M46 w/ NGC 2438
Exposure type:
Roth Ritter
Lamy, NM on 2009, Mar 21
LRGB (180:60:60:60)
RCOS 10RCA @ f/7 (1825mm)
Paramount ME
SBIG STL-11000M, AO-L, Filter set C L R G B

[ click the photo to enlarge ]
Additional Notes:
M46 is an open cluster in the constellation of Puppis and is about 5,500 light-years away with an estimated age on the order of several 100 million years.. The planetary nebula NGC 2438 appears to lie within the cluster near its northern edge, but it is most likely unrelated since it does not share the cluster's radial velocity. [Wikipedia]