M46 Open Cluster and NGC 2438 Planetary Nebula in Puppis
M46 Open Cluster and NGC 2438 Planetary Nebula in Puppis
M46 Open Cluster and NGC 2438 Planetary Nebula in Puppis
M46 is a bright open cluster in the constellation of Puppis. While the cluster is a worthy object on its own, the superposition of the bright planetary nebula NGC 2438 adds to the beauty of the field. As it happens, the planetary nebula is almost certainly not associated with the cluster since the planetary nebula stage of a star's life is a very late stage. However, the stars in M46 are all very young stars, so the cluster would probably not be old enough to have a member reach its planetary stage. Moreover, the cluster and the planetary nebula have different radial velocities which implies that they are not directly associated.

In this image, North is Up. This image is cropped to 88% of the original full frame.

Exposure Details
Lens Celestron C-8 SCT at Prime Focus
Focal Length 2000mm
Focal Ratio f/10
Mount Schaefer GEM - 7 1/2 Byers Gear
Guiding 80mm f/11 guidescope with PHD Guiding
Camera Canon 450D - Gary Honis modified
Exposure 72 subexposures of 180 seconds each at ISO 200 - about 3 1/2 hours total
Calibration 30 darks, 30 flats, 30 bias
Date January 18, 2012
Temperature 45F
SQM Reading
Seeing 2 of 5
Location Pine Mountain Club, California
Software Used Images Plus 4.5 for camera control, Images Plus 4.0 for calibration, stacking, digital development, and multiresolution smoothing. Photoshop CS5 used for flat fielding, levels and curves, color balance, high pass filter, star shrinking, saturation adjustments, and noise reduction. Carboni Tools for additional saturation adjustments and noise reduction.
Notes This is a nice cluster and this image is pretty good. However, the seeing the night I photographed it was quite poor, so the stars are a bit more bloated than I'd like. Oh well, I guess I can't always have the greatest conditions.

This image won 2nd place in Digital Astro's Challenge Photo - Star Cluster category for January 2012.