The interactive map below shows our current prediction for the stellar occultation by (21900) Orus on 2021 August 13 UT. The prediction is based on a Gaia DR2 position for the star, corrected for parallax and proper motion, and the v20200901193809 orbit estimate for Orus, which has a 1-sigma cross-track uncertainty of 15.7 km.
Geocentric mid-time of the event is 02:55:31 UT. Star position is RA 02:07:01.5, Dec +20:36:56 (J2000), and its magnitude is 16.88. Orus is moving at 6 km/s with respect to the star and its diameter is estimated to be 51 km, so central chords are expected to last 8.1 seconds. Orus' magnitude is predicted to be 17.0 at event time, so it will be the same brightness as the star.