, DF-2 focusser, CFW-8, L(IR reject)+R+G+B filters, ST10XE, MaximDL/CCD, Takahashi EM-10 mount (here's a picture of this setup at Chaco)
Exposure time: L: 11x300 sec (1x1 binning); R,G,B: 3x300 sec (2x2 binning)
Processing (Mira, MaximDL, Registar, Photoshop): dark subtracted, flat fielded, masked hot/cold pixels, de-bloomed with Wodaski's plugin, registered, median/avr combined, DDP, color balanced, slight contrast increase, reduced 50% for web format
I am fascinated by dark nebulae siluetted against stars or bright nebulosity. The snake nebula is a good example of the former and since it is too far south be imaged from my native Denmark it was a good first target for my astro expedition in the American southwest. As usual, I could have integrated for a longer time on all channels, however I also wanted to get more targets than just this one on that trip. To make the picture you see here I started out with 20 light frames, 45 darks, 100 flats and 50 flat-darks; i.e. a grand total of 215 individual frames. Thank goodness not every night is a clear one or I'd never have time to process!
April 30, 2005: The version shown here has been reprocessed as an LLRGB using the technique described by Russell Croman (www.rc-astro.com). Russell
uses DDP instead of excessive curves&levels to reduce the brightness range while taking special care to preserve star colors.
(Click here to see a close-up comparison with my original image. The stars now appear smaller and more colorful.)
Here's my main page where you can see more of the pictures I have taken so far.
Comments greatly appreciated! (mikael@leif.org)
