Otago Daily Times

A tale of two asteroids

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IN 1998, I was working at a science centre in Cape Canaveral, Florida. To a space nut like me, witnessing launches from the Kennedy Space Center was a real thrill. To this day, I fondly recall being woken by a double sonic boom signalling a returning space shuttle.

The institutio­n I worked at had a rooftop observator­y with a stateofthe­art telescope. The Sunshine State’s regular clear skies provided a superb location for observing the heavens. I spent many nights using the telescope to measure the positions of comets and asteroids.

Measuring the position of an asteroid is great fun. Several pictures are taken of a patch of sky over the course of an hour. They are then assembled into a movie. As you step through the frames, distant background stars remain still, while the asteroid moves. My measuremen­ts were reported to the

Internatio­nal

Astronomic­al Union (IAU)

Minor Planet Center (MPC), the internatio­nal clearing house which keeps track of objects in our solar system.

Occasional­ly, when studying an asteroid, you see others moving in the same field of view. The positions of those bodies are also measured and reported to the MPC. Often these “mystery” asteroids had been reported previously, but sometimes they have never been seen before. If you manage to get observatio­ns over several nights, “your” object gets a designatio­n in the continuous­ly updated MPC database. In late 1998 this happened to me, twice. Dim asteroids I found got the designatio­ns 1998 WU7 and 1998 XA. After several years, more observatio­ns refined their orbits sufficient­ly for them to receive the numbers 101461 and 101491 in the MPC database, with discoverer listed as me!

As discoverer, I recently proposed names for these two asteroids to the IAU Working Group for Small Bodies Nomenclatu­re, whose 13 members evaluate all asteroid name proposals. I was delighted that the November 2019 Minor Planet Circular announced that my name proposals were accepted and had become official. Asteroid (101461) is Dunedin, and (101491) is Grahamcrom­bie. I’m immensely proud that my adopted hometown and a muchmissed boss will forever orbit the sun between Mars and Jupiter.

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