2021 DW1

2021 DW₁ is a small Apollo near-Earth asteroid discovered on 16 February 2021 by the Pan-STARRS 1 survey at Haleakala Observatory, Hawaii.^[2] On 4 March 2021 at 8:59 UTC, it passed 1.48 LD (570,000 km; 350,000 mi) from Earth. During the close approach, it trailed across the Northern Hemisphere sky and brightened up to apparent magnitude of 14.6. Extensive observations of 2021 DW₁ during the encounter revealed that it is an elongated, stony asteroid approximately 30 metres (100 ft) in diameter, with a rapid rotation period of 50 seconds. The asteroid's spin axis is unusually oblique relative to its orbital plane, contrary to predictions from the YORP effect.^[5]

2021 DW₁

Discovery[1][2]
Discovered by	Pan-STARRS 1
Discovery site	Haleakala Obs.
Discovery date	16 February 2021
Designations
MPC designation	2021 DW1
Alternative designations	P11dqY3[3]
Minor planet category	NEO · Apollo[4]
Orbital characteristics[4]
Epoch 1 July 2020 (JD 2459396.5)
Uncertainty parameter 4
Observation arc	27 days
Aphelion	1.662 AU
Perihelion	0.9918 AU
Semi-major axis	1.327 AU
Eccentricity	0.2525
Orbital period (sidereal)	1.53 yr (558.29 days)
Mean anomaly	71.096°
Mean motion	0° 38m 41.367s / day
Inclination	6.878°
Longitude of ascending node	162.489°
Argument of perihelion	10.499°
Earth MOID	0.00414 AU (619,000 km)
Physical characteristics
Mean diameter	30±10 m[5]
Synodic rotation period	0.013760±0.000001 h[5] 49.536±0.004 s
Axial tilt	54°±10° or 123°±10° (to orbit)[5]
Pole ecliptic longitude	57°±10° or 67°±10°[5]
Pole ecliptic latitude	29°±10° or −40°±10°[5]
Geometric albedo	0.23±0.02[5]
Spectral type	Sq[5] g–i=0.79±0.01[5] i–z=0.01±0.02 z–g=0.01±0.02[5]
Apparent magnitude	21.0 (discovery)[2] 14.6 (max)[5]
Absolute magnitude (H)	24.8±0.5[5] · 25.02±0.27[4][1]