Daily Sunspot Evaluation
Observation Sheet Friday, 17 September 1971
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)
- 7
- Number of spots (f)
- 30
- Relative number (R)
- 100
- Observer
- SM
- Reading
- all checks consistent
- File
- 19710917.jpg
Sunspot groups
| No | Group (class – spots) | B | Δ L | L | Δ Lf | U | Margin no. |
|---|---|---|---|---|---|---|---|
| 1 | C – 4 | 13 | 15E | 291 | |||
| 2 | H – 2 | 5 | 26E | 280 | |||
| 3 | A – 1 | -2 | 65E | 241 | |||
| 4 | A – 2 | -13 | 38E | 268 | |||
| 5 | E – 14 | -12 | 28E | 278 | |||
| 6 | B – 6 | -16 | 54W | 0 | |||
| 7 | J – 1 | 12 | 13W | 319 |
Class as written on the sheet (? = group the observer marked as uncertain). ⚠: the coordinates of this row do not agree with each other.