Project GRAND is a cosmic ray observatory located on the University of Notre Dame campus. The observatory features a grid of sixty-four proportional wire chamber (PWC) particle detectors positioned within a 10,000 m2 field. Project GRAND was designed and built by Notre Dame professor emeritus John Poirier and his students. The observatory operated mainly between 1989 and 2011. Project GRAND detected cosmic rays from the sun and extrasolar sources. Project GRAND was also able to discern the effect of atmospheric temperature and pressure on cosmic ray surface counts.