(164121) 2003 YT1

(164121) 2003 YT₁, provisional designation 2003 YT₁, is a bright asteroid and synchronous binary system on a highly eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 2 kilometers (1.2 miles) in diameter. It was discovered on 18 December 2003, by astronomers with the Catalina Sky Survey at the Catalina Station near Tucson, Arizona, in the United States.^[1] The V-type asteroid has a short rotation period of 2.3 hours.^[12] Its 210-meter sized minor-planet moon was discovered at Arecibo Observatory in May 2004.^[3][4]

(164121) 2003 YT₁

Mosaic of radar images of 2003 YT1 and its moon by Arecibo Observatory on 4 May 2004
Discovery[1]
Discovered by	Catalina Sky Srvy.
Discovery site	Catalina Stn.
Discovery date	18 December 2003
Designations
MPC designation	(164121) 2003 YT1
Alternative designations	2003 YT1
Minor planet category	Apollo · NEO · PHA[1][2]
Orbital characteristics[2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc	35.41 yr (12,934 d)
Aphelion	1.4335 AU
Perihelion	0.7857 AU
Semi-major axis	1.1096 AU
Eccentricity	0.2919
Orbital period (sidereal)	1.17 yr (427 d)
Mean anomaly	11.417°
Mean motion	0° 50m 35.88s / day
Inclination	44.064°
Longitude of ascending node	38.335°
Argument of perihelion	91.042°
Known satellites	1 (D: 210 m; P: 30 h)[3][4]
Earth MOID	0.0027 AU (1.0519 LD)
Physical characteristics
Mean diameter	1.0 km[3] 1.100±0.088 km[5] 1.561±0.202 km[6] 1.717±0.550 km[7]
Synodic rotation period	2.34 h[8] 2.343 h[3] 2.343 h[9] 3.0025±0.0001 h[10]
Geometric albedo	0.198±0.153[7] 0.240±0.067[6] 0.36±0.20[11] 0.486±0.040[11] 0.4861±0.0395[5] 0.5848 (derived)[12]
Spectral type	V[12][13][14]
Absolute magnitude (H)	16.2[2][5][12] 16.20±0.3[7]

Orbit and classification

2003 YT₁ is a member of the Earth-crossing group of Apollo asteroids, the largest group of near-Earth objects with approximately 10 thousand known members.^[1][2]

It orbits the Sun at a distance of 0.8–1.4 AU once every 1 years and 2 months (427 days; semi-major axis of 1.11 AU). Its orbit has an eccentricity of 0.29 and an inclination of 44° with respect to the ecliptic.^[2] The body's observation arc begins with a precovery taken at the Siding Spring Observatory in November 1989, more than 14 years prior to its official discovery observation at Catalina.^[1]

Close approaches and Torino rating

The asteroid has an Earth minimum orbital intersection distance of 0.0027 AU (404,000 km; 251,000 mi), which corresponds to 1.05 lunar distances and makes it a potentially hazardous asteroid due to its sufficiently large size.^[2] On the Torino Scale, this object was rated level 1 on 27 December 2003 with an observation arc of 8.7 days.^[15] It was removed from the risk table on 29 December 2003.^[16] Over the next ten million years the asteroid has a 6% chance of impacting Earth.^[17]

On 30 April 2004 it made a close approach at a nominal distance of 0.073 AU (28 LD), and on 31 October 2016, it passed Earth at 0.035 AU (14 LD). The asteroid's closest encounter with Earth will be on 29 April 2073, when it is projected to pass at 0.0113 AU (4.4 LD) only (see table).^[2]

2003 YT₁ has unique orbital characteristics among minor planets. It is the only known binary asteroid to have an Earth MOID within the Moon's Apogee.^[18]

Earth Approach on 3 November 2023^[2]

Date	JPL Horizons nominal geocentric distance (AU)	uncertainty region (3-sigma)
2023-Nov-03 12:33	0.05936 AU (8.880 million km)[2]	±18 km[19]

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	15.3	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≈0.017 LD). (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

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

• v
• t
• e

Meteor stream

On 28 April 2017, a 2.7 cm (1 in) fragment of 2013 YT₁ is suspected of having impacted Earth creating a fireball over Kyoto, Japan.^[17] The fragment would have broken off the parent body within the last ten thousand years.

Physical characteristics

Animation of Arecibo radar images showing 2003 YT₁'s rotation and its satellite's orbital motion on 3 May 2004

This object has been characterized as a bright Vestian-like V-type asteroid.^[12][14][13]

Rotation period

Several rotational lightcurve of this asteroid have been obtained from photometric observations (U=2/n.a./3/3).^{[8][3][9][10]} Analysis of the best-rated lightcurve gave a short rotation period of 2.343 hours with a brightness amplitude between 0.16 and 0.27 magnitude.^[12]

Diameter and albedo

According to radar observations with the Arecibo Observatory and the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, this asteroid measures between 1.0 and 1.717 kilometers in diameter and its surface has an albedo between 0.198 and 0.4861.^{[3][5][6][7][11]}

The Collaborative Asteroid Lightcurve Link derives an albedo of 0.5848 and adopts a diameter of 1.0 kilometer based on an absolute magnitude of 16.2.^[12]

Satellite

The Arecibo radar observations in May 2004 revealed that 2003 YT₁ is a synchronous binary asteroid.^[3] Follow-up observations confirmed a 210-meter sized minor-planet moon orbiting its primary every 30 hours at a distance of 2.7 km.^[4][9]

Numbering and naming

This minor planet was numbered by the Minor Planet Center on 26 September 2007 (M.P.C. 60686).^[20] As of 2018, it has not been named.^[1]

References

1. "164121 (2003 YT1)". Minor Planet Center. Retrieved 20 April 2018.
2. "JPL Small-Body Database Browser: 164121 (2003 YT1)" (2018-04-18 last obs.). Jet Propulsion Laboratory. Retrieved 20 April 2018.
3. Nolan, M. C.; Howell, E. S.; Hine, A. A. (May 2004). "2003 YT_1". IAU Circ. 8336 (8336): 3. Bibcode:2004IAUC.8336....3N.
4. Johnston, Wm. Robert (20 September 2014). "Asteroids with Satellites Database – (164121) 2003 YT1". Johnston's Archive. Retrieved 20 April 2018.
5. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. S2CID 118700974.
6. Delbo, Marco; Walsh, Kevin; Mueller, Michael; Harris, Alan W.; Howell, Ellen S. (March 2011). "The cool surfaces of binary near-Earth asteroids" (PDF). Icarus. 212 (1): 138–148. Bibcode:2011Icar..212..138D. doi:10.1016/j.icarus.2010.12.011. S2CID 122586509.
7. Mainzer, A.; Grav, T.; Masiero, J.; Bauer, J.; Cutri, R. M.; McMillan, R. S.; et al. (November 2012). "Physical Parameters of Asteroids Estimated from the WISE 3-Band Data and NEOWISE Post-Cryogenic Survey". The Astrophysical Journal Letters. 760 (1): 6. arXiv:1210.0502. Bibcode:2012ApJ...760L..12M. doi:10.1088/2041-8205/760/1/L12. S2CID 41459166.
8. Larson, S. M.; Grauer, A. D.; Beshore, E.; Christensen, E.; Pravec, P.; Kaasalainen, M.; et al. (November 2004). "Physical Characteristics of the Binary PHA 2003 YT1". American Astronomical Society. 36: 1139. Bibcode:2004DPS....36.3207L.
9. Pravec, P.; Scheirich, P.; Kusnirák, P.; Sarounová, L.; Mottola, S.; Hahn, G.; et al. (March 2006). "Photometric survey of binary near-Earth asteroids". Icarus. 181 (1): 63–93. Bibcode:2006Icar..181...63P. doi:10.1016/j.icarus.2005.10.014.
10. Behrend, Raoul. "Asteroids and comets rotation curves – (164121)". Geneva Observatory. Retrieved 21 April 2018.
11. Mainzer, A.; Grav, T.; Bauer, J.; Masiero, J.; McMillan, R. S.; Cutri, R. M.; et al. (December 2011). "NEOWISE Observations of Near-Earth Objects: Preliminary Results". The Astrophysical Journal. 743 (2): 17. arXiv:1109.6400. Bibcode:2011ApJ...743..156M. doi:10.1088/0004-637X/743/2/156. S2CID 239991.
12. "LCDB Data for (164121)". Asteroid Lightcurve Database (LCDB). Retrieved 20 April 2018.
13. Sanchez, Juan A.; Michelsen, René; Reddy, Vishnu; Nathues, Andreas (July 2013). "Surface composition and taxonomic classification of a group of near-Earth and Mars-crossing asteroids". Icarus. 225 (1): 131–140. arXiv:1302.4449. Bibcode:2013Icar..225..131S. doi:10.1016/j.icarus.2013.02.036. S2CID 119207812.
14. 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. S2CID 119278697.
15. "Major News about Minor Objects (2003 YT1)". hohmanntransfer. 27 December 2003. Retrieved 20 April 2018.
16. "NEOs Removed from Impact Risks Tables". Near Earth Object Program. NASA. Archived from the original on 2 June 2002. Retrieved 20 April 2018.
17. Kasuga, Toshihiro; Sato, Mikiya; Ueda, Masayoshi (2020). "A Fireball and Potentially Hazardous Binary Near-Earth Asteroid (164121) 2003 YT1". The Astronomical Journal. 159 (2): 47. arXiv:1910.06527. Bibcode:2020AJ....159...47K. doi:10.3847/1538-3881/ab4e1b. S2CID 204576074.
18. NASA.gov
19. "Horizons Batch for 2023-11-03 Close Approach". JPL Horizons. Archived from the original on 29 October 2022. Retrieved 29 October 2022. RNG_3sigma = uncertainty range in km. (JPL#162/Soln.date: 2022-Oct-10 generates RNG_3sigma = 18 km)
20. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 20 April 2018.

External links

• 2003 YT1, IAUC 8336, 6 May 2004
• List of the Potentially Hazardous Asteroids (PHAs), Minor Planet Center
• Asteroids with Satellites, Robert Johnston, johnstonsarchive.net
• PHA Close Approaches To The Earth, Minor Planet Center
• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• (164121) 2003 YT1 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• (164121) 2003 YT1 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• (164121) 2003 YT1 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters