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Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on September 28, 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) | |
|---|---|---|---|---|---|---|---|---|
| № 8710 | N19 | E66 | 01 | 0040 | ALPHA | Oct 4, 1999 | Oct 11, 1999 | Oct 25, 1999 |
| № 8708 | S11 | W07 | 04 | 0000 | BETA | Sep 28, 1999 | Oct 5, 1999 | Oct 19, 1999 |
| № 8706 | N21 | W25 | 03 | 0080 | BETA | Sep 27, 1999 | Oct 4, 1999 | Oct 18, 1999 |
| № 8704 | S19 | W65 | 01 | 0100 | ALPHA | Sep 24, 1999 | Oct 1, 1999 | Oct 15, 1999 |
Solar cycle progression
The average monthly sunspot number (SSN) from January 1970 to September 1999. The gray background is the average SSN index.