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Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on April 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) | |
|---|---|---|---|---|---|---|---|---|
| № 8517 | N20 | W23 | 04 | 0020 | BETA | Apr 16, 1999 | Apr 23, 1999 | May 7, 1999 |
| № 8516 | S20 | E42 | 08 | 0070 | BETA | Apr 21, 1999 | Apr 28, 1999 | May 12, 1999 |
| № 8515 | S16 | W33 | 09 | 0070 | BETA | Apr 16, 1999 | Apr 22, 1999 | May 6, 1999 |
| № 8514 | S32 | W49 | 03 | 0030 | BETA | Apr 14, 1999 | Apr 21, 1999 | May 6, 1999 |
| № 8513 | S18 | W46 | 02 | 0010 | ALPHA | Apr 15, 1999 | Apr 22, 1999 | May 5, 1999 |
| № 8512 | S27 | W57 | 01 | 0000 | ALPHA | Apr 14, 1999 | Apr 21, 1999 | May 5, 1999 |
Solar cycle progression
The average monthly sunspot number (SSN) from January 1970 to April 1999. The gray background is the average SSN index.
