Object: Constellation: Coordinates: Size: Brightness:
NGC 457 Cas 01h20m / +5817' 20' 6.4mag

The open star cluster NGC 457 ("Owl cluster", "ET cluster") in the constellation Cassiopeia on December 19 / 20, 2015. NGC 457 is 9000 light-years from Earth, measures 30 light-years in diameter and was discovered by the William Herschel 1787. (source: Wikipedia).

Twenty-two exposures of approximately 3 minutes at ISO 400 with no dark frame subtraction were stacked with Deep Sky Stacker (resulting in a 1 h 8 min exposure) and further processed in Photoshop.
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).

Search chart for NGC 457. Map © 2016 "The Mag-7 Star Atlas Project", www.siaris.net. Map is modified. The map can be downloaded here .