(878) Mildred

878 Mildred
Discovery [1][2]
Discovered byS. B. Nicholson
H. Shapley
Discovery siteMount Wilson Obs.
Discovery date6 September 1916
(878) Mildred
1916 f, 1985 VG6, 1991 GZ8
main-belt Nysa[3]
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc99.57 yr (36368 days)
Aphelion2.8953 AU (433.13 Gm)
Perihelion1.8286 AU (273.55 Gm)
2.3619 AU (353.34 Gm)
3.63 yr (1325.9 d)
0° 16m 17.472s / day
Physical characteristics
Dimensions~4 km[4]
2.660 h (0.1108 d)[1]

878 Mildred is a minor planet in the main belt orbiting the Sun. It is the lowest numbered, and thus the namesake, of the Mildred family of asteroids, a subgroup of the Nysa family.[3] The Mildred subgroup, and by extension 878 Mildred itself, is thought to have been formed by a recent fragmentation event from a larger asteroid.[3]


878 Mildred was originally discovered in 1916 using the 1.5 m Hale Telescope at the Mount Wilson Observatory, but was subsequently lost until it was again observed on single nights in 1985 and 1991 (a lost asteroid).[2] Initially only two observations of the asteroid were taken on 1916-09-06 which does not allow for an accurate orbital determination, however interest in the object prompted further investigation and more measurements were taken in late September and October.[4] The asteroid was re-discovered in 1991 by Gareth V. Williams.[5] It is named after Mildred Shapley Matthews.

Physical properties[]

By comparing the asteroid's perceived brightness and the then computed distance from the Sun they arrived at an absolute visual magnitude of 14.3, which if one assumes Mars-like albedo gives an approximate diameter of 3 to 5 kilometers.[4]


  1. ^ a b c d "JPL Small-Body Database Browser: 878 Mildred (1916 f)" (2015-04-10 last obs). Retrieved 3 May 2016.
  2. ^ a b IAU Circular: IAUC 5275. Central Bureau for Astronomical Telegrams (Report). IAU. 25 May 1991. Retrieved 20 February 2020.
  3. ^ a b c d Cellino, A.; et al. (August 2001). "The Puzzling Case of the Nysa–Polana Family". Icarus. 152 (2): 225–237. Bibcode:2001Icar..152..225C. doi:10.1006/icar.2001.6634.
  4. ^ a b c Shapley, H.; Nicholson, S. B. (1917). "The Orbit and Probable Size of a Very Faint Asteroid (878) Mildred". Astronomical Journal. 30 (710): 127–128. Bibcode:1917AJ.....30..127S. doi:10.1086/104199.
  5. ^ "MPC staff - Gareth Williams". Minor Planet Center. International Astronomical Union. Retrieved 26 August 2014.

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