Deep Sky Object in Winter
M46 & M47 (Open Clusters in Puppis)

Date & Time: Dec 23 2006, from 27:57 to 28:27 JST(+0900)
Composed 4 shots with 10 min. exposed
Optical: PENTAX 7.5cm(2.9") ED refractor with conversion lens (f=360mm, F4.8)
with IDAS LPS-P1 Light-pollution suppression filter
Auto-guided with TAKAHASHI JP Equatorial
Digital Camera: Nikon D70 (remodeled)
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...12bit CCD-RAW, converted to 16bit TIFF(3008×2000)
CCD Sensitivity...ISO1000

Planetary Nebula NGC2438
seen in M46
This picture shows two open clusters about 13 degrees east of Sirius (alpha CMa), and with an interval of about 1.5 degree between them. East Side one is M46 (NGC2437), and another one is M47 (NGC2422). Scenery of those are extremely contrary, to say, M46 consists of plenty of fine stars, but M47 is the brighter and sparse, includes several fifth magnitude stars.
Distances of M46 and M47 are about 5930 and 3740 light years respectively, they have no relation each other in the Galaxy space, we can appreciate these two in the almost same field by chance.
And a left image shows a tiny planetary nebula of NGC2438 floating in M46 with a diameter of about 68". The nebula is a remnant of star emitting gaseous matter in front of M46.

M46 (NGC2437) / Open Cluster, type f, II 2 r
R.A.07h 41m 47.9s (2000.0)
Dec.-14° 49' 00" (2000.0)
Apparent Size24'
Real Size42 light yrs.
# of Stars100
Distance5930 light yrs.
M47 (NGC2422) / Open Cluster, type d, I 3 m
R.A.07h 36m 36.0s (2000.0)
Dec.-14° 30' 00" (2000.0)
Apparent Size25'
Real Size27 light yrs.
# of Stars30
Distance3740 light yrs.

M45 (The Pleiades)


Copyright(c) 2007 by Naoyuki Kurita, All rights reserved.
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