Apostolos Christou and David Asher at the Armagh Observatory together with summer student Sharon McClure (Glenlola Collegiate, Bangor, Co. Down) observed and imaged the unusual near-Earth asteroid 2000PH during its close approach to the Earth around 27 July 2004. The observations were carried out remotely using the new 2m aperture Faulkes telescope situated on the 10,000-foot summit of Haleakala, on the island of Maui in Hawaii. They formed part of Sharon McClure's summer work experience project, supported by the Nuffield Science Bursary Scheme, which is run by the Sentinus programme in the University of Ulster at Jordanstown. The aim of the observations was to image the asteroid using the Faulkes Telescope, and determine its changing brightness and position in space as the small object passed near the Earth on its orbit about the Sun.
2000PH was discovered on 3 August 2000 by the MIT Lincoln Laboratory near-Earth Asteroid Research (LINEAR) project at the White Sands Missile Range in Socorro, New Mexico, USA. It is one of approximately 100,000 asteroids now known with reasonably well-determined orbits, many of them discovered by the US-based LINEAR programme within the past few years. On the 27 July 2004, owing to its close proximity to the Earth at that time (just 6 times the distance to the Moon or approximately 2,300,000km), the asteroid appeared to race across the sky, covering a distance equal to the apparent diameter of the Moon every hour.
The Faulkes Telescope Project (see http://faulkes1.astro.cf.ac.uk/) is a private educational facility that will eventually consist of two research quality 2m telescopes, one in Hawaii and the other to be constructed in Australia. It is intended that school pupils will be able to select their celestial targets and operate the telescopes themselves during normal school hours, and carry out their own research projects. The Armagh Observatory accessed the Faulkes Telescope in Hawaii with the assistance of Robert Hill of the Armagh Planetarium through the Planetarium's role as a regional centre for the Faulkes Telescope Project in Northern Ireland.
One of the results of this project was a set of images showing the asteroid's relatively rapid motion across the sky during its close approach to Earth (see Figure 8). One way to discover the asteroid, and to see its motion against the background stars during a few minutes, is to look at the images shown in Figure 8 so as to `fuse' the separate images into a central third image. Any slight movement will cause the asteroid to appear to jump out of the fused image, while the fixed stars remain stationary.