641 Agnes

641 Agnes, provisional designation 1907 ZX, is a stony Florian asteroid and slow rotator from the inner regions of the asteroid belt, approximately 9 kilometers (6 mi) in diameter.

641 Agnes
Discovery [1]
Discovered byM. F. Wolf
Discovery siteHeidelberg Obs.
Discovery date8 September 1907
Designations
(641) Agnes
Pronunciation/ˈæɡnɪs/,
German: [ˈaːɡnɛs, ˈaŋnəs][2]
Named after
unknown[3]
1907 ZX · 1952 FD1
main-belt · Flora [4]
Orbital characteristics [1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc109.38 yr (39,951 days)
Aphelion2.5055 AU
Perihelion1.9346 AU
2.2200 AU
Eccentricity0.1286
3.31 yr (1,208 days)
335.75°
0° 17m 52.8s / day
Inclination1.7119°
41.020°
17.704°
Physical characteristics
Dimensions8.26±1.42 km[5]
8.81 km (calculated)[4]
9±2 km[6]
9.24±0.64 km[7]
9.446±0.166 km[8]
9.74±2.66 km[9]
8.9 h[10]
178.0±0.1 h[6]
0.20±0.07[4][6]
0.21±0.15[9]
0.217±0.043[8]
0.299±0.044[7]
0.30±0.11[5]
V–R = 0.500±0.050[6]
S [4][11]
12.10[7] · 12.40[5][8] · 12.5[1] · 12.61[9] · 12.64±0.05[4][6] · 12.72±0.16[11]

    It was discovered on 8 September 1907, by German astronomer Max Wolf at Heidelberg Observatory in southern Germany.[12] The meaning of the asteroids's name is unknown.[3]

    Classification and orbit

    Agnes is a stony S-type asteroid and a member of the Flora family, one of the largest groups of stony asteroids in the asteroid belt. It orbits the Sun in the inner main-belt at a distance of 1.9–2.5 AU once every 3 years and 4 months (1,208 days). Its orbit has an eccentricity of 0.13 and an inclination of 2° with respect to the ecliptic.[1] The body's observation arc begins with a recovered observation at Vienna Observatory, one month after its official discovery observation at Heidelberg.[12]

    Physical characteristics

    Rotation period

    In March 1975, photometric observations by Swedish astronomer Claes-Ingvar Lagerkvist measured a period of 8.9 hours for Agnes. The lightcurve, however, was fragmentary and the result uncertain (U=1).[4][10]

    In October 2013, the first reliable rotational lightcurve of Agnes was obtained by astronomers Frederick Pilcher, Lorenzo Franco and Luis Martinez at Organ Mesa (G50) and Balzaretto Observatory (A81) respectively. Lightcurve analysis gave a well-defined rotation period of 178.0 hours with a brightness variation of 0.55 magnitude (U=3). The team also assumed a standard albedo for stony S-type asteroids of 0.20, calculated an absolute magnitude of 12.64, estimated a mean diameter of 9±2 kilometers, and measured a V–R color index of 0.50.[6]

    With such a long rotation period, Agnes is a slow rotator, of which a few hundred minor planets are currently known.

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Agnes measures between 8.26 and 9.74 kilometers (5.13 and 6.05 mi) in diameter, and its surface has an albedo between 0.21 and 0.30.[5][7][8][9] The Collaborative Asteroid Lightcurve Link adopts the results obtained by Pilcher,[6] and calculates a diameter of 8.81 kilometers.[4]

    Naming

    Any reference of this minor planet's name to a person or occurrence is unknown.[3]

    Unknown meaning

    Among the many thousands of named minor planets, Agnes is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[13]

    References
    1. "JPL Small-Body Database Browser: 641 Agnes (1907 ZX)" (2017-01-27 last obs.). Jet Propulsion Laboratory. Retrieved 7 April 2017.
    2. (German Names)
    3. Schmadel, Lutz D. (2007). "(641) Agnes". Dictionary of Minor Planet Names – (641) Agnes. Springer Berlin Heidelberg. p. 64. doi:10.1007/978-3-540-29925-7_642. ISBN 978-3-540-00238-3.
    4. "LCDB Data for (641) Agnes". Asteroid Lightcurve Database (LCDB). Retrieved 7 April 2017.
    5. Nugent, 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. S2CID 9341381. Retrieved 7 April 2017.
    6. Pilcher, Frederick; Franco, Lorenzo; Martinez, Luis (April 2014). "Rotation Period and H-G Parameters of 641 Agnes". The Minor Planet Bulletin. 41 (2): 71–72. Bibcode:2014MPBu...41...71P. ISSN 1052-8091. Retrieved 7 April 2017.
    7. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
    8. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. S2CID 46350317. Retrieved 7 April 2017.
    9. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. S2CID 119289027. Retrieved 7 April 2017.
    10. Lagerkvist, C.-I. (March 1978). "Photographic photometry of 110 main-belt asteroids". Astronomy and Astrophysics Supplement Series. 31: 361–381. Bibcode:1978A&AS...31..361L. Retrieved 7 April 2017.
    11. 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. S2CID 53493339. Retrieved 7 April 2017.
    12. "641 Agnes (1907 ZX)". Minor Planet Center. Retrieved 7 April 2017.
    13. 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. ISBN 978-3-540-00238-3.

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