Deep Sky Object in Summer
M54, M69, M70 (Globular Clusters in Sagittarius)


Date & Time: M54: Aug 17 2018, from 21:29 to 21:38 JST(+0900), 3min.×4shots
M69: Aug 17 2018, from 21:44 to 21:53 JST(+0900), 3min.×4shots
M70: Aug 17 2018, from 21:59 to 22:09 JST(+0900), 3min.×4shots
Optical: Meade 25cm(10") Schmidt-Cassegrain with conversion lens (f=1600mm, F6.3)
with BaaderPlanetarium Moon&Skyglow filter
Auto-guided with Meade LX200 Equatorial & Pictor 201XT
Digital Camera: Nikon D810A
Location: Ooizumi, Hokuto city, Yamanashi pref.

Camera Settings: Recording Format...14bit CCD-RAW, converted to 16bit TIFF(4080×4080)
Device Size...20×20mm
Sensitivity...ISO4000, White Balance...Daylight


I'd like to show you three tiny globular clusters distributed around south of the asterism of "Teapot" of Sagittarius in this page. Many globular clusters are distributed surrounding the "Bulge" region of the central Galaxy seems like a convex lens. So the constellation of Sagittarius contains uncountable globular clusters because the center of Galaxy is positioned in the constellation. The Sagittarius occupies only 2% of all area of the celestial sphere, but surprisingly the constellation has about one third of all discovered globular clusters.
These three globulars have diameters of less than 3 arc minutes, you can see only nebula like dimmed images even if you use fairly large telescopes. Perhaps you will realize that M54 is a bit denser than other two.

M54 (NGC6715) / Globular Cluster, type III
R.A.18h 55m 5.9s (2000.0)
Dec.-30° 29' 00" (2000.0)
Apparent Size2.1'
Real Size55 light yrs.
Magnitude7.3
Distance49,000 light yrs.
M69 (NGC6637) / Globular Cluster, type V
R.A.18h 31m 24.0s (2000.0)
Dec.-32° 21' 00" (2000.0)
Apparent Size2.3'
Real Size68 light yrs.
Magnitude8.9
Distance23,000 light yrs.
M70 (NGC6681) / Globular Cluster, type V
R.A.18h 43m 11.9s (2000.0)
Dec.-32° 17' 59" (2000.0)
Apparent Size2.5'
Real Size59 light yrs.
Magnitude9.6
Distance65,000 light yrs.



M28
M55

Copyright(c) 2018 by Naoyuki Kurita, All rights reserved.
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