Daily Sunspot Evaluation
Observation Sheet Tuesday, 21 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)
- 3
- Number of spots (f)
- 30
- Relative number (R)
- 60
- Observer
- MA
- Reading
- all checks consistent
- File
- 19710921.jpg
Sunspot groups
| No | Group (class – spots) | B | Δ L | L | Δ Lf | U | Margin no. |
|---|---|---|---|---|---|---|---|
| 1 | D – 18 | -12 | 26W | 279 | |||
| 2 | H – 2 | 4 | 28W | 281 | |||
| 3 | D – 10 | 12 | 40W | 293 |
Class as written on the sheet (? = group the observer marked as uncertain). ⚠: the coordinates of this row do not agree with each other.