|Discovery date||March 3, 2000|
or // EK-i-kləs
|Alternative names||2000 EC98|
|Minor planet category||centaur|
|Epoch December 31, 2006 (JD 2454100.5)|
|Aphelion||15.687 AU (2346.719 Gm)|
|Perihelion||5.858 AU (876.276 Gm)|
|Semi-major axis||10.772 AU (1611.498 Gm)|
|Orbital period||35.36 a (12,913.822 d)|
|Average orbital speed||8.58 km/s|
|Longitude of ascending node||173.319°|
|Argument of perihelion||162.366°|
|Rotation period||26.8 h|
|Absolute magnitude (H)||9.35|
60558 Echeclus is a centaur in the outer Solar System. It was discovered by Spacewatch in 2000 and initially classified as an asteroid with provisional designation 2000 EC98 (also written 2000 EC98). Research in 2001 by Rousselot and Petit at the Besançon observatory in France showed no evidence of cometary activity, but in late December 2005 a cometary coma was detected. In early 2006 the Committee on Small Bodies Nomenclature (CSBN) gave it the cometary designation 174P/Echeclus.
60558 Echeclus is only the second comet (after Chiron) that was named as an asteroid, rather than after the name of its discoverer. Chiron is also a centaur; other centaurs are being observed for signs of a cometary coma.
Besides Chiron, three other objects are cross-listed as both comets and asteroids: 7968 Elst–Pizarro (133P/Elst–Pizarro), 4015 Wilson–Harrington (107P/Wilson–Harrington), and 118401 LINEAR (176P/LINEAR).
On 30 December 2005, when 13.1 AU from the Sun, a large chunk of Echeclus was observed to break off, causing a great cloud of dust. Astronomers have speculated this could have been caused by an impact or by an explosive release of volatile substances.
2011 outburst 
Echeclus appears to have outburst again around June 2011 when it was 8.5 AU from the Sun. On 24 June 2011, follow up imaging with the 2 meter Haleakala-Faulkes Telescope South showed the coma of Echeclus to be very close to the sky background limit.
See also 
- Wm. Robert Johnston (22 August 2008). "List of Known Trans-Neptunian Objects". Johnston's Archive. Archived from the original on 16 December 2006. Retrieved 2006-12-26.
- John Stansberry, Will Grundy, Mike Brown, Dale Cruikshank, John Spencer, David Trilling, Jean-Luc Margot (2007). "Physical Properties of Kuiper Belt and Centaur Objects: Constraints from Spitzer Space Telescope". arXiv:astro-ph/0702538 [astro-ph].
- "60558 Echeclus (2000 EC98)". JPL Small-Body Database. Jet Propulsion Laboratory. SPK-ID: 2060558. Retrieved 2008-09-09.
- "AstDys (60558) Echeclus Ephemerides". Department of Mathematics, University of Pisa, Italy. Retrieved 2010-06-28.
- "Homepage of the VdS-Fachgruppe Kometen". Archived from the original on 24 April 2006. Retrieved 2006-04-18.
- Dual-Status Objects
- Hecht, Jeff (11 April 2006). "Hybrid comet-asteroid in mysterious break-up". NewScientist.com news service. Retrieved 2006-04-18.
- Giovanni Sostero & Ernesto Guido (June 1, 2011). "Outburst of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-01.
- Giovanni Sostero & Ernesto Guido (June 9, 2011). "Follow-up of 174P/Echeclus bright phase". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-09.
- Nick Howes, Giovanni Sostero and Ernesto Guido (June 24, 2011). "Further follow-up of 174P/Echeclus". Team of observers of Remanzacco Observatory in Italy. Retrieved 2011-06-24.
- Horner, J.; Evans, N.W.; Bailey, M. E. (2004). "Simulations of the Population of Centaurs I: The Bulk Statistics". Monthly Notices of the Royal Astronomical Society 354 (3): 798. arXiv:astro-ph/0407400. Bibcode:2004MNRAS.354..798H. doi:10.1111/j.1365-2966.2004.08240.x.
- Orbital simulation from JPL (Java) / Ephemeris
- Elements and Ephemeris for 174P/Echeclus (IAU Minor Planet Center)
- BAA Comet Section : Comets discovered in 2006
- 60558 - 0174P/ Echeclus (2011 June 8)
- Comet 174P Echeclus chased by Asteroid 2716 Tuulikki (Animation by Joseph Brimacombe on 30 May 2011)
|Periodic comets (by number)|