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(52768) 1998 OR2, provisional designation 1998 OR2, is an asteroid on an eccentric orbit, classified as near-Earth object and potentially hazardous asteroid of the Apollo group, approximately 2 kilometers in diameter. It was discovered on 24 July 1998, by astronomers of the NEAT program at the Haleakala Observatory, Hawaii.[2] It is one of the brightest and therefore largest potentially hazardous asteroids known to exist.[8] With an observation arc of 31 years, the asteroid has a well determined orbit and the trajectory is well known through the year 2197.[1]

(52768) 1998 OR2
Discovery [1][2]
Discovered byNEAT
Discovery siteHaleakala Obs.
Discovery date24 July 1998
Designations
MPC designation(52768) 1998 OR2
1998 OR2
Apollo · NEO · PHA[1][2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc30.32 yr (11,076 days)
Earliest precovery date30 June 1987 (Siding Spring Observatory)
Aphelion3.7428 AU
Perihelion1.0167 AU
2.3798 AU
Eccentricity0.5728
3.67 yr (1,341 days)
103.81°
0° 16m 6.6s / day
Inclination5.8796°
27.064°
174.45°
Earth MOID0.0157 AU · 6.1 LD
Physical characteristics
Mean diameter
2.15 km (calculated)[3]
3.198±0.006 h[4]
4.112±0.002h[5]
0.20 (assumed)[3]
L[6] · S (assumed)[3]
15.7[3] · 15.7±0.1[4] · 15.8[2] · 15.9[1] · 16.15±0.10[7]

Orbit and classificationEdit

1998 OR2 is a member of the dynamical Apollo group,[1][2] which are Earth-crossing asteroids. Apollo asteroids are the largest subgroup of near-Earth objects.

It orbits the Sun at a distance of 1.0–3.7 AU once every 3 years and 8 months (1,341 days; semi-major axis of 2.38 AU). Its orbit has a high eccentricity of 0.57 and an inclination of 6° with respect to the ecliptic. With its sufficiently large aphelion, this asteroid is also classified as a Mars-crosser, crossing the orbit of the Red Planet at 1.66 AU.[1]

The body's observation arc begins with a precovery published by the Digitized Sky Survey an taken at the Siding Spring Observatory on June 1986, or more than one year prior to its official discovery observation at Haleakala.[2]

Close approachesEdit

With an absolute magnitude of approximately 15.8,[2] 1998 OR2 is one of the brightest and presumably largest known potentially hazardous asteroids (see PHA-list).[8] It has an Earth minimum orbital intersection distance of 0.0157 AU (2,350,000 km), which translates into 6.1 lunar distances (LD).[1] On 16 April 2079, this asteroid will make a close near-Earth encounter at a safe distance of 0.0118 AU (4.6 LD), and pass the Moon at 0.009 AU (3.58 LD).[1]

History of close approaches of large near-Earth objects since 1908 (A)
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 15.30 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≈6400 km).
(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

Physical characteristicsEdit

According to observations by the NASA IRTF telescope during the ExploreNEOs Warm Spitzer program, 1998 OR2 is a rather rare L-type asteroid.[6]

Rotation periodEdit

In 2009, rotational lightcurves of 1998 OR2 were obtained from photometric observations by astronomers in Salvador, Brazil, and during the Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS). Lightcurve analysis gave a rotation period of 3.198 and 4.112 hours with a brightness amplitude of 0.29 and 0.16 magnitude, respectively (U=2/2+).[4][5]

Diameter and albedoEdit

The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 2.15 kilometers based on an absolute magnitude of 15.7.[3]

NamingEdit

As of 2018, this minor planet has not been named.[2]

ReferencesEdit

  1. ^ a b c d e f g h i "JPL Small-Body Database Browser: 52768 (1998 OR2)" (2018-11-10 last obs.). Jet Propulsion Laboratory. Retrieved 24 January 2018.
  2. ^ a b c d e f g h "52768 (1998 OR2)". Minor Planet Center. Retrieved 24 January 2018.
  3. ^ a b c d e "LCDB Data for (52768)". Asteroid Lightcurve Database (LCDB). Retrieved 24 January 2018.
  4. ^ a b c Betzler, Alberto Silva; Novaes, Alberto Brum (October 2009). "Photometric Observations of 1998 OR2, 1999 AQ10, and 2008 TC3". The Minor Planet Bulletin. 36 (4): 145–147. Bibcode:2009MPBu...36..145B. ISSN 1052-8091. Retrieved 24 January 2018.
  5. ^ a b Koehn, Bruce W.; Bowell, Edward G.; Skiff, Brian A.; Sanborn, Jason J.; McLelland, Kyle P.; Pravec, Petr; et al. (October 2014). "Lowell Observatory Near-Earth Asteroid Photometric Survey (NEAPS) - 2009 January through 2009 June". The Minor Planet Bulletin. 41 (4): 286–300. Bibcode:2014MPBu...41..286K. ISSN 1052-8091. Retrieved 24 January 2018.
  6. ^ a b 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" (PDF). Icarus. 228: 217–246. arXiv:1310.2000. Bibcode:2014Icar..228..217T. doi:10.1016/j.icarus.2013.10.004. Retrieved 24 January 2018.
  7. ^ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 24 January 2018.
  8. ^ a b "List of the Potentially Hazardous Asteroids (PHAs)". Minor Planet Center. Retrieved 24 January 2018.

External linksEdit