Deep Sky Object in Summer
M23 (Open Cluster in Sagittarius)


Date & Time: Aug 7 2010, from 23:18 to 23:34 JST(+0900)
Composed 3 shots with 8 minutes exposed
Optical: TAKAHASHI 16cm(6.3") epsilon (f=530mm, F3.3)
with IDAS LPS-P1 Light-pollution suppression filter
Auto-guided with TAKAHASHI EM-200 Equatorial & Meade Pictor 201XT
Digital Camera: Nikon D50 (Remodeled)
Location: Koumi town., Nagano pref.

Camera Settings: Recording Format...12bit CCD-RAW, converted to 16bit TIFF(3008×2000)
CCD Sensitivity...ISO800




M23 (NGC6494) / Open Cluster, type e, II 2 r
R.A.17h 56m 48.0s (2000.0)
Dec.-19° 01' 00" (2000.0)
Apparent Size25.0'
Real Size33 light yrs.
# of Stars150
Magnitude6.9
Distance4490 light yrs.
M23 is a medium sized open cluster in northern region of Sagittarius. You can find the cluster around a bit mu Sgr side on the midway between xi Oph and mu Sgr. And you can use another way of 5.5 degrees NNW of the Lagoon Nebula (M8).
As this image shows you, there is a star with 6th magnitude just northwest of the cluster, the star can be a good mark to search M23 with finder scopes. The cluster has member stars of very same brightness, and you may be fascinated by the scenic beauty of the cluster like twinkling grains of sand scattered in the Milky Way. About 150 fine stars with 12th or 13th magnitudes are gathered.




M18

M25


Copyright(c) 2010 by Naoyuki Kurita, All rights reserved.
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