Alan Chalker
Judy Gardiner


This project involves a real world application of finding comets in sun observation images from the SOHO (Solar and Heliospheric Observatory) spacecraft.

SOHO is a cooperative mission between the European Space Agency (ESA) and the National Aeronautics and Space Administration (NASA). SOHO studies the sun from deep down in its core out to 32 solar radii. The spacecraft orbits the L1 Lagrangian point. From this orbit, SOHO is able to observe the sun 24 hours a day. Even though SOHO's primary objectives relate to solar and heliospheric physics, the onboard LASCO instrument has become the most prolific comet discoverer in history!

LASCO (Large Angle Spectrometric Coronagraph) is able to take images of the solar corona by blocking the light coming directly from the Sun with an occulter disk, creating an artificial eclipse within the instrument itself. LASCO images are automatically posted on the web approximately every 20 minute. Since LASCO began taking observations in January of 1996, the C2 and C3 coronagraphs have observed over 950 new comets and 9 known comets. The vast majority of these comets were discovered by amateur astronomers who closely examine the images for potential comets. Below is a typical image recently taken by SOHO.


This project will use the MATLAB software package to develop algorithms which can automatically analyze these images for potential comets. MATLAB is a high-level programming environment very popular with scientists and engineers because of its powerful toolboxes and easy to use scripting language. Basic algorithms from the image processing toolbox will be utilized to find comets using the following general steps:

1. Load original images into MATLAB
2. Process images to isolate all bright spots and eliminate glare due to solar ejections
3. Compare spots in subsequent images to find potential comet trajectories
4. Analyze trajectories to ensure they meet known characteristics
5. Highlight possible comets in original images and create output movie

Below are subsections of a series of images which highlight an actual comet. A movie which shows this comet in motion can be seen here:

One unique perk of this project is that it is very likely new comets will be discovered by the group, in which case they will be submitted for verification to NASA and potential recognition as the finders.

     The OSC Summer Institute program is sponsored in part by: