375 Ursula, provisional designation 1893 AL, is a dark asteroid and parent body of the Ursula family from the outer regions of the asteroid belt. It is one of the largest asteroids with a diameter of approximately 200 kilometers. It was discovered on 18 September 1893, by French astronomer Auguste Charlois at Nice Observatory in France.[16] The referent of the asteroids's name is unknown.[2]
In January 2017, the so-far best-rated rotational lightcurve of Ursula was obtained from photometric observations by American astronomer Frederick Pilcher at the Organ Mesa Observatory (G50), New Mexico. Lightcurve analysis gave a rotation period of 16.899 hours with a brightness amplitude of 0.11 magnitude (U=3).[12]
Observations of an occultation on 15 November 1984, produced six chords indicating an estimated diameter of 216±10 km.[9] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0494 and adopts a diameter of 216.1 kilometers based on an absolute magnitude of 7.21.[3]
Naming
Any reference of this minor planet's name to a person or occurrence is unknown.[2]
^ abcdNugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117.
^Schober, H. J. (December 1982). "Rotations of all asteroids larger than 200 KM". IN: Asteroids: 21–26.ResearchsupportedbytheSteiermaerkischerWissenschafts–undForschungslandesfonds, FondszurFoerderungderWissenschaftlichenForschung. Bibcode:1983acm..proc...21S.
^Schober, H. J. (September 1987). "Rotation and variability of the large C-type asteroid 375 URSULA". Astronomy and Astrophysics. 183 (1): 151–155. Bibcode:1987A&A...183..151S. ISSN0004-6361.
^ abPilcher, Frederick (July 2017). "Rotation Period Determinations for 49 Pales, 96 Aegle, 106 Dione 375 Ursula, and 576 Emanuela". The Minor Planet Bulletin. 44 (3): 249–251. Bibcode:2017MPBu...44..249P. ISSN1052-8091.
^ abHarris, A. W.; Young, J. W.; Bowell, E.; Tholen, D. J. (November 1999). "Asteroid Lightcurve Observations from 1981 to 1983". Icarus. 142 (1): 173–201. Bibcode:1999Icar..142..173H. doi:10.1006/icar.1999.6181.
^Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026.
^Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
^Schmadel, Lutz D. (2007). "Appendix 11 – Minor Planet Names with Unknown Meaning". Dictionary of Minor Planet Names – Fifth Revised and Enlarged revision. Springer Berlin Heidelberg. pp. 927–929. ISBN978-3-540-00238-3.