Phil asked me for the current longitude of the Great Red Spot. I didn't know off the top of my head.
He did some digging. "Found it on Cal Tech. 263°."
I shared that this was consistent with the setting in SkyTools 3 Pro on John Charles. 262.
Still, I finally logged into Sky and Telescopes site and ran the interactive GRS tool. It said the Jovian spot was at 259 in January. The page reminded us that the giant storm on Jupiter migrates just over 1° each month.
There I noted the link to JUPOS. Ah ha! That's what I had been thinking of.
Seems that 263 is a very good number.