Daily Sunspot Evaluation
Observation Sheet Thursday, 18 April 1991
There is no typed record for this day. The values below were read by computer from the table on the sheet; when in doubt, see the drawing. Details →
- Number of groups (g)
- 11
- Number of spots (f)
- 138
- Relative number (R)
- 248
- Observer
- YK
- Reading
- all checks consistent
- File
- 19910418.jpg
Sunspot groups
| No | Group (class – spots) | B | Δ L | L | Δ Lf | U | Margin no. |
|---|---|---|---|---|---|---|---|
| 1 | HK – 4 | 28 | 64W | 283 | 67W | 7.5 | |
| 2 | EKC – 72 | 8 | 21W | 240 | 24W | 13.5 | 159 |
| 3 | CAI – 20 | 13 | 07E | 212 | 04E | 6 | 169 |
| 4 | HA – 1 | -26 | 44W | 263 | 47W | 2 | 170 |
| 5 | AX – 1 | -14 | 25W | 244 | 28W | 171 | |
| 6 | BXI – 10 | -20 | 22W | 241 | 25W | 8.5 | 165 |
| 7 | AX – 2 | -27 | 10W | 229 | 13W | 0.5 | 166 |
| 8 | AX – 2 | -14 | 18E | 201 | 15E | 1 | 177 |
| 9 | DAC – 16 | -12 | 32E | 187 | 29E | 9 | 174 |
| 10 | AX – 4 | -22 | 38E | 181 | 35E | 3 | 176 |
| 11 | BXO – 6 | -8 | 38E | 181 | 35E | 7.5 | 178 |
Class as written on the sheet (? = group the observer marked as uncertain). ⚠: the coordinates of this row do not agree with each other.