(679648) 2019 XS

(679648) 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]

(679648) 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