# 1999 OJ4

Discovery Orbit of 1999 OJ4 Mauna Kea Observatory July 18, 1999 Epoch 13 January 2016 (JD 2457400.5) Uncertainty parameter 3 3363 days (9.21 yr) 38.8091477 AU (5.80576586 Tm) 36.9475497 AU (5.52727476 Tm) 37.8783487 AU (5.66652031 Tm) 0.024573378 233.13 yr (85150.1 d) 274.652461° 0° 0m 15.22s /day 4.00493625° 127.539040° 300.759535° 1 35.9627 AU (5.37994 Tm) 31.8742 AU (4.76831 Tm) 75 km (47 mi) 0.21 (geometric)[1][4] 43 K (-230°C) 7.1[2]

1999 OJ4 is a fairly small cubewano that orbits in a nearly circular orbit. It is orbited by S/2005 (1999 OJ4) 1, a moon just 3 kilometres smaller than 1999 OJ4 itself.[1]

## Orbit and Relationship with the Kuiper Belt

1999 OJ4 orbit characterizes it as a classical Kuiper Belt object, or cubewano. Due to its nearly circular orbit and low inclination, it is also in the "cold" population of cubewanos. As a result, it is likely reddish in color.[5][6]

## Moon

1999 OJ4 has one moon, S/2005 (1999 OJ4) 1. This moon was discovered by the Hubble Space Telescope[4] on October 5, 2013.[1] It orbits 3,267 kilometres away from 1999 OJ4, completing one orbit every 84.115 days.[1][4] At 72 km, it is nearly the same size as 1999 OJ4. From the surface of 1999 OJ4, S/2005 (1999 OJ4) 1 would have an apparent diameter of roughly 8.11°,[a] over fourteen times the apparent size of the Sun from Earth.

## Notes

1. ^ Calculated by solving ${\displaystyle \scriptstyle {\mathrm {tan} \left({\frac {\theta }{2}}\right)={\frac {\mathrm {radius~of~moon} }{\mathrm {distance~from~surface~of~asteroid~to~center~of~moon} }}}}$.

## References

1. Johnston, W. R. (28 December 2008). "1999 OJ4". Johnston's Archive. Retrieved 2013-10-14.
2. ^ a b "(1999 OJ4) orbit diagram". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 3031899. Retrieved 29 March 2016.
3. ^ "1999 OJ4". Lowell. 26 March 2013. Retrieved 2013-10-14.
4. ^ a b c Grundy, W. M.; et al. (2009). "Mutual Orbits and Masses of Six Transneptunian Binaries". Icarus. arXiv:. Bibcode:2009Icar..200..627G. doi:10.1016/j.icarus.2008.12.008.
5. ^ A. Doressoundiram; N. Peixinho; C. de Bergh; S. Fornasier; P. Thebault; M. A. Barucci; et al. (October 2002). "The Color Distribution in the Edgeworth-Kuiper Belt". The Astronomical Journal. 124 (4): 2279. arXiv:. Bibcode:2002AJ....124.2279D. doi:10.1086/342447.
6. ^ Nuno Peixinho; Pedro Lacerda & David Jewitt (August 2008). "Color-inclination relation of the classical Kuiper belt objects". The Astronomical Journal. 136 (5): 1837. arXiv:. Bibcode:2008AJ....136.1837P. doi:10.1088/0004-6256/136/5/1837.