Astronomy and astrophysics vol:341 issue:2 pages:469-479
During many years, several authors discussed whether NGC 2451 was areal open star cluster or not. By using parallaxes and proper motions from HIPPARCOS satellite, and Geneva multicolour photometric measurements of 64 stars, the existence of two clusters A and B is confirmed. Distances and Geneva colour excesses E[B - V] are respectively 197 pc, 0.01 and 358 pc, 0.12 for NGC 2451 A and B. The two clusters have the same age (log t = 7.7).