AAVSO Sudden Ionospheric Disturbance Report December 1998 Observers: A-40 A-50 A-52 A-62 A-63 A-72 A-80 A-81 A-82 A-84 A-90 YYMMDD Event Peak (UT) Importance 981201 1120 1- 981201 1320 1- 981201 1814 2 981202 0910 1- 981204 1105 1- 981206 1445 1- 981207 1000 1- 981207 2155 1+ 981208 1320 2+ 981208 1407 1+ 981208 1619 1 981208 1639 2 981208 1824 2+ 981208 2018 1 981209 1745 1+ 981209 1808 1 981211 1150 1- 981211 1752 1+ 981212 1300 1 981213 0516 1- 981213 0715 1+ 981213 1035 1 981213 1852 1- 981213 2049 1- 981214 0944 2 981214 1110 1- 981214 1145 1- 981214 1220 1- 981214 1924 1- 981214 2231 1+ 981215 1055 1- 981212 2050 1+ 981216 0118 1- 981216 0958 1+ 981216 1200 1- 981216 1909 1+ 981217 0748 2 981217 1419 1+ 981217 1754 1 981217 1816 2 981217 2119 2 981217 2311 1+ 981218 0530 1- 981218 0750 2 981218 0950 1- 981218 1253 1- 981218 1540 1- 981218 1607 2 981218 1718 3+ 981219 0655 1 981219 0950 1- 981219 1435 1+ 981220 0515 2 981220 0901 2 981220 1247 1- 981221 1957 1- 981222 1527 1+ 981222 2352 1- 981223 0816 1 981223 1205 1- 981224 0656 1- 981224 1137 1+ 981224 1928 1- 981225 0622 1+ 981226 0515 1- 981226 0601 1 981226 0928 1 981226 1500 2 981226 1830 2+ 981227 0558 1- 981227 1830 2 981227 2018 1 981228 0518 1+ 981228 0546 1+ 981228 0854 1- 981228 1107 1- 981228 1200 1+ 981228 1315 1- 981228 1812 1 981228 2323 2 981229 0735 1 981229 1520 2 981229 1554 1+ 981230 0528 1- 981230 0537 2 981230 1227 1+ 981230 1810 1- 981231 0630 1 981231 0719 1 981231 1502 2+ ******************************************* Importance Summary December 1998 1- events: 35 1 events: 15 1+ events: 20 2 events: 15 2+ events: 4 3 events: 0 3+ events: 1 Total events: 90