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Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on September 17, 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) | |
|---|---|---|---|---|---|---|---|---|
| № 8702 | N22 | E30 | 02 | 0000 | BETA | Sep 20, 1999 | Sep 27, 1999 | Oct 11, 1999 |
| № 8700 | N14 | E33 | 25 | 0140 | BETA | Sep 20, 1999 | Sep 27, 1999 | Oct 11, 1999 |
| № 8699 | N22 | W37 | 13 | 0220 | BETA | Sep 15, 1999 | Sep 22, 1999 | Oct 6, 1999 |
| № 8695 | N21 | W02 | 03 | 0030 | BETA | Sep 18, 1999 | Sep 25, 1999 | Oct 8, 1999 |
| № 8693 | N13 | W42 | 01 | 0030 | ALPHA | Sep 15, 1999 | Sep 21, 1999 | Oct 5, 1999 |
| № 8692 | S26 | W39 | 16 | 0170 | BETA | Sep 15, 1999 | Sep 22, 1999 | Oct 6, 1999 |
| № 8690 | N16 | W60 | 23 | 0440 | 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.
