Deep Sky Object in Winter
NGC2451 & NGC2477 (Open Clusters in Puppis)

Date & Time: Dec 20 2014, from 25:49 to 26:10 JST(+0900)
Composed 4 shots with 6 minutes exposed
Optical: TAKAHASHI 16cm(6.3") epsilon (f=530mm, F3.3)
with IDAS LPS-P1 Light-pollution suppression filter
Auto-guided with TAKAHASHI JP Equatorial & SBIG STV
Digital Camera: Nikon D700
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...12bit CCD-RAW, converted to 16bit TIFF(2784×1848)
Device Size...DX Format (24mm×16mm)
Sensitivity...ISO1600, White Balance...Daylight

NGC2451 / Open Cluster, type d, II 2 m
R.A.07h 45m 24.0s (2000.0)
Dec.-37° 58' 00" (2000.0)
Apparent Size45'
Real SizeN/A
# of Stars40
NGC2477 / Open Cluster, type g, I 2 r
R.A.07h 52m 17.9s (2000.0)
Dec.-38° 33' 00" (2000.0)
Apparent Size27'
Real Size45 light yrs.
# of Stars160
Distance6220 light yrs.
A winter constellation of Puppis in which the Milky Way crosses includes many open clusters. This pair of NGC2451 and NGC2477 lies at the most southern position in the constellation.
A very sparse cluster on the right hand side is NGC2451 and another one fine stars crowded is named NGC2477. NGC2451 contains about 50 member stars in about 45-arc minutes diameter, you can easily enjoy this cluster only with compact binoculars. The cluster has a visual magnitude of 3, so maybe some of member stars can be detected by naked eyes. NGC2477 is found at about 1.5 degrees ESE of NGC2451. You can see the cluster like nebulosity through binoculars, and you need a medium sized telescope to resolve individual stars. NGC2477 has a brightness of about 6th magnitude, it hardly can be seen by your eyes.
The constellation of Puppis has one more pair of open clusters of M46 and M47 in northern region. Both pairs has very different stellar density each other, it may be interesting to compare the impressive contrast of these cluster couples.


The Hyades(Mel.25)

Copyright(c) 2015 by Naoyuki Kurita, All rights reserved.
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