(450894) 2008 BT18

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(450894) 2008 BT18
Discovery [1]
Discovered by LINEAR
Discovery site Lincoln Lab's ETS
Discovery date 31 January 2008
MPC designation (450894) 2008 BT18
2008 BT18
Apollo · NEO · PHA
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 60.59 yr (22,132 days)
Aphelion 3.5402 AU
Perihelion 0.9037 AU
2.222 AU
Eccentricity 0.5933
3.31 yr (1,210 days)
0° 17m 51.36s / day
Inclination 8.1317°
Known satellites 1 [a][b]
Earth MOID 0.0106 AU
Physical characteristics
Dimensions 0.6 km[a]
0.650 km (calculated)[2]
0.630 km [3]
2.726±0.007 h[c]
0.20 (assumed)[2]
S[2] · V[c]

(450894) 2008 BT18 is an eccentric, stony binary[b] asteroid of the Apollo group, classified as near-Earth object and potentially hazardous asteroid, approximately 0.6 kilometers in diameter. It was discovered on 31 January 2008, by the U.S. LINEAR program at Lincoln Laboratory's Experimental Test Site, Socorro, New Mexico.[4]

The S-type asteroid is also classified as a V-type by NASA's Infrared Telescope Facility, IRTF.[c] It orbits the Sun at a distance of 0.9–3.5 AU once every 3 years and 4 months (1,210 days). Its orbit has an eccentricity of 0.59 and an inclination of 8° with respect to the ecliptic.[1] The first precovery was taken at Palomar's Digital Sky Survey (DSS) in 1953, extending the asteroid's observation arc by 55 years prior to its discovery.[4] The asteroid has a low Earth minimum orbit intersection distance of 0.0106 AU (1,590,000 km). On 14 July 2008, it transited Earth within 0.015 AU, or 5.9 lunar distances.[1]

A rotational light-curve for this body was obtained from photometric observations made by astronomer Alberto Betzler at Salvador, Brazil, in July 2008. The fragmentary light-curve gave a rotation period of 2.726±0.007 hours with a brightness variation of 0.04 in magnitude (U=1).[c]

On 6 and 7 July 2008, research conducted using the Arecibo Observatory produced evidence that this is a binary system with an asteroid moon.[5] 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.[a][b] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for stony asteroids of 0.20 and calculates a diameter of 650 meters, based on an absolute magnitude of 18.3.[2]


  1. ^ a b c Benner (2008) web: diameter 0.6 kilometers. Central Bureau Electronic Telegrams, No. 1450, #1 (2008). Edited by Green, D. W. E Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (450894)
  2. ^ a b c Central Bureau for Astronomical Telegrams, No. 1450, from 29 July 2008:

    Arecibo (2380-MHz, 12.6-cm) and Goldstone (8560-MHz, 3.5-cm) radar observations during July 6, 7, and 11 reveal that minor planet 2008 BT_18 (cf. MPECs 2008-C03, 2008-H06; MPO 140193) is a binary system. Preliminary estimates for the component diameters are about 0.6 km and > 200 m. The maximum distance between the components on July 11 is at least 1.5 km.

    Reported by: L. A. M. Benner, Jet Propulsion Laboratory (JPL), California Institute of Technology (CIT); M. C. Nolan and E. S. Howell, Arecibo Observatory, National Astronomy and Ionosphere Center; C. Magri, University of Maine at Farmington; J. D. Giorgini, S. J. Ostro, and M. Brozovic, JPL/CIT; M. W. Busch, CIT; J. L. Margot and P. A. Taylor, Cornell University; M. K. Shepard, Bloomsburg University; L. M. Carter, Smithsonian Institution; and T. M. Becker, Lehigh University CBET No. 1450
  3. ^ a b c d Betzler (2009) web: rotation period 2.726±0.007 hours with a brightness amplitude of 0.04 mag. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (450894) Observations of V-type Binary Near-Earth Asteroids 2006 VV2 and 2008 BT18
  1. ^ a b c d e "JPL Small-Body Database Browser: 450894 (2008 BT18)" (2015-10-17 last obs.). Jet Propulsion Laboratory. Retrieved 21 May 2016. 
  2. ^ a b c d e "LCDB Data for (450894)". Asteroid Lightcurve Database (LCDB). Retrieved 21 May 2016. 
  3. ^ Johnston, Wm. Robert (September 20, 2014). "2008 BT18". Johnston's Archive. Retrieved 14 November 2015. 
  4. ^ a b "450894 (2008 BT18)". Minor Planet Center. Retrieved 21 May 2016. 
  5. ^ "2008 BT18 Goldstone Radar Observations Planning". NASA Jet Propulsion Laboratory. Retrieved 2008-08-01. 

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