2023 DW

2023 DW is a near-Earth asteroid of the Aten group. It is approximately 50 meters (160 feet) in diameter, roughly the size of the asteroid that caused the Tunguska event,[lower-alpha 1] and was discovered by Georges Attard and Alain Maury, from the MAP (Maury/Attard/Parrott) asteroid search program in San Pedro de Atacama on 26 February 2023, when it was 0.07 AU (10 million km) from Earth.[1] On 28 February 2023, with an observation arc of 1.2 days, it was rated 1 on the Torino scale for a virtual impactor on 14 February 2046 at 21:36 UTC.[6] The nominal approach is expected to occur about eight hours before the impact scenario at 14 February 2046 13:15 ± 72 minutes.[3] Between 5–8 March, the asteroid was not observed as it was within 40 degrees of the waxing gibbous moon.[7] On 14 March 2023 the European Space Agency was the first to drop to a Torino scale rating of 0.[8] Sentry dropped to a Torino scale rating of 0 on 16 March 2023.[9] It was completely removed from both risk tables on 20 March 2023.[10]

2023 DW
Discovery[1][2]
Discovered byGeorges Attard and Alain Maury
Discovery siteSan Pedro de Atacama
Discovery date26 February 2023
Designations
2023 DW
3BP2721[2]
Orbital characteristics[3]
Epoch 2023-Feb-25 (JD 2460000.5)
Uncertainty parameter 6
Observation arc20 days
Aphelion1.145 AU (Q)
Perihelion0.495 AU (q)
0.820 AU (a)
Eccentricity0.397 (e)
0.742 years (271 days)
120.0° (M)
Inclination5.81° (i)
326.1° (Ω)
2022-Nov-26
40.4° (ω)
Earth MOID0.0005 AU (75 thousand km)
Venus MOID0.03 AU (4.5 million km)[4]
Jupiter MOID4.3 AU (640 million km)
Physical characteristics
Mean diameter
24.3 (MPC)[4]

    2023 DW currently orbits the Sun once every 271 days.[3] It came to perihelion (closest approach to the Sun) on 26 November 2022, and then approached Earth from the direction of the Sun making closest Earth approach on 18 February 2023 at distance of about 8.7 million km.[3]

    Risk

    With an observation arc of 13 days it peaked at a Palermo scale rating of –1.89[11] with the odds of impact then being about 78 times less than the background hazard level.[lower-alpha 2] It was removed from the risk table on 20 March 2023.

    2023 DW nominal approach for 14 February 2046 21:36 virtual impactor
    Solution Observation
    arc
    (in days)    		 JPL Horizons
    nominal geocentric
    distance (AU)    		 uncertainty
    region
    (3-sigma)    		 Impact
    probability    		 Torino
    scale    		 Palermo
    scale
    (max)
    JPL #2 (2023-Feb-28)2 (38 obs)0.0165 AU (2.47 million km)± 21 million km1:830[12]1–2.28
    JPL #5 (2023-Mar-03)4 (55 obs)0.0181 AU (2.71 million km)± 18 million km1:710[13]1–2.21
    JPL #6 (2023-Mar-04)6 (60 obs)0.0095 AU (1.42 million km)± 13 million km1:5431–2.11
    JPL #7 (2023-Mar-05)6 (62 obs)0.0124 AU (1.86 million km)± 13 million km1:613[14]1–2.16
    JPL #8 (2023-Mar-06)6 (62 obs)0.0123 AU (1.84 million km)± 13 million km1:560[15]1–2.12
    JPL #9 (2023-Mar-11)13 (69 obs)0.0121 AU (1.81 million km)± 8 million km1:420[16]1–1.98
    JPL #10 (2023-Mar-12)13 (77 obs)0.0097 AU (1.45 million km)± 7 million km1:360[11]1–1.89
    JPL #11 (2023-Mar-13)15 (91 obs)0.0186 AU (2.78 million km)± 7 million km1:670[17]1–2.18
    JPL #12 (2023-Mar-14)16 (99 obs)0.0192 AU (2.87 million km)± 7 million km1:770[18]1–2.23
    JPL #13 (2023-Mar-15)17 (104 obs)0.0198 AU (2.96 million km)± 6 million km1:1000[19]1–2.34
    JPL #14 (2023-Mar-16)17 (112 obs)0.0216 AU (3.23 million km)± 5 million km1:3600[9]0–2.90
    JPL #15 (2023-Mar-17)18 (115 obs)0.0214 AU (3.20 million km)± 5 million km1:3400[20]0–2.88
    JPL #16 (2023-Mar-19)20 (118 obs)0.0303 AU (4.53 million km)± 4 million kmN/A[5][lower-alpha 3]N/AN/A
    JPL #17 (2023-Mar-20)21 (123 obs)0.0317 AU (4.74 million km)± 3 million kmN/A[10]N/AN/A
    2023 DW Earth approach on 14 February 2046
    (about 8 hours before the impact scenario)
    Date & time Nominal distance
    2046-Feb-14 13:15 ± 72 minutes4730116 km[3]

    Risk corridor

    Risk corridor as it was known on 3 March 2023 with a 4-day observation arc and 55 observations. The asteroid would have most likely impacted the Pacific Ocean. At the time of the potential impactor, the asteroid is most likely to miss Earth by about 4.7 million km and has a 3-sigma uncertainty region of ± 3 million km.[21] As the uncertainty region gets smaller the probability of impact can increase and then suddenly drop to 0.

    • Risk corridor over Indonesia and the Pacific Ocean
      Risk corridor over Indonesia and the Pacific Ocean
    • Risk corridor over the Pacific Ocean and Hawaii
      Risk corridor over the Pacific Ocean and Hawaii
    • Risk corridor over Mexico and the United States
      Risk corridor over Mexico and the United States
    • Diagram showing why as the uncertainty region gets smaller the probability of impact can increase and then suddenly drop to 0.
      Diagram showing why as the uncertainty region gets smaller the probability of impact can increase and then suddenly drop to 0.

    Notes
    1. The Tunguska asteroid is estimated to have been a common stony asteroid about 50–60 meters in diameter and similar in size to 2023 DW. The Chelyabinsk meteor was only about 18 meters in diameter. Meteor Crater was created by a relatively rare (only 5% of the population) iron-nickel meteor about 50 meters in diameter.
    2. "Background risk" is defined as the average risk posed by objects of the same size or larger over the years until the date of the potential impact. A Palermo scale rating of 0 would be equal to the background risk.
    3. The risk of impact dropped significantly as the 3-sigma uncertainty region became smaller than the nominal approach distance.

    References
    1. "MPEC 2023-D71 : 2023 DW". IAU Minor Planet Center. 27 February 2023. Retrieved 5 March 2023. (K23D00W)
    2. "2023 DW". Alain Maury's Blog. Retrieved 11 March 2023.
    3. "JPL Small-Body Database Browser: (2023 DW)". Jet Propulsion Laboratory. Retrieved 20 March 2023.
    4. "2023 DW Orbit". Minor Planet Center. Retrieved 5 March 2023.
    5. "Archive of Sentry Risk Table: 2023 DW (20.3 day arc)". NASA JPL CNEOS. Archived from the original on 19 March 2023.
    6. "Archive of Sentry Risk Table: 2023 DW (1.2 day arc)". NASA JPL CNEOS. Archived from the original on 28 February 2023.
    7. "JPL Horizons: 2023 DW Target-Observer-Moon (lunar elongation) for 4–10 March 2023". JPL Horizons.
    8. "Archive (14 March 2023): ESA Risk List". European Space Agency near-earth objects coordination centre. Archived from the original on 14 March 2023.
    9. "Archive of Sentry Risk Table: 2023 DW (17.7 day arc)". NASA JPL CNEOS. Archived from the original on 16 March 2023.
    10. "Sentry (Removed Objects)". NASA/JPL Near-Earth Object Program Office. Archived from the original on 21 March 2023.
    11. "Archive of Sentry Risk Table: 2023 DW (13.8 day arc)". NASA JPL CNEOS. Archived from the original on 12 March 2023.
    12. "Archive of Sentry Risk Table: 2023 DW (2.0 day arc)". NASA JPL CNEOS. Archived from the original on 28 February 2023.
    13. "Archive of Sentry Risk Table: 2023 DW (3.9 day arc)". NASA JPL CNEOS. Archived from the original on 3 March 2023.
    14. "Archive (05 March 2023): ESA Risk List". European Space Agency near-earth objects coordination centre. Archived from the original on 5 March 2023.
    15. "Archive of Sentry Risk Table: 2023 DW (6.8 day arc)". NASA JPL CNEOS. Archived from the original on 6 March 2023.
    16. "Archive of Sentry Risk Table: 2023 DW (13.1 day arc)". NASA JPL CNEOS. Archived from the original on 11 March 2023.
    17. "Archive of Sentry Risk Table: 2023 DW (15.0 day arc)". NASA JPL CNEOS. Archived from the original on 13 March 2023.
    18. "Archive of Sentry Risk Table: 2023 DW (16.0 day arc)". NASA JPL CNEOS. Archived from the original on 14 March 2023.
    19. "Archive of Sentry Risk Table: 2023 DW (16.9 day arc)". NASA JPL CNEOS. Archived from the original on 15 March 2023.
    20. "Archive of Sentry Risk Table: 2023 DW (17.9 day arc)". NASA JPL CNEOS. Archived from the original on 16 March 2023.
    21. "JPL Horizons: 2023 DW geocentric distance and uncertainty on 14 February 2046". JPL Horizons. Archived from the original on 4 March 2023. Retrieved 20 March 2023.
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