14 September

1926: On 14 September 1926, Johan Ludvig Emil Dreyer died.

Dreyer was a Danish astronomer who compiled the New General Catalogue of Nebulae and Clusters of Stars (NGC) in 1888.

He had become the Director of the Armagh Observatory, Ireland, in 1882. It was financially destitute with no prospect of replacing many of its aging instruments or appointing an assistant.

Instead he spend his time there on a compilation of earlier observations. In the NGC, he listed 7840 objects and in its supplements (1895, 1908) he added a further 5386 objects. It still remains one of the standard reference catalogues.

1712: On 14 September 1712, Giovanni Domenico Cassini died.

He was an Italian-born French astronomer who, among others, discovered the Cassini division, the dark gap between the rings A and B of Saturn. He also discovered four of Saturn's moons and devised a first law on astronomical refraction (which alters the apparent position of a heavenly body near the horizon).

In 1664, he observed shadows of four Galilean satellites on Jupiter and determined the planet's rotation period by studying the bands and spots on its surface. Having determined the period of rotation of Mars (1666), he attempted to make that measurement for Venus. In 1675, he stated that Saturn's ring, believed by Huygens to be a single body, was actually composed of small particles.