AAVSO Sudden Ionospheric Disturbance Report April 1999 Observers: A-50 A-52 A-62 A-72 A-80 A-81 A-82 A-84 A-89 A-90 YYMMDD Event Peak (UT) Importance 990402 0815 2+ 990402 1621 1- 990403 1345 1 990403 1501 1+ 990403 2053 2+ 990403 2215 1+ 990403 2310 2+ 990404 0520 1 990404 2152 1 990405 1913 1+ 990405 2311 1+ 990407 1532 1+ 990408 1315 2 990408 1722 1+ 990413 1753 2+ 990424 1917 2+ 990425 1228 1- 990427 2025 2 990428 1507 1- 990428 1905 1 990428 2033 2 990429 0830 1- 990429 1210 1 990429 1545 2 990429 1715 1 990429 1742 2+ 990429 1954 2+ 990429 2054 1+ 990430 1217 2 ******************************************* Importance Summary April 1999 1- events: 4 1 events: 6 1+ events: 7 2 events: 5 2+ events: 7 3 events: 0 3+ events: 0 Total events: 29