Summer Science Program - Astronomical Work

Astronomical Work

For the first 50 years of the program, students took photographic images of main-belt asteroids (between the orbits of Mars and Jupiter). Starting in 2009 students took digital images of (much fainter) near-earth asteroids (inside the orbit of Mars). The process of orbit determination is conceptually the same in both cases. First students take a series of images of asteroids. After identifying the asteroid, its position on the image relative to known stars is carefully calculated. That relative position is then used to determine the position of the asteroid in celestial coordinates (right ascension and declination) at the exact time the image was taken. The series of positions as the asteroid moves across the sky allows the student to fit an approximate orbit to the asteroid. The measured asteroid coordinates (not the calculated orbital elements) are submitted to the Harvard-Smithsonian Center for Astrophysics.

Over the decades SSP students have done their orbit determination calculations on mechanical calculators (1960s), then electronic calculators (1970s), then "mini-computers" (1980s), then personal computers (1990s and 2000s). In recent years they write their orbit determination programs in the Python programming language, employing the Gaussian method.