 Radar image of2008 BT18 and its satellite fromArecibo Observatory in July 2008 | |
| Discovery[1] | |
|---|---|
| Discovered by | LINEAR |
| Discovery site | Lincoln Lab's ETS |
| Discovery date | 31 January 2008 |
| Designations | |
| (450894)2008 BT18 | |
| 2008 BT18 | |
| Apollo · NEO · PHA[1][2] | |
| Orbital characteristics[1] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 60.59 yr (22,132 days) |
| Earliestprecovery date | 14 March 1955 |
| Aphelion | 3.5401AU |
| Perihelion | 0.9030 AU |
| 2.2216 AU | |
| Eccentricity | 0.5935 |
| 3.31yr (1,209 days) | |
| 284.48° | |
| 0° 17m 51.72s / day | |
| Inclination | 8.1338° |
| 107.67° | |
| 139.28° | |
| Knownsatellites | 1[3][a][b] |
| Earth MOID | 0.0108 AU · 4.2LD |
| Physical characteristics | |
| Dimensions | 0.6 km[3][a] 0.650 km(calculated)[4] |
| 2.726±0.007h[5] | |
| 0.20(assumed)[4] | |
| V[5][6] · S(assumed)[4] | |
| 18.3[1][4] | |
(450894) 2008 BT18 is a sub-kilometerasteroid and synchronousbinary system, classified asnear-Earth object andpotentially hazardous asteroid of theApollo group. It was discovered on 31 January 2008, by theLINEAR program atLincoln Laboratory's Experimental Test Site near Socorro, New Mexico, United States.[2] The eccentric asteroid measures approximately 600 meters in diameter and has a composition of abasaltic achondrite.[6]
In 2008, itsminor-planet moon, designatedS/2008 (450894) 1, was discovered by radar astronomers. It measures approximately 200 meters in diameter, or one third of its primary.[3][b]
2008 BT18 orbits the Sun at a distance of 0.9–3.5 AU once every 3 years and 4 months (1,209 days). Its orbit has aneccentricity of 0.59 and aninclination of 8° with respect to theecliptic.[1] Published by theDigitized Sky Survey, a firstprecovery was taken atPalomar Observatory in 1955, extending the asteroid'sobservation arc by 53 years prior to its discovery.[2]
The asteroid has a low Earthminimum orbit intersection distance of 0.0108 AU (1,620,000 km) which corresponds to 4.2lunar distances (LD). On 14 July 2008, it transited Earth within 0.015 AU (5.9 LD).[1]
2008 BT18 has been characterized as aV-type asteroid by astronomers using theSpeX spectrograph atNASA Infrared Telescope Facility, IRTF.[5][6]
A rotationallightcurve for2008 BT18 was obtained from photometric observations made by astronomer Alberto Silva Betzler at Salvador, Brazil, in July 2008. The lightcurve gave arotation period of2.726±0.007 hours with a brightness variation of 0.04 inmagnitude (U=1).[5]
On 6 and 7 July 2008, research conducted using theArecibo Observatory produced evidence that2008 BT18 is a synchronousbinary asteroid with aminor-planet moon in its orbit. The secondary component has a diameter of at least 200 meters, about 33% the size of and up to 1.5 kilometers apart from its primary.[3][a][b] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 650 meters, based on anabsolute magnitude of 18.3.[4]
There are more than60 binary near-Earth objects known to exist (2016).
On 26 July 2008, observations at the IRTF using the SpeX-spectrograph showed that2008 BT18 is abasaltic achondrite, suggesting that its parent body was subjected to sufficiently high temperatures to produce aeutectic melt.[6] The body's surface is thought to be dominated by iron-richorthopyroxenes with little or noolivine.[6]
As of 2017, thisminor planet remains unnamed.[2]
