This is a (partial) list of things named for Friedrich Wilhelm Bessel, a 19th-century German scholar who worked in astronomy, geodesy and mathematical sciences:
Astronomy, geodesy, astronomical bodies 1552 Bessel Bessel's star; see 61 Cygni Bessel (crater) Bessel ellipsoid Besselian elements Besselian epoch Bessel points Repsoid–Bessel pendulum
Mathematics Bessel's correction Bessel's differential equation Bessel's inequality Bessel potential Bessel potential spaces Bessel process
Bessel and related functions Bessel beam Bessel filter Bessel function Bessel–Maitland function Incomplete Bessel functions Bessel polynomial q-Bessel polynomials Bessel series, see Fourier–Bessel series Bessel window Bessel–Clifford function Fourier–Bessel series