AAVSO Sudden Ionospheric Disturbance Report December 1999 Observers: A-09 A-50 A-52 A-62 A-63 A-72 A-81 A-83 A-84 A-87 YYMMDD Event Peak (UT) Importance 991203 1954 1- 991205 0926 1- 991207 1017 1+ 991207 1601 1 991207 2037 2+ 991208 1915 2 991209 1957 2+ 991216 0837 1 991217 0538 1+ 991217 0757 1+ 991217 0935 1 991217 1000 1 991217 1857 1- 991218 0130 1+ 991218 0430 1 991218 1705 2+ 991218 1803 2 991218 1832 1+ 991218 1910 1+ 991219 1632 1- 991221 1718 2 991222 1053 2 991222 1902 2+ 991223 0700 1 991223 1006 1- 991224 0805 2 991224 0934 2 991225 1733 2+ 991226 0850 2 991226 1142 1- 991229 0925 2+ 991231 1640 1+ 991231 1852 1+ ******************************************* Importance Summary December 1999 1- events: 6 1 events: 6 1+ events: 8 2 events: 7 2+ events: 6 3 events: 0 3+ events: 0 Total events: 33