Cygnus constellation in Hydrogen-Alpha spectral line. North America, Pelican, Crescent and other emission nebulae.

2×2 mosaic. Images was taken during 4 nights in March and April 2008 from my balcony (in center of 300k pop. town, Visual magnitude limit ~4m)

20 + 20 + 23 + 20 frames. 5 min expositions (total exposition 7 hours), ISO1600

Canon 350D(a) (baader filter mod)
Nikkor 180/2.8 ED (with Canon EOS adapter)
Astrodon 6nm H-alpha (1.25" filter, fixed on the back of objective via cardboard-tape-glue technology :) )

Apr 07 2008 (finishing date)

This image was selected by NASA, as “Astronomical Picture Of the Day, 2008 April 24”