Detailed Instructions: Generate a correct and concise answer for the question based on the words in the context.
Q: Context : The Oh-My-God particle was an ultra-high-energy cosmic ray (most likely a proton) detected on the evening of 15 October 1991 over Dugway Proving Ground, Utah, by the University of Utah's Fly's Eye Cosmic Ray Detector.
Question : The point in time of Oh-My-God particle was what?
A:
15 October 1991