|The beautiful planetary nebula NGC 7293 (Helix nebula) in the
constellation Aquarius on August 1 and October 18, 2014. The expanding gas shell ejected from an old red giant star
was discovered in 1824 by German astronomer Karl Ludwig Harding. It is 700 light-years from Earth and one of the
closest planetary nebulae.
Fourty-one 3 minute exposures at ISO 800 with no dark frame subtraction were stacked with Deep Sky Stacker (resulting
in a 2 h 3 min exposure) and further processed in Photoshop. In Switzerland, the Helix nebula doesn't rise more than
23 degrees above the horizon. In addition, dew on the secondary mirror partly ruined several of the 41 frames used
in this image.
|Equipment: Canon EOS 450D Baader modified camera, TeleVue Paracorr Type II coma corrector,
16" f/4.5 "Ninja" dobsonian telescope riding on a dual-axis Tom Osypowski equatorial platform,
Lacerta MGEN autoguider, Lacerta off axis system (field of view comparison:
image of the moon with the same equipment).