3102 Krok

3102 Krok, provisional designation 1981 QA, is a rare-type asteroid and slow rotator, classified as a near-Earth object of the Amor group, that measures approximately 1.5 kilometers in diameter.

3102 Krok
Discovery [1]
Discovered byL. Brožek
Discovery siteKleť Obs.
Discovery date21 August 1981
Designations
(3102) Krok
Named after
Duke Krok
(legendary Czech figure)[2]
1981 QA
NEO · Amor [1][3]
Orbital characteristics [1]
Epoch 16 February 2017 (JD 2457800.5)
Uncertainty parameter 0
Observation arc35.44 yr (12,944 days)
Aphelion3.1174 AU
Perihelion1.1839 AU
2.1506 AU
Eccentricity0.4495
3.15 yr (1,152 days)
86.843°
0° 18m 45s / day
Inclination8.4439°
172.09°
154.78°
Earth MOID0.1840 AU · 71.7 LD
Physical characteristics
Dimensions1.48 km (derived)[4]
1.6 km[1]
147.8±0.3 h[5]
149.4±1 h[6]
151.8[6]
0.20 (assumed)[4]
QRS (Tholen)[1]
S (SMASS)[1]
Sqw [7] · QRS [4]
B–V = 0.834[1]
U–B = 0.521[1]
16.14±0.2 (R)[6] · 16.2[1] · 16.40±0.15[5] · 16.47±0.35[8] · 16.524±0.15[4][9]

    It was discovered on 21 August 1981, by Slovak astronomer Ladislav Brožek at Kleť Observatory in the Czech Republic.[3] The asteroid was named after Duke Krok a legendary Czech figure.[2]

    Classification and orbit

    Krok orbits the Sun at a distance of 1.2–3.1 AU once every 3 years and 2 months (1,152 days). Its orbit has an eccentricity of 0.45 and an inclination of 8° with respect to the ecliptic.[1] The body's observation arc begins with its official discovery observation at Klet, as no precoveries were taken and no prior identifications were made.[3]

    It has an Earth minimum orbital intersection distance of 0.1840 AU (27,500,000 km), which translates into 71.7 lunar distances.[1]

    Physical characteristics

    In the Tholen classification, Krok is characterized as a rare QRS-type. In the SMASS taxonomy it is classified as a common S-type asteroid, and the "ExploreNEOs" Warm Spitzer program assigns a transitional Sqw-type.[1][7] The R- and Q-types also belong to the larger group of stony asteroids.

    Rotation and shape

    In September 1991, a first rotational lightcurve of Krok was obtained by American astronomer Alan Harris. Lightcurve analysis gave an exceptionally long rotation period of 147.8 hours with a brightness amplitude of 1.0 magnitude, which indicates that the body has a non-spheroidal shape (U=3).[5]

    Between 2000 and 2005, several photometric observations made by Czech astronomer Petr Pravec gave a similar period between 149.4 and 151.8 and an amplitude of 0.7 to 1.3 (U=3/3-).[6] This makes Krok as slow rotator.

    Diameter and albedo

    According to Tom Gehrels' 1994 publication "Hazards due to Comets and Asteroids", Krok measures 1.6 kilometers in diameter based on a generic surface albedo of 0.15,[1] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony S-type asteroids of 0.20 and calculates a diameter of 1.48 kilometers with an absolute magnitude of 16.5.[4]

    Naming

    This minor planet was named after Duke Krok, a legendary figure in Czech history, and the first judge ("duke") of the Slavonic tribes in ancient Bohemia. He was also the father of Princess Libuše, who, together with her husband Přemysl founded the Přemyslid dynasty of Czech royalty.[2] The official naming citation was published on 18 December 1994 (M.P.C. 24410).[10]

    References
    1. "JPL Small-Body Database Browser: 3102 Krok (1981 QA)" (2017-01-28 last obs.). Jet Propulsion Laboratory. Retrieved 25 April 2017.
    2. Schmadel, Lutz D. (2007). "(3102) Krok". Dictionary of Minor Planet Names – (3102) Krok. Springer Berlin Heidelberg. p. 256. doi:10.1007/978-3-540-29925-7_3103. ISBN 978-3-540-00238-3.
    3. "3102 Krok (1981 QA)". Minor Planet Center. Retrieved 25 April 2017.
    4. "LCDB Data for (3102) Krok". Asteroid Lightcurve Database (LCDB). Retrieved 25 April 2017.
    5. Harris, A. W.; Young, J. W.; Dockweiler, Thor; Gibson, J.; Poutanen, M.; Bowell, E. (January 1992). "Asteroid lightcurve observations from 1981". Icarus. 95 (1): 115–147.ResearchsupportedbyLowellObservatoryEndowmentandNASA. Bibcode:1992Icar...95..115H. doi:10.1016/0019-1035(92)90195-D. ISSN 0019-1035. Retrieved 25 April 2017.
    6. Pravec, P.; Harris, A. W.; Scheirich, P.; Kusnirák, P.; Sarounová, L.; Hergenrother, C. W.; et al. (January 2005). "Tumbling asteroids". Icarus. 173 (1): 108–131. Bibcode:2005Icar..173..108P. doi:10.1016/j.icarus.2004.07.021. Retrieved 25 April 2017.
    7. Thomas, Cristina A.; Emery, Joshua P.; Trilling, David E.; Delbó, Marco; Hora, Joseph L.; Mueller, Michael (January 2014). "Physical characterization of Warm Spitzer-observed near-Earth objects". Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. Retrieved 25 April 2017.
    8. 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. Retrieved 25 April 2017.
    9. 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. Retrieved 25 April 2017.
    10. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 25 April 2017.
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