IAWN will conduct a campaign to check the accuracy of the observation times reported by asteroid observers. The goal of the campaign is to provide an opportunity for observers to voluntarily check their timing accuracy by observing near-Earth asteroid 2019 XS on November 9th and 10th, 2021, when the asteroid will be as close as 1.5 lunar distances to Earth. The high plane-of-sky rate of motion during the encounter enables the assessment of the accuracy of the reported observation times. Astrometry obtained as part of this campaign should be submitted to the Minor Planet Center as part of regular submission process by November 12th, 2021. Observers interested in contributing to the campaign are encouraged to sign up at the IAWN website ( Pre- and post-flyby teleconferences will be organized to answer any questions and discuss the outcomes of the campaign. Other asteroids with high rates of motion could be considered as additional targets of the campaign in 2022. IAWN campaign coordinator Vishnu Reddy ( is the point of contact for this campaign.

  • Close approach to Earth: 2021 November 9 at 3:38 UT, distance = 1.5 LD
  • Observations on 2021 November 9-11. Maximum rate of motion 3.8 arcsec/s
  • Submit astrometry to the MPC by 2021 November 12 at 23:59 EST. ADES is the preferred format.


Fig7 From Reddy et al 2019Similar to the 2012 TC4 analysis in Reddy et al (2019), astrometric accuracy will be estimated using cross-track residuals. Along-track residuals will be used to assess the timing accuracy. Registrants will receive summary timing analysis for their submissions.


By registering for this campaign you will be provided with the summary analysis for the observations you reported to the MPC.


  • Register (by 2021 Nov 12, 23:59 UT) if you plan on observing 2019 XS.
  • Observe 2019 XS sometime over 2021 Nov 9-11.
  • Submit your observation reports as usual to the MPC.
  • Our team will then look at the observations submitted to the MPC and analyse.
  • Registered campaign observers will receive a report back by the end of the year.