I’ve been looking into this event, and, for the record, there seems to be an error in Bill Barton’s original post.
On 24 March the figures that were being given by news outlets for this close approach were that the asteroid would pass the Moon at 515,000km and Earth at 168,000km (not 68,000km). In fact this prediction was quite accurate, the miss distance being 175,000km. The object was measured at 70m diameter.
The BBC news article Bill linked to was revised on 25 March, but see, for example, the Guardian article:
https://www.theguardian.com/science/2023/mar/24/city-killer-asteroid-to-pass-harmlessly-between-earth-and-moon
