Sunspots and active regions
The following active regions with sunspot groups were visible on the Sun on April 21, 2004. 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) | |
|---|---|---|---|---|---|---|---|---|
| № 597 | S06 | W58 | 06 | 0070 | Beta | Apr 17, 2004 | Apr 24, 2004 | May 8, 2004 |
| № 596 | S09 | E33 | 20 | 0340 | Beta | Apr 24, 2004 | May 1, 2004 | May 15, 2004 |
| № 595 | S07 | E15 | 10 | 0070 | Beta | Apr 23, 2004 | Apr 30, 2004 | May 13, 2004 |
| № 594 | N15 | W11 | 01 | 0020 | Alpha | Apr 21, 2004 | Apr 28, 2004 | May 12, 2004 |
| № 593 | S19 | W35 | 09 | 0060 | Beta | Apr 19, 2004 | Apr 26, 2004 | May 10, 2004 |
Solar cycle progression
The average monthly sunspot number (SSN) from January 1975 to April 2004. The gray background is the average SSN index.
