Shoemaker-Levy 9 impacts from the 0.9-meter Telescope
The Shoemaker-Levy 9 impacts on Jupiter occured July 16-22, 1994 as pieces of the object, earlier broken into a "string of pearls" by the immense gravity of Jupiter, one by one impacted Jupiter's upper atmosphere leaving scars in the visible image of Jupiter that were larger in size than the Earth. Had one of these objects hit the Earth it would have been devastating, but thankfully Jupiter had caught them and was absorbing the many blows. Observatories all over the world had plans to view the impacts if they could be seen from Earth, but no one knew if it would be possible.
At Mt. Locke, I was a staff member at the time and we made sure everything was ready for the chance to see the first impact on a foreign body, Jupiter in this case, ever observed by mankind. The 0.9-meter observer was set to look for the impact flash reflecting off one of Jupiter's moons since no one on Earth could see them directly. They would hit just over the horizon of Jupiter and within a few minutes the site would rotate into view.
On the first night, the observer was not able to see the flash as he had hoped, so his plan was abandoned freeing up the 0.9-meter for other use. No backup observations had been planned, so I asked the Superintendent for permission to do visual observations at the 0.9-meter. By the next night we were ready to take a look.
All the opportunities to view Jupiter were in the early evening, as Jupiter set shortly after sunset (and from the 0.9-meter, the mountain blocked our view of it even earlier).
We got word from the 2.7-meter Harlan J. Smith Telescope observer that the first impact of the evening had occured. We were watching the approaching edge of Jupiter anxiously to see the new impact site. When it came into view, it was incredible. As it passed over the face of Jupiter, we called just about everyone on the mountain to come take a look. Observers on the other telescopes were using guide cameras with their spectrographs which don't really produce quality images so they took turns guiding for their instruments and came to get an eye view. We viewed every night we could and had visitors from Fort Davis including the Boy Scout troop marveling at the newly formed impact "craters."
That period of viewing is my most memorable experience during my 22+ years working at the Observatory.