Photometric observations of Vesta were made at the Harvard College Observatory in 1880–1882 and at the Observatoire de Toulouse in 1909.
These and other observations allowed the rotation rate of Vesta to be determined by the 1950s.
However, the early estimates of the rotation rate came into question because the light curve included variations in both shape and albedo.

Early estimates of the diameter of Vesta ranged from 383 (in 1825) to 444 km.
E.C. Pickering produced an estimated diameter of 513±17 km in 1879, which is close to the modern value for the mean diameter, but the subsequent estimates ranged from a low of 390 km up to a high of 602 km during the next century.
The measured estimates were based on photometry.
In 1989, speckle interferometry was used to measure a dimension that varied between 498 and 548 km during the rotational period.
In 1991, an occultation of the star SAO 93228 by Vesta was observed from multiple locations in the eastern United States and Canada.
Based on observations from 14 different sites, the best fit to the data was an elliptical profile with dimensions of about 550 km × 462 km.
Dawn confirmed this measurement.

Vesta became the first asteroid to have its mass determined.
Every 18 years, the asteroid 197 Arete approaches within 0.04 AU of Vesta.
In 1966, based upon observations of Vesta's gravitational perturbations of Arete, Hans G. Hertz estimated the mass of Vesta as (1.20±0.08)×10⁻¹⁰ solar masses.
More refined estimates followed, and in 2001 the perturbations of 17 Thetis were used to estimate the mass of Vesta as (1.31±0.02)×10⁻¹⁰ solar masses.
Photometric observations of Vesta were made at the Harvard College Observatory in 1880–1882 and at the Observatoire de Toulouse in 1909. These and other observations allowed the rotation rate of Vesta to be determined by the 1950s. However, the early estimates of the rotation rate came into question because the light curve included variations in both shape and albedo.
Early estimates of the diameter of Vesta ranged from 383 (in 1825) to 444 km. E.C. Pickering produced an estimated diameter of 513±17 km in 1879, which is close to the modern value for the mean diameter, but the subsequent estimates ranged from a low of 390 km up to a high of 602 km during the next century. The measured estimates were based on photometry. In 1989, speckle interferometry was used to measure a dimension that varied between 498 and 548 km during the rotational period. In 1991, an occultation of the star SAO 93228 by Vesta was observed from multiple locations in the eastern United States and Canada. Based on observations from 14 different sites, the best fit to the data was an elliptical profile with dimensions of about 550 km × 462 km. Dawn confirmed this measurement.
Vesta became the first asteroid to have its mass determined. Every 18 years, the asteroid 197 Arete approaches within 0.04 AU of Vesta. In 1966, based upon observations of Vesta's gravitational perturbations of Arete, Hans G. Hertz estimated the mass of Vesta as (1.20±0.08)×10⁻¹⁰ solar masses. More refined estimates followed, and in 2001 the perturbations of 17 Thetis were used to estimate the mass of Vesta as (1.31±0.02)×10⁻¹⁰ solar masses.
4 Vesta