As with 22 other asteroids – starting with 913 Otila, and ending with 1144 Oda – Reinmuth selected names from this calendar due to his many asteroid discoveries that he had trouble thinking of proper names. These names are not related to the discoverer's contemporaries. Lutz Schmadel, the author of the Dictionary of Minor Planet Names learned about Reinmuth's source of inspiration from private communications with Dutch astronomer Ingrid van Houten-Groeneveld, who worked as a young astronomer at Heidelberg.[2]
Two tentative lightcurves were obtained by Pierre Antonini in June 2010, and by Robin Esseiva, Nicolas Esseiva and Raoul Behrend in April 2015; both with a period of 14.4±0.5 hours and an amplitude of 0.27±0.05 and 0.25±0.10 magnitude, respectively (U=2-/2-).[13][14] In 2016, a modeled lightcurves using photometric data from various sources, rendered a concurring sidereal period of 14.1163±0.0005 hours and two spin axes of (247.0°, −29.0°) and (86.0°, −63.0°) in ecliptic coordinates.[15]
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Hildrun measures (62.817±0.293), (64.04±1.09) and (66.49±1.7) kilometers in diameter and its surface has an albedo of (0.043±0.007), (0.040±0.001) and (0.0365±0.002), respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0437 and a diameter of 66.59 km based on an absolute magnitude of 9.9.[14] Further published mean-diameters and albedos by the WISE team include (56.81±13.02 km), (60.559±0.798 km) and (64.517±1.054 km) with corresponding albedos of (0.06±0.06), (0.053±0.007) and (0.0387±0.0054).[5][14]
^ abcLightcurve plot of (928) Hildrun, Palmer Divide Observatory, Brian Warner (2004). Rotation period 14.13±0.03 hours with a brightness amplitude of 0.34±0.02 mag. Quality code of 3. Summary figures at the LCDB.
^ abcMasiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
^ abcUsui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
^Hanuš, J.; Ďurech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy & Astrophysics. 586: A108. arXiv:1510.07422. doi:10.1051/0004-6361/201527441.