(192642) 1999 RD₃₂

(192642) 1999 RD₃₂, provisional designation 1999 RD₃₂, is an eccentric asteroid and suspected contact binary, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 5 kilometers in diameter. It was discovered on 8 September 1999, at a magnitude of 18, by astronomers of the LINEAR program using its 1-meter telescope at the Lincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States.[3][2] The asteroid is likely of carbonaceous composition and has a rotation period of 17.08 hours.[4][lower-alpha 1]

(192642) 1999 RD₃₂

Goldstone radar image showing the two lobes of suspected contact binary 1999 RD32.
Discovery [1][2][3]
Discovered by	LINEAR
Discovery site	Lincoln Lab's ETS
Discovery date	8 September 1999
Designations
MPC designation	(192642) 1999 RD32
Alternative designations	1999 RD32
Minor planet category	Apollo · NEO · PHA [1][3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	21.92 yr (8,007 days)
Aphelion	4.6801 AU
Perihelion	0.6093 AU
Semi-major axis	2.6447 AU
Eccentricity	0.7696
Orbital period	4.30 yr (1,571 days)
Mean anomaly	89.009°
Mean motion	0° 13^m 45.12^s / day
Inclination	6.7914°
Longitude of ascending node	310.04°
Argument of perihelion	299.89°
Earth MOID	0.0495 AU · 19.3 LD
Jupiter MOID	0.6702 AU
Physical characteristics
Mean diameter	1.63 km (calculated–dated)[4] 5 km (est.–radiometric)[5]
Rotation period	17.08±0.03 h[6][lower-alpha 1] 17.1±0.5 h[7]
Geometric albedo	0.04 (est.–radiometric)[5] 0.20 (assumed–dated)[4]
Spectral type	C [4][5][8][9]
Absolute magnitude (H)	16.00[8] · 16.23±0.01[9] · 16.3[1][4]

Description

1999 RD₃₂ orbits the Sun at a distance of 0.6–4.7 AU once every 4 years and 4 months (1,571 days; semi-major axis of 2.64 AU). Its orbit has a high eccentricity of 0.77 and an inclination of 7° with respect to the ecliptic.[1]

The asteroid's observation arc begins with a precovery taken at Palomar Observatory in January 1995.[3] It is known that 1999 RD₃₂ passed 0.0093 AU (1,390,000 km; 860,000 mi) from Earth on 27 August 1969.[10] During the 1969 close approach the asteroid reached about apparent magnitude 8.8.[11] The similarly-sized 4179 Toutatis also reached that brightness in September 2004. It passed less than 0.007 AU (1,000,000 km; 650,000 mi) from asteroid 29 Amphitrite on 17 January 1939.[1]

Arecibo radar observations on 5–6 March 2012 showed that 1999 RD₃₂ is approximately 5 kilometers (3 mi) in diameter[5] and has an estimated albedo of only 0.04.[5] Other sources calculate a smaller diameter of 1.63 kilometers based on a dated assumption, that the object is a stony rather than a carbonaceous asteroid.[4] The two visible lobes suggest that 1999 RD₃₂ is a tight binary asteroid or contact binary.[5] About 10–15% of near-Earth asteroids larger than 200 meters are expected to be contact binary asteroids with two lobes in mutual contact.[12]

Close-approaches to Earth[10]

Date	Distance from Earth
1969-08-27	0.0093 AU (1,390,000 km; 860,000 mi)
2012-03-14	0.1487 AU (22,250,000 km; 13,820,000 mi)
2042-03-11	0.1428 AU (21,360,000 km; 13,270,000 mi)
2046-09-04	0.1071 AU (16,020,000 km; 9,960,000 mi)

History of close approaches of large near-Earth objects since 1908 ^(A)

PHA	Date	Approach distance (lunar dist.)			Abs. mag (H)	Diameter ^(C) (m)	Ref ^(D)
		Nomi- nal^(B)	Mini- mum	Maxi- mum
(33342) 1998 WT24	1908-12-16	3.542	3.537	3.547	17.9	556–1795	data
(458732) 2011 MD5	1918-09-17	0.911	0.909	0.913	17.9	556–1795	data
(7482) 1994 PC1	1933-01-17	2.927	2.927	2.928	16.8	749–1357	data
69230 Hermes	1937-10-30	1.926	1.926	1.927	17.5	668–2158	data
69230 Hermes	1942-04-26	1.651	1.651	1.651	17.5	668–2158	data
(137108) 1999 AN10	1946-08-07	2.432	2.429	2.435	17.9	556–1795	data
(33342) 1998 WT24	1956-12-16	3.523	3.523	3.523	17.9	556–1795	data
(163243) 2002 FB3	1961-04-12	4.903	4.900	4.906	16.4	1669–1695	data
(192642) 1999 RD32	1969-08-27	3.627	3.625	3.630	16.3	1161–3750	data
(143651) 2003 QO104	1981-05-18	2.761	2.760	2.761	16.0	1333–4306	data
2017 CH1	1992-06-05	4.691	3.391	6.037	17.9	556–1795	data
(170086) 2002 XR14	1995-06-24	4.259	4.259	4.260	18.0	531–1714	data
(33342) 1998 WT24	2001-12-16	4.859	4.859	4.859	17.9	556–1795	data
4179 Toutatis	2004-09-29	4.031	4.031	4.031	15.30	2440–2450	data
2014 JO25	2017-04-19	4.573	4.573	4.573	17.8	582–1879	data
(137108) 1999 AN10	2027-08-07	1.014	1.010	1.019	17.9	556–1795	data
(35396) 1997 XF11	2028-10-26	2.417	2.417	2.418	16.9	881–2845	data
(154276) 2002 SY50	2071-10-30	3.415	3.412	3.418	17.6	714–1406	data
(164121) 2003 YT1	2073-04-29	4.409	4.409	4.409	16.2	1167–2267	data
(385343) 2002 LV	2076-08-04	4.184	4.183	4.185	16.6	1011–3266	data
(52768) 1998 OR2	2079-04-16	4.611	4.611	4.612	15.8	1462–4721	data
(33342) 1998 WT24	2099-12-18	4.919	4.919	4.919	17.9	556–1795	data
(85182) 1991 AQ	2130-01-27	4.140	4.139	4.141	17.1	1100	data
314082 Dryope	2186-07-16	3.709	2.996	4.786	17.5	668–2158	data
(137126) 1999 CF9	2192-08-21	4.970	4.967	4.973	18.0	531–1714	data
(290772) 2005 VC	2198-05-05	1.951	1.791	2.134	17.6	638–2061	data
^(A) List includes near-Earth approaches of less than 5 lunar distances (LD) of objects with H brighter than 18. ^(B) Nominal geocentric distance from the Earth's center to the object's center (earth radius≈6400 km). ^(C) Diameter: estimated, theoretical mean-diameter based on H and albedo range between X and Y. ^(D) Reference: data source from the JPL SBDB, with AU converted into LD (1 AU≈390 LD) ^(E) Color codes:   unobserved at close approach   observed during close approach   upcoming approaches

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 13 November 2008.[13] As of 2018, it has not been named.[3]

Notes

1. Lightcurve plot of (192642) 1999 RD32, Palmer Divide Observatory, B. D. Warner (2012): rotation period 17.08±0.03 hours with a brightness amplitude of 0.28±0.02 mag. Summary figures at the LCDB

References

1. "JPL Small-Body Database Browser: 192642 (1999 RD32)" (2016-12-04 last obs.). Jet Propulsion Laboratory. Retrieved 16 January 2018.
2. "MPEC 1999-R32 : 1999 RD32". IAU Minor Planet Center. 1999-09-11. Retrieved 2014-02-28. (J99R32D)
3. "192642 (1999 RD32)". Minor Planet Center. Retrieved 16 January 2018.
4. "LCDB Data for (192642)". Asteroid Lightcurve Database (LCDB). Retrieved 16 January 2018.
5. "(192642) 1999 RD32 Goldstone Radar Observations Planning". NASA/JPL Asteroid Radar Research. 12 March 2012. Retrieved 16 January 2018.
6. Warner, Brian D.; Megna, Ralph (July 2012). "Lightcurve Analysis of NEA (192642) 1999 RD32". The Minor Planet Bulletin. 39 (3): 154. Bibcode:2012MPBu...39..154W. ISSN 1052-8091. Retrieved 16 January 2018.
7. Vaduvescu, O.; Macias, A. Aznar; Tudor, V.; Predatu, M.; Galád, A.; Gajdos, S.; et al. (August 2017). "The EURONEAR Lightcurve Survey of Near Earth Asteroids". Earth. 120 (2): 41–100. Bibcode:2017EM&P..120...41V. doi:10.1007/s11038-017-9506-9. hdl:10316/80202. Retrieved 16 January 2018.
8. Carry, B.; Solano, E.; Eggl, S.; DeMeo, F. E. (April 2016). "Spectral properties of near-Earth and Mars-crossing asteroids using Sloan photometry". Icarus. 268: 340–354. arXiv:1601.02087. Bibcode:2016Icar..268..340C. doi:10.1016/j.icarus.2015.12.047. Retrieved 16 January 2018.
9. 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 16 January 2018.
10. "JPL Close-Approach Data: 192642 (1999 RD32)" (2012-11-03 last obs and observation arc=17.8 years). Retrieved 2014-02-28.
11. "1999RD32 Ephemerides for 25 August 1969 through 31 August 1969". NEODyS (Near Earth Objects – Dynamic Site). Retrieved 2014-02-28.
12. Michael Busch (2012-03-12). "Near-Earth Asteroids and Radar Speckle Tracking" (PDF). Retrieved 2014-02-28.
13. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 24 February 2018.

External links

• Arecibo images from 2012
• Asteroid Lightcurve Database (LCDB), query form (info)
• Dictionary of Minor Planet Names, Google books
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
• (192642) 1999 RD32 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters