Object: NGC 1857

Magnitude A / B / C
Separation A-BC/ AC
Position angle A-BC / AC
Spectral class A / B / C
Colour A / B / C
: Auriga
: 05 20.1 / +39 21
: 6
: 7.0
: 40
: 7.8
: 1900
Detail sketch:
Date / Time
Observing Location
Seeing / Transparency
Magnification / Field of View '
: 29/12/08 / 22.15
: Landgraaf
: 3/3
: Orion Optics UK 300mm
: 12mm Nagler Type 4
: 133 / 37
NGC 1857

Observing Report

This cluster was invisible in the 35mm Panoptic. With the 22mm I suspected a sort of star cluster, but it really got visible in the 17mm Nagler. Not an easy cluster to detect with low magnifications, when observing from the suburbs. The 12mm Nagler produced the optimum magnification for this small open cluster. It is very poor (25-30 stars), very compact (only 6' in diameter), but has a beautiful deep yellow-orange lucida at the centre. Beside this bright star I can detect one other significant star, a bright white speck of light to the north-west of the centre of NGC 1857.

There are several long chains in the cluster especially to the south and southwest. Between the chains are vast empty spaces. I can detect no nebulosity or background glow of unresolved stars. There is a large range of brightness, mainly due to the bright yellow-orange central star and the many fine pinpoints at the edge of direct visibility.


The yellow-orange star at the heart of the cluster is a K5III (yellow) giant star with a surface temperature of 2700K.