Deep Sky Object in Summer
M54, M69, M70 (Globular Clusters in Sagittarius)
|Date & Time: ||M54: Jun 2 2001, 25:02 JST(+0900), 60sec. exposed 5shots|
|M69: Jun 2 2001, 24:18 JST(+0900), 60sec. exposed 6shots|
|M70: Jun 2 2001, 24:42 JST(+0900), 60sec. exposed 5shots|
|Optical: ||Meade 25cm(10") Schmidt-Cassegrain, afocal method with LV12mm eyepiece
|Synthesized focal length f=2583mm (equivalent f=15222mm in 35mm film format)|
|Auto-guided with Meade LX200 Equatorial
|Digital Camera: ||CASIO QV2800UX
|Location: ||Ooizumi vil., Yamanashi pref.
|Camera Settings: ||Mode.....1600×1200 FINE|
|Lens.....f=12.4mm (equivalent f=83mm in 35mm film format), Stop: F3.2|
|CCD sensitivity.....ISO160, 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)|
|Real Size||55 light yrs.|
|Distance||49,000 light yrs.||
|M69 (NGC6637) / Globular Cluster, type V|
|R.A.||18h 31m 24.0s (2000.0)|
|Dec.||-32° 21' 00" (2000.0)|
|Real Size||68 light yrs.|
|Distance||23,000 light yrs.||
|M70 (NGC6681) / Globular Cluster, type V|
|R.A.||18h 43m 11.9s (2000.0)|
|Dec.||-32° 17' 59" (2000.0)|
|Real Size||59 light yrs.|
|Distance||65,000 light yrs.|