9641 Demazière

9641 Demazière, provisional designation 1994 PB₃₀, is a stony asteroid from the inner regions of the asteroid belt, approximately 3 kilometers in diameter. It was discovered by Belgian astronomer Eric Elst at ESO's La Silla Observatory site in northern Chile on 12 August 1994.

The stony S-type body is also classified as a V-type or vestoid asteroid. It orbits the Sun at a distance of 2.1–2.8 AU once every 3 years and 10 months (1,403 days). Its orbit has an eccentricity of 0.13 and an inclination of 5° with respect to the ecliptic. The first precovery was obtained at Steward Observatory (Kitt Peak–Spacewatch) in 1991, extending the asteroid's observation arc by 3 years prior to its discovery.

A rotational light-curve was obtained from photometric observations made at the U.S. Palomar Transient Factory, California, in November 2010. It showed a rotation period of 7000991210000000000♠9.9121±0.0527 hours with a brightness amplitude of 0.9 in magnitude (U=2). The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.7 kilometers, based on an absolute magnitude of 15.2.

The minor planet was named in honor of Belgian female scientist Martine De Mazière (b. 1960), director-general at the Belgian Institute for Space Aeronomy as of 2016. Working with the optical scanning of Earth's atmosphere, her research focuses on the effect of aerosols in the atmosphere's composition. Mazière has also assessed the post-Pinatubo NO₂ reduction and recovery, using spectroscopic observations in the UV and visible made at the Swiss Sphinx Observatory (Jungfraujoch) over a period of 10 years. Naming citation was published on 4 May 1999 (M.P.C. 34630).