Deep Sky Object in Summer
M18 (Open Cluster in Sagittarius)

Date & Time: May 11 2007, from 25:48 to 26:02 JST(+0900)
Composed 4 shots with 4 minutes exposed
Optical: TAKAHASHI 12.5cm(4.9") fluorite refractor (f=1000mm, F8.0)
Auto-guided with VIXEN ATLUX Equatorial & Meade Pictor 201XT
Digital Camera: Fujifilm FinePix S2 Pro
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...12bit CCD-RAW, converted to 16bit TIFF(3024×2016)
CCD Sensitivity...ISO1600, White Balance...Auto

M18 (NGC6613) / Open Cluster, type d, II 3 p n
R.A.18h 19m 54.0s (2000.0)
Dec.-17° 08' 00" (2000.0)
Apparent Size9.0'
Real Size13 light yrs.
# of Stars20
Distance4900 light yrs.
M18 is a small-scaled open cluster buried under the summer's Milky Way around Sagittarius. The cluster is positioned just 1 degree south of the Omega Nebula (M17). And the Star Cloud of Sagittarius shows you a splendid view at still more southern region. It can be said that the cluster is fairly modest deep sky object compared with those vast and beautiful scenic spots in the Milky Way.
Perhaps you may get an impression of M18 as a simple striking part of the Milky Way rather than an open cluster. The cluster has small apparent size of 9 arc minutes or so, normal binoculars might be a bit insufficient to enjoy the object. M18 is floating in the Galaxy about 5000 light years away containing ten or more fine stars.



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