(35396) 1997 XF11
|Discovered by||James V. Scotti
Spacewatch Project (691)
|Discovery date||6 December 1997|
|MPC designation||(35396) 1997 XF11|
|Minor planet category||Apollo NEO,
|Aphelion||2.1405 AU (Q)|
|Perihelion||0.74459 AU (q)|
|Semi-major axis||1.4425 AU (a)|
|Orbital period||1.73 yr|
|Mean anomaly||175.48° (M)|
|Longitude of ascending node||213.86°|
|Argument of perihelion||102.80°|
|Sidereal rotation period||3.259 hr|
|Apparent magnitude||8.2 to 21.7|
|Absolute magnitude (H)||16.9|
(35396) 1997 XF11 (also written (35396) 1997 XF11) is a near-Earth and Mars-crosser asteroid which, 3 months after its discovery on December 6, 1997, by James V. Scotti of the University of Arizona's Spacewatch Project, was predicted to make an exceptionally close approach to Earth on 28 October 2028. Additional precovery observations of the asteroid from 1990 were quickly found that refined the orbit and it is now known the asteroid will pass the Earth on October 26, 2028, at a distance of 0.0062 AU (930,000 km; 580,000 mi), about 2.4 times the Earth-Moon distance. During the close approach, the asteroid should peak at about apparent magnitude 8.2, and will be visible in binoculars.
(35396) 1997 XF11 is estimated to be between 1.3 km and 2.8 km in diameter.
On 11 March 1998, using a three-month observation arc, a faulty IAU Circular and press information sheet were put out that incorrectly concluded, "that the asteroid was 'virtually certain' to pass within 80% of the distance to the Moon and stood a 'small...not entirely out of the question' possibility of hitting the Earth in 2028." But by 23 December 1997 it should have been clear that XF11 had no reasonable possibility of an Earth impact. Within hours of the announcement independent calculations by Paul Chodas, Don Yeomans, and Karri Muinonen had correctly calculated that the probability of Earth impact was essentially zero, and vastly less than the probability of impact from the as-yet-undiscovered asteroids. Chodas (1999) concurs with Marsden (1999) that there was about 1 chance in a hundred thousand that XF11 could have passed through a keyhole—that is, until the 1990 precovery observations eliminated such possibilities. During the October 2002 close approach, the asteroid was observed by the 70-meter Goldstone radar dish further refining the orbit.
- "MPEC 1997-Y11 : 1997 XF11". IAU Minor Planet Center. 1997-12-23. Retrieved 2012-02-08. (J97X11F)
- "JPL Small-Body Database Browser: 35396 (1997 XF11)". Jet Propulsion Laboratory. 2012-02-02 last obs (arc=21.87 years). Retrieved 2012-02-08.
- "35396 1997 XF11". The Near-Earth Asteroids Data Base at E.A.R.N. Retrieved 2008-02-04.
- "1997XF11 Ephemerides for 26 Oct 2028". NEODyS (Near Earth Objects - Dynamic Site). Retrieved 2011-10-16.
- Piero Sicoli, Francesco Manca. "Sormano Astronomical Observatory: Table of Next Closest Approaches to the Earth by Asteroids". Astronomical Observatory of Brera. Archived from the original on 1 December 2007. Retrieved 2008-02-04.
- "NEODyS (35396) 1997XF11 Close Approaches". Department of Mathematics, University of Pisa, ITALY. Archived from the original on 2009-04-18. Retrieved 2008-02-04.
- "JPL Close-Approach Data: 35396 (1997 XF11)". 2012-02-02 last obs (arc=21.87 years). Retrieved 2012-02-08.
- "Halloween Asteroid". Science@NASA. October 31, 2002. Retrieved 2012-02-09.
- Clark R. Chapman (5 April 1998 (last update: 3 September 1998)). "The Asteroid Impact Scare of Mid-March 1998". Southwest Research Institute (SwRI). Retrieved 2012-02-08.
- Clark R. Chapman (19 August 1999). "The AsteroidsComet Impact Hazard". Southwest Research Institute (SwRI). Retrieved 2012-02-09.
- Orbital simulation from JPL (Java) / Horizons Ephemeris
- Brian Marsden: 1997 XF11: the true story (Archived from the original)
- Spacewatch animation of 1997 XF11 (Last update: 2004 April 7)
- Asteroid 1997 XF11 (Earth Close-Approach) (Solar System Dynamics; 88 day observation arc)