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Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on September 4, 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) | |
|---|---|---|---|---|---|---|---|---|
| № 8688 | S24 | E15 | 05 | 0010 | BETA | Sep 6, 1999 | Sep 13, 1999 | Sep 27, 1999 |
| № 8687 | N10 | W20 | 06 | 0010 | BETA | Sep 3, 1999 | Sep 10, 1999 | Sep 24, 1999 |
| № 8686 | S25 | W35 | 08 | 0020 | BETA | Sep 2, 1999 | Sep 9, 1999 | Sep 23, 1999 |
| № 8685 | S08 | E29 | 02 | 0000 | ALPHA | Sep 7, 1999 | Sep 14, 1999 | Sep 27, 1999 |
| № 8682 | N18 | W01 | 06 | 0010 | BETA | Sep 5, 1999 | Sep 12, 1999 | Sep 25, 1999 |
| № 8681 | N20 | W72 | 04 | 0120 | BETA | Aug 30, 1999 | Sep 6, 1999 | Sep 20, 1999 |
| № 8677 | N08 | W47 | 01 | 0030 | ALPHA | Sep 1, 1999 | Sep 8, 1999 | Sep 22, 1999 |
| № 8675 | N19 | W54 | 04 | 0040 | BETA | Sep 1, 1999 | Sep 8, 1999 | Sep 21, 1999 |
Solar cycle progression
The average monthly sunspot number (SSN) from January 1970 to September 1999. The gray background is the average SSN index.
