Asteroid 2023 NT1 passed by the Earth at a distance of about 100 230 km (26% of the average distance between the Earth and the Moon or 0.07% of the distance between the Earth and the Sun), with a velocity of about 11.28 km per second, slightly after 10.10 am GMT on Thursday 13 July 2023. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a major threat. 2023 NT1 has an estimated equivalent diameter of 19-60 m (i.e. it is estimated that a spherical object with the same volume would be 19-60 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) between 25 and 5 km above the ground, with only fragmentary material reaching the Earth's surface; although being directly beneath such an object when it exploded would probably not be particularly pleasant. The 2013 Chelyabinsk meteor had an estimated diameter of about 20 m (i.e. at the smaller end of the estimated size range of 2023 NT1); an object 60 m in diameter would produce an explosion thirty times as large and five times as close, likely to cause significant damage within a localised area.
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2023 NT1 was discovered on 14 June 2023 (the day after its closest approach to the Earth) by Asteroid Terrestrial-impact Last Alert System (ATLAS) South Africa Telescope at the South African Astronomical Observatory in Sutherland, Northern Cape Province. The designation 2023 NT1 implies that the asteroid was the 44th object (asteroid T1 - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 26, A2 = 51, etc., which means that T1 = (25 x 1) + 19 = 44) discovered in the first half of July 2023 (period 2023 N - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).
2023 NT1 is calculated to have a 911 day (2.49 year) orbital period, with an elliptical orbit tilted at an angle of 4.85° to the plain of the Solar System which takes in to 0.91 AU from the Sun (91% of the distance at which the Earth orbits the Sun) and out to 2.77 AU (2.77 times the distance at which the Earth orbits the Sun, considerably more than the distance at which the planet Mars orbits). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).
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This means that 2023 NT1 has occasional close encounters with the Earth, with the last having happened in July 2018 and the next predicted for August 2049.
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