2019 XS is a small Apollo near-Earth asteroid discovered on 2 December 2019 by the Mount Lemmon Survey in Arizona, United States.[2] It passed 1.493 lunar distances (574,000 km; 357,000 mi) from Earth on 9 November 2021 at 03:48 UTC, after which observations were checked by the International Asteroid Warning Network for timing and astrometric accuracy.[7][8][9] During the close pass, the asteroid trailed across the far Southern Hemisphere to the Northern Hemisphere and reached a peak apparent magnitude of 13. A total of 957 observations were collected by Minor Planet Center as part of the International Asteroid Warning Network's campaign.[10]

2019 XS

Goldstone radar images of 2019 XS taken on 11 November 2021
Discovery [1][2]
Discovered by	MLS
Discovery site	Mt. Lemmon Obs.
Discovery date	2 December 2019
Designations
MPC designation	2019 XS
Alternative designations	C1HDFQ2 [3]
Minor planet category	NEO · Apollo [4]
Orbital characteristics [4]
Epoch 21 January 2022 (JD 2459600.5)
Uncertainty parameter 0
Observation arc	21.68 yr (7,919 days)
Earliest precovery date	4 April 2000
Aphelion	1.332 AU
Perihelion	0.6766 AU
Semi-major axis	1.005 AU
Eccentricity	0.3264
Orbital period (sidereal)	1.01 yr (367.74 days)
Mean anomaly	140.339°
Mean motion	0° 58m 44.218s / day
Inclination	4.447°
Longitude of ascending node	49.483°
Argument of perihelion	250.285°
Earth MOID	0.004003 AU (598,800 km)
Physical characteristics
Mean diameter	~70 m [5]
Synodic rotation period	2.35±0.01 h[6] 3.01±0.01 h[6]
Absolute magnitude (H)	23.96±0.33 [4] 23.87 [1]

2019 XS is well-observed with a long observation arc of over 21 years, enough to distinguish subtle changes in its orbit over time due non-gravitational acceleration by the Yarkovsky effect.[4][10] Highly precise radar observations by NASA's Goldstone Solar System Radar on 11 November 2021 have significantly constrained the asteroid's orbit and 2021 close approach distance to within a few kilometres.[4] Radar imaging has shown that the asteroid is roughly 70 m (230 ft) in diameter, with a rotation period around 3 hours.[5]

Continuous photometric observations by the Center for Solar System Studies in Landers, California show an irregular light curve for 2019 XS, signifying that the asteroid is in a tumbling rotation state.[6] The light curve of 2019 XS appears to display two overlapping periods of 2.35 and 3.01 hours, which could possibly be associated with the asteroid's rotation and precession.[6]

See also

• 2012 TC4, another near-Earth asteroid with a dedicated IAWN timing campaign

References

External links

• 2019 XS: Timing Assessment, International Asteroid Warning Network, 3 October 2021
• Goldstone Radar Observations Planning: Orpheus, 2004 UE, 2019 XS, and 2010 VK139, Lance A. M. Benner, Jet Propulsion Laboratory
• 2019 XS at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemeris · Obs prediction · Orbital info · MOID · Proper elements · Obs info · Close · Physical info · NEOCC
• 2019 XS at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical Properties · Summary
• 2019 XS at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit diagram · Orbital elements · Physical parameters