Suitable Great Red Spot transit times as seen from the Isle of Man: 3 Jul 2018 21:39 18.7° (Sky Bright) 5 Jul 2018 23:18 10.0° 10 Jul 2018 22:27 13.1° 15 Jul 2018 21:35 15.8° 27 Jul 2018 21:32 11.8° Calculated by Guide 9 The above transits are calculated from the GRS having a longitude (System II) of 292° on 1st June 2018. Logitude of GRS derived from data at:- http://jupos.privat.t-online.de/