bessel

< /ˈfri drɪk ˈwɪl hɛlm; German ˈfri drɪx ˈvɪl hɛlm/, 1784–1846, German astronomer.

noun

1. Friedrich Wilhelm (ˈfriːdrɪç ˈvɪlhɛlm). 1784–1846, German astronomer and mathematician. He made the first authenticated measurement of a star’s distance (1841) and systematized a series of mathematical functions used in physics