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Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on September 18, 1999. Coordinates are given as of the end of the day.
| Group ID | Location | Number of sunspots | Area (msh) | Type | CM Passage | Disappearance (W90) | Reappearance (W270) | |
|---|---|---|---|---|---|---|---|---|
| № 8704 | S21 | E63 | 01 | 0070 | ALPHA | Sep 24, 1999 | Oct 1, 1999 | Oct 15, 1999 |
| № 8703 | N21 | W92 | 01 | 0000 | ALPHA | Sep 12, 1999 | Sep 19, 1999 | Oct 3, 1999 |
| № 8700 | N13 | E20 | 30 | 0170 | BETA | Sep 21, 1999 | Sep 27, 1999 | Oct 11, 1999 |
| № 8699 | N22 | W52 | 09 | 0170 | BETA | Sep 15, 1999 | Sep 22, 1999 | Oct 6, 1999 |
| № 8695 | N21 | W16 | 01 | 0020 | ALPHA | Sep 18, 1999 | Sep 25, 1999 | Oct 8, 1999 |
| № 8693 | N12 | W56 | 01 | 0020 | ALPHA | Sep 15, 1999 | Sep 22, 1999 | Oct 5, 1999 |
| № 8692 | S25 | W53 | 08 | 0170 | BETA | Sep 15, 1999 | Sep 22, 1999 | Oct 6, 1999 |
| № 8690 | N16 | W74 | 13 | 0310 | BETA | Sep 13, 1999 | Sep 20, 1999 | Oct 4, 1999 |
Solar cycle progression
The average monthly sunspot number (SSN) from January 1970 to September 1999. The gray background is the average SSN index.
