Positions for about 5000 asteroid were computed for every day in a given year for those reaching V = 16 or brighter. For a given asteroid and date, its position was compared against the position on the same data for the remaining asteroids.
If an initial approach within 0.5° was found, a three position interpolation was used to find the approximate time of closest approach. Then the perturbed positions for both asteroids were computed at 1-minute intervals ±3 hours of the estimated time of closest approach. Interpolation was used to find the exact date and time of minimum distance.