M46 and M47 - Open Star Clusters in Puppis


Copyright 2004 Hap Griffin

If you look a few degrees to the east or the bright star Sirius from a dark sky location, you will notice two smudges of light in the path of the Milky Way.  Upon closer inspection, two open star clusters, M46 and M47, are revealed.  M46 shown here on the left, is a relatively dense open cluster comprised of some 500 stars, many much more luminescent than our own Sun.  The cluster is calculated to be approximately 300 million years old and lies at a distance of 5400 light years.  The cluster holds a famous planetary nebula...NGC 5438...a somewhat spherical shaped cloud of gas blown from a central star, which can be seen here just to the left of the upper boundary of the cluster.  

M46, here on the right, includes approximately 50 stars and lies at a distance of 1600 light years.  The large difference in the distances of these two clusters indicates that they are not really neighbors, but are only seen as such from our vantage point.

Just below the midpoint of a line drawn between M46 and M47 is a small reddish patch.  This is the very distant and faint (magnitude 30!) open cluster NGC 2425.  Near the top edge of the photo, above M47, is another open cluster, NGC 2423. 


Date/Location:    December 10, 2004     Griffin/Hunter Observatory    Bethune, SC
Instrument:    Canon 300D (modified) Digital SLR through Orion ED80 w/ Meade .63 Focal Reducer piggybacked on LX-200 
Focal Ratio:   Approx. f4.5
Guiding:    Auto through LX-200 w/ SBIG ST-237
Conditions:    Visually clear
Weather:    51 F, breezy
Exposure: 10 minutes @ ISO 800 (10 x 1 min exposures) calibrated with flat frame and Master Dark frame (average of 7 darks)
Filters:    Baader UV/IR block
Processing:    Focused and captured with DSLRFocus.  RAW to TIFF conversion, frame calibrations, alignment, Digital Development, Adaptive Richardson_Lucy deconvolution, scaling and JPEG conversion with ImagesPlus