Alongside orbit determination, I planned to determine the rotational period of asteroids. As asteroids rotate, the light reflected from the Sun can change in magnitude, due to the uneven shape of asteroids which reflect light at different levels at different times. This change can be plotted against time to reveal the rotational period.

My plan was to first test out our methods on a relatively easy asteroid, and then move onto an asteroid that has an unknown rotational period. My mentor started working with asteroid 3554 Amun that had a very small rotational period of 2.53 hours. He collected data for a whole night and also analyzed it. This is what we found.

The first plot is of the brightness (measured in magnitude) over time. Initially there appears to be a pattern that could correspond to the period of what we are looking for. But, we can’t be confident in the results. For one, the changes between consecutive images are too large. This could be very easily due to noise.

When my mentor conducted a rolling 9 measurement average, shown in the second plot, the period ended up being too short. In the end, we decided that our results are not accurate enough, and we cannot find rotational period with accuracy on our equipment. We had to give up on further plans to determine rotational period of more asteroids.

Copyright 2010: Abhimat Krishna Gautam