NGC 1261
globular cluster in the constellation Horologium
NGC 1261 (also known as Caldwell 87) is a globular cluster of stars in the southern constellation of Horologium, first discovered by Scottish astronomer James Dunlop in 1826. The cluster is located at a distance of 53 kilolight-years from the Sun, and 59 kilolight-years from the Galactic Center. It is about 10.24 billion years old with 341,000 times the mass of the Sun. The cluster does not display the normal indications of core collapse, but evidence suggests it may have instead passed through a post core-collapse bounce state within the past two billion years. The central luminosity density is 2.22 L☉·pc−3, which is low for a globular cluster. Despite this, it has a Shapley–Sawyer Concentration Class of II, indicating a dense central concentration.
A total of 22 RR Lyrae variables have been discovered in this cluster, along with two long-period variables, three SX Phoenicis variables, and an eclipsing binary. It was determined to be an Oosterhoff type I cluster, based on the periods of fourteen of the RR Lyrae variables. 18 probable blue straggler candidates have been identified.
The public source identifies “NGC 1261” as globular cluster in the constellation Horologium. This brief keeps that definition visible, then builds a research path around globular, cluster and constellation.
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Named sources, stable identifiers and responsible institutions provide the strongest route from overview to verifiable evidence. The source revision retrieved here is dated Sep 4, 2026. The linked authority identifier is Q59191. None of the 0 selected statements returned an explicit reference. The first chronological checks are 1261 and 1826.
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This entry incorporates text from “NGC 1261” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.