(277475) 2005 WK4

(277475) 2005 WK₄, provisional designation 2005 WK₄, is a stony, sub-kilometer asteroid, classified as near-Earth object and potentially hazardous asteroid of the Apollo group that passed Earth within 8.2 lunar distances on 8 August 2013.^[7] It was discovered on 27 November 2005, by astronomers of the Siding Spring Survey at Siding Spring Observatory, Australia.^[2]

(277475) 2005 WK₄

2005 WK4 imaged 30 times by radar at Goldstone on 8 August 2013
Discovery[1][2]
Discovered by	Siding Spring Srvy.
Discovery site	Siding Spring Obs.
Discovery date	27 November 2005
Designations
MPC designation	(277475) 2005 WK4
Alternative designations	2005 WK4
Minor planet category	Apollo · NEO · PHA[1][2]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc	8.71 yr (3,180 days)
Aphelion	1.2506 AU
Perihelion	0.7707 AU
Semi-major axis	1.0106 AU
Eccentricity	0.2374
Orbital period (sidereal)	1.02 yr (371 days)
Mean anomaly	81.040°
Mean motion	0° 58m 12.36s / day
Inclination	9.8433°
Longitude of ascending node	138.14°
Argument of perihelion	74.063°
Earth MOID	0.0037 AU · 1.4 LD
Physical characteristics
Dimensions	0.25±0.05 km[lower-alpha 1] 0.284 km (calculated)[3]
Synodic rotation period	2.595±0.002 h[4] 2.7±0.1 h[lower-alpha 1] 2.73±0.05 h[5]
Geometric albedo	0.20 (assumed)[3]
Spectral type	Sk[6] · S (assumed)[3] B–V = 0.677±0.025[6] V–R = 0.446±0.019[6] V–I = 0.750±0.024[6]
Absolute magnitude (H)	20.1[1][3]

Description

In August 2013, 2005 WK₄ was radar-imaged by the Deep Space Network dish at Goldstone Observatory, United States,^[7] and had been observed previously at Arecibo Observatory in July 2012 (this was not a close approach though).^[8]

Physical characteristics

2005 WK₄ measures approximately 250 meters in diameter, and has a rotation period of 2.595 hours.^{[3][4][lower-alpha 1]} Its spectral type is that of an Sk-subtype, which transitions from the stony S-type to the uncommon K-type asteroids.^[6]

See also

• List of asteroid close approaches to Earth in 2013

Notes

1. Benner (2013): radiometric observations: mean diameter 0.25±0.05 km; rotation period 2.7±0.1 hours. Summary figures at the LCDB; also see NASA news report

References

1. "JPL Small-Body Database Browser: 277475 (2005 WK4)" (2014-08-12 last obs.). Jet Propulsion Laboratory. Retrieved 20 January 2018.
2. "277475 (2005 WK4)". Minor Planet Center. Retrieved 20 January 2018.
3. "LCDB Data for (277475)". Asteroid Lightcurve Database (LCDB). Retrieved 20 January 2018.
4. Stephens, Robert D. (January 2014). "Asteroids Observed from CS3: 2013 July-September". The Minor Planet Bulletin. 41 (1): 13–15. Bibcode:2014MPBu...41...13S. ISSN 1052-8091. Retrieved 20 January 2018.
5. Behrend, Raoul. "Asteroids and comets rotation curves – (277475)". Geneva Observatory. Retrieved 20 January 2018.
6. Hicks, M.; Buratt, B.; Carcione, A.; Borlase, R. (August 2013). "Broadband Photometry Of The Potentially Asteroid 277475 (2005 WK4) and Corrected 52762 (1998 MT24) Colors". The Astronomer's Telegram. 5311 (5311): 1. Bibcode:2013ATel.5311....1H. Retrieved 20 January 2018.
7. "Radar Images of Asteroid 2005 WK4". NASA. Archived from the original on 24 September 2021.
8. 2005WK4 - Background

External links

• Radar images
• Radar Images of Asteroid 2005 WK4, NASA news, 15 August 2013
• Optical image, virtualtelescope.eu
• Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
• Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
• (277475) 2005 WK4 at NeoDyS-2, Near Earth Objects—Dynamic Site
  • Ephemerides · Observation prediction · Orbital info · MOID · Proper elements · Observational info · Close approaches · Physical info · Orbit animation
• (277475) 2005 WK4 at ESA–space situational awareness
  • Ephemerides · Observations · Orbit · Physical properties · Summary
• (277475) 2005 WK4 at the JPL Small-Body Database
  • Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters