I watched Algol go through a minimum on the morning of September 20, 2017 at the Okie-Tex Star Party. There was a high haze and I could see down to 5th magnitude stars through the haze all night. I was simply amazed at how fast Algol dimmed in the height of the event. About 1/10 of a magnitude every 15 minutes.
I started my observations using 20x80 mounted binoculars, but switched to 8x50 binoculars when Perseus was directly overhead. The comparison stars were close by and I often verified my estimated magnitude naked eye.
My final observation was well into morning twilight. I tried to make one more observation at 7 am local time, but sunrise was imminent and I could not tell if Algol was identical in brightness to the 3.0 magnitude comparioson star, so I didn't record this observation.
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Finder Chart
with Comparison StarsField Notes Light Curve
