Tycho Brahe didn't discover a specific object near the Cassiopeia constellation. He is most famous for his precise astronomical observations, which were critical for later scientists like Johannes Kepler.

However, while observing the constellation Cassiopeia, Brahe did discover a supernova in 1572. This event, now known as Tycho's supernova, was a pivotal moment in his career and challenged existing astronomical theories.

So, while he didn't discover an object specifically near Cassiopeia, his observations of the constellation led to the discovery of a significant astronomical phenomenon, the supernova of 1572.