NGC_1866 is an open star cluster located in the constellation Dorado. It was discovered by the astronomer John Frederick William Herschel in 1834. This cluster is approximately 135,000 light-years away from Earth and is part of the Large Magellanic Cloud, a satellite galaxy of the Milky Way. The cluster contains several young, bright stars and is estimated to be around 1 billion years old. NGC_1866 is notable for its rich population of blue supergiants, which are massive stars that have a short lifespan. Observations of this cluster help astronomers understand stellar evolution and the dynamics of star formation.