| 11. | It has been listed as a member of the open cluster ASCC 123.
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| 12. | "' NGC 381 "'is an open cluster in the Cassiopeia constellation.
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| 13. | Astronomers dubbed the former globular clusters, and the latter open clusters.
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| 14. | "' NGC 6530 "'is an open cluster in the constellation Sagittarius.
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| 15. | Notable features include the open cluster NGC 6025 and planetary nebula NGC 5979.
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| 16. | Berkeley 90 is a smaller open cluster, with a diameter of 5 arcminutes.
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| 17. | The most prominent open cluster in Scutum is the Wild Duck Cluster, M11.
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| 18. | NGC 457 is another open cluster in Cassiopeia, also called the Caldwell 13.
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| 19. | Far dimmer than the other open clusters is NGC 2126 at magnitude 10.2.
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| 20. | Blooms occur in open clusters, up to as many as nine, throughout the season.
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