144 Vibilia has been observed to occult a star eleven times between 1993 and 2018. Eight of these events yielded two or more chords across the asteroid."Occult v4.5.5". Archived from the original on 26 December 2018. Retrieved 15 September 2018.
13-cm radar observations of this asteroid from the Arecibo Observatory between 1980 and 1985 were used to produce a diameter estimate of 131 km.[20] Carry gives a diameter of 141.34 kilometers.[7] According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Vibilia measures between 131.36 and 142.38 kilometers in diameter and its surface has an albedo between 0.05 0.06.[5][6][9][8] The Collaborative Asteroid Lightcurve Link (CALL) adopts the results obtained by IRAS, that is, an albedo of 0.0597 and a diameter of 142.38 kilometers. CALL uses an absolute magnitude of 7.92.[15]
Based upon radar data, the near surface solid density of Vibilia is 2.4 g cm−3. The density had been calibrated against that of 433 Eros; the uncalibrated figure is 3.2 g/cm3.[10] Carry gives a density of 3.58±0.84 g/cm3 with a low porosity.[7]
Several well-defined rotational lightcurves of Vibilia have been obtained from photometric observations since the 1980s. Lightcurve analysis gave a rotation period between 13.810 and 13.88 hours with a brightness amplitude between 0.13 and 0.20 magnitude (U=3/3/3/3).[11][12][13] In 2016, an international study modeled a lightcurve from various photometric data sources. It gave a period of 13.82516 hours. The team also determined two spin axis of (248.0°, 56.0°) and (54.0°, 48.0°) in ecliptic coordinates (λ, β) (U/Q=n.a.).[14]
^ abBroz, M.; Morbidelli, A.; Bottke, W. F.; Rozehnal, J.; Vokrouhlický, D.; Nesvorný, D. (March 2013). "Constraining the cometary flux through the asteroid belt during the late heavy bombardment". Astronomy and Astrophysics. 551: 16. arXiv:1301.6221. Bibcode:2013A&A...551A.117B. doi:10.1051/0004-6361/201219296.
^ abHanus, J.; Durech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441.