@Giuseppe_r_P @tony873004 Uncertainty tends to spread most in the “along track” direction.

Info on how JWST will be used to observe asteroid 2024 YR4

@YR4tracker @cosmos4u @gblasco78 @AstroKirsten @mEitHan NEODyS has dropped back to 1.6% (for now).

@DJSnM @astro_alexandra If we used the SDT frequency, the current risk from 2024 YR4 would be about 8 times the background risk.

@janis_ans @YourMJK @0xAce0fDef1 @JaustinUMD @DJSnM An impact is only possible at the crossing point. We know exactly when Earth passes through the crossing point, so we know what Earth’s orientation will be. At the moment the 3-sigma timing uncertainty for 2024 YR4 is around +/- 15 hours but the impact zone is 10 minutes.

@robgoldbergo @WatsonLadd @StatisticUrban 31 million seconds in a year, so a velocity change of 3 mm/s means a position difference of about 100 km after 1 year, 400 km after 4 years. Probably need a dV of at least 100 mm/s to move it off an Earth impact.

@lookner The uncertainty region in 2032 is still quite large (~+/-900,000 km at 3-sigma). It is shrinking slowly as more data comes in, so the impact probability goes up. May need the uncertainty to get down to 100,000 km before we get the point where the risk will fall to zero.

@nitoxwulgax Still just a consequence of the shrinking uncertainty zone, now down to about +/- 900,000 km (3-sigma). Latest observations have moved the nominal point back within 100,000 km. Looks like the probability will rise further before falling (most likely).

@coias_t09 Are these the images Sam Deen was referring to in this thread on the MPML?

@Cosmic_Penguin @Astro_Jonny An impact by Apophis in 2029 was ruled out on 27 Dec 2004 with the reporting of precovery observations from 15 Mar 2004. It had only been on the risk table for about a week. It lingered long after that at much lower risk levels for other possibilities in 2036 and then 2068.

@RocketDIYerBen @astroEdLu Checked JPL’s HORIZONS and it gives the following Cartesian positions and uncertainties at the current day: JD 2460711.5 = A.D. 2025-Feb-05 00:00 TDB X : -133,911,356 +/- 614 km Y: 150,466,101 +/- 1125 km Z: -7,682,975 +/- 182 km JPL solution 44

@jadynjc3 @Astro_Jonny Lengthening the observational arc is the main way to reduce the uncertainty. Radar observations can help because they give high precision on line of sight distance and velocity. 2024 YR4 is too far away for radar. Would have possible around Christmas if we’d known it was coming.

@AudacityOfHoops @eternalism_4eva @Astro_Jonny Basically that’s where the crossing point is. If there’s going to be an impact, it has to happen then. The uncertainty is in the along track direction, so whether the asteroid will pass before or behind. The timing uncertainty for the asteroid is about +/- 20 hours at present.

@is_OwenLewis @Astro_Jonny December 2024. The 2032 encounter was raised to Torino Scale 3 in January 2025.

@RocketDIYerBen @astroEdLu Observations in optical wavelengths by ground-based telescopes. Typically in the 2-m class at present as it is around magnitude 23.

@TuelTaylor @astroEdLu It is estimated to have a mass of around 200,000 tons and would need a delta-V of about 13 km/s.

@JulesVictor5 @astro_alexandra Well, the estimated energy (~ 8 Mt TNT-equivalent) is similar to the Tunguska event, but that is based on assumptions about the size and density that could be off by a factor of about 2.