Without trying to sound the alarms, I was imaging Jupiter around sunset this evening and found that there is an unusual dark spot in the northern hemisphere. Here are the multispectral images. More as I learn the source of the image (we won’t start talking about possible impacts until others have confirmed the dark spot, and given how bad the seeing was this evening I’m not jumping to any conclusions.)
UPDATE: Further observations by observers in Asia on subsequent rotations did not identify any corresponding anomaly to the one shown above. My conclusion is that the spot was caused by a local, transient phenomena that affected the data and was not an actual feature on Jupiter. Most likely, the spot was caused by condensation on a dust mote on the sensor that gradually dissipated, as it did not appear on flat-frame (calibration) images taken later in the evening in an attempt to identify the source of the spot.