NGC 2509 is an open cluster in the constellation of Puppis.

It was discovered on 3 December 1783 by William Herschel.

[3] It was described as "bright, pretty rich, slightly compressed" by John Louis Emil Dreyer, the compiler of the New General Catalogue.

Some studies have estimated a distance of about 9,500 light-years (2,900 parsecs) away from the Solar System,[1] while older estimates put it at only 2980 light-years (912 parsecs) away.

[4] The latest analysis based on the parallaxes measured by the Gaia spacecraft confirms that it is a relatively distant object, with a distance between 2500 and 3000 parsecs.