What's going on with NEA 2012 TC4?


Current Lightcurve

Secular lightcurve of 2012 TC4 in 2017
PDF Version
Data (MPC database)

Status Updates

2017 Sep 18: Astrometry received from Subaru (Aug 27), Pan-STARRS (Sep 14 & 17) and OGS (Sep 17). The current orbit (JPL#36) gives a close approach distance of 50,168 ±40 km and the estimated time of close approach 2017-10-12 05:40:55 ±20 s UT.

2017 Sep 15: PanSTARRS has provided further astrometry from Sept. 14, UT. The current orbit (JPL#34) gives a close approach distance of 50,179 ±66 km and the estimated time of close approach 2017-10-12 05:40:56 ±22 s UT.

2017 Sep 12: Bill and Eileen Ryan of Magdalena Ridge provided further astrometry from Sept. 12, UT. This produced only a small change on the orbital geometry (JPL#32) with a close approach distance of 50,174 ±70 km and the estimated time of close approach 2017-10-12 05:40:56 ±22 s UT.

2017 Sep 11: Bill and Eileen Ryan of Magdalena Ridge provided further astrometry from Sept. 11, UT.

Orbit solution JPL#30 is now available and includes these observations. It also contains nongravitational perturbations on 2012 TC4 (Yarkovsky drift and radiation pressure). Although the astrometry is not yet accurate enough to detect these effects, the trajectory uncertainty has decreased to the point that they may soon be measurable.

The orbit update had little effect on the approach geometry, though it did reduce the uncertainties. Close approach distance is 50,169 ±83 km and the estimated time of close approach is 2017-10-12 05:40:55 ±23 s UT. Uncertainties are 3-sigma.

2017 Sep 05: Today the MPC published new observations of 2012 TC4 that Bob McMillan obtained at Kitt Peak on Aug 30 and 31. JPL solution 28 is now available on the JPL Small-Body Database and Horizons and includes these new observations, which further reduce uncertainties for the October close approach.

The estimated close approach distance is 50170 km with a 3-sigma uncertainty of ±230 km and the estimated time of close approach is 2017-10-12 05:40:55 UT with a 3-sigma uncertainty of ±35 seconds.

As a side note, the impact probability for 2050 has increased to 2/1000. Hopefully the data collected during this campaign will allow us to rule out the impact!

Recovery Status

6 August 2017: [Recovered] Owing to the latest VLT observations by O. Hainaut, D. Koschny, and M. Micheli, 2012 TC4 is now recovered! Initial observations of a potential object found on July 27, 2017 were confirmed on July 31 and August 5, 2017. The JPL small database browser now posts the close approach distance for 2017 Oct. 12 as 0.000335 AU (~50100 km) based on the addition of M. Micheli's and O. Hainaut's astrometric measurements, and the object's H-magnitude value is near 26.7, corresponding to a diameter of around 15 meters for an object with an albedo of about 15%. The recovery's Minor Planet Electronic Circular is here .

28 July 2017: [Still unobserved] Currently, the asteroid has not been recovered on its 2017 apparition, though with a predicted mag >26, it was not expected to have been seen yet. As shown in the plot below, it is expected to become bright enough in the next couple weeks to be recovered. The plot also shows the size of the current positional uncertainty, and how its apparent size projected on the sky will change until the asteroid is recovered.

2012 TC4 position uncertainty