These predictions assume the Red Spot is at Jovian System II longitude 80°, the
most recent value provided by John W. McAnally of the Association
of Lunar and Planetary Observers. If it has moved elsewhere, it will transit
1 2/3 minutes late for every 1° of longitude greater than 80° or 1 2/3 minutes
early for every 1° less than 80°.
Markings on Jupiter appear closer to the
central meridian than to the limb — and thus well placed for viewing — for
50 minutes before and after their transit times.
(subtract 5 hours to get EST)
