[3] Birgitta is a Mars-crossing asteroid, a dynamically unstable group between the main belt and the near-Earth populations, crossing the orbit of Mars.
[2][3] In October 2010, a rotational lightcurve of Birgitta was obtained from photometric observations by American astronomer Brian Skiff.
[a] The result supersedes a previous observation by the discoverer Claes-Ingvar Lagerkvist from the 1970s, which showed a period of 9.02 hours and an amplitude of 0.4 magnitude (U=2).
[6] In December 2014, astronomers at the Palomar Transient Factory in California measured as similar period of 8.97 hours with a brightness variation of 0.32 magnitude (U=2).
[5] According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Birgitta measures 2.67 kilometers in diameter and its surface has a high albedo of 0.304, while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 3.29 kilometers based on an absolute magnitude of 14.78.