Scout: NEOCP Hazard Assessment

Introduction

Scout provides trajectory analysis and hazard assessment for recently detected objects on the Minor Planet Center’s Near-Earth Object Confirmation Page (NEOCP). Objects on these pages are unconfirmed; their designations are user-assigned and unofficial. These objects could be real asteroids, but they cannot be officially designated until they are confirmed by additional observations. In fact, it is very possible that some of these “objects” are not real, but rather observing artifacts. If the Minor Planet Center receives enough confirming observations to make sure that an object is a real asteroid, the object is given an official designation and disappears from the NEOCP and Scout. Objects that remain unconfirmed are eventually removed from the NEOCP and also disappear from Scout.

Scout continually monitors the objects on the NEOCP, and for each provides the following orbital, ephemeris, and hazard assessment information.

• The number of observations and the length of the observed arc
• The RMS of the weighted residuals for the best fitting orbit
• Coarse indicators of absolute magnitude H, MOID, close approach distance, velocity relative to Earth (when defined)
  • Note that these quantities can be extremely uncertain for short arcs
• Current ephemeris information updated every 15 minutes: Coarse RA, DEC, V-band magnitude, solar elongation, plane-of-sky (POS) rate of motion, 1-sigma POS uncertainty, and POS uncertainty tomorrow
• Likelihood scores between 0 and 100 for PHA, NEO, geocentric, cometary (Tisserand parameter TJ < 3), and Interior-to-Earth orbits
• A rating to categorize the chances of an impact on Earth (not defined for arcs shorter than 20 minutes or with less than three observations):
  0. Negligible
  1. Small
  2. Modest
  3. Moderate
  4. Elevated

Because of the generally short observation arcs and the uncertain quality of the astrometry, the reported impact ratings and scores are meant to identify interesting objects rather than provide a rigorous probability assessment.