Daily Sunspot Evaluation
Observation Sheet Friday, 21 September 1951
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)
- 5
- Number of spots (f)
- 93
- Relative number (R)
- 143
- Observer
- ET
- Reading
- all checks consistent
- File
- 19510921.jpg
Sunspot groups
| No | Group (class – spots) | r | p | Margin no. |
|---|---|---|---|---|
| 1 | E – 21 | 0.3 | 83 | |
| 2 | C – 13 | 0.54 | 110 | |
| 3 | B – 9 | 0.27 | 114 | |
| 4 | B – 11 | 0.76 | 277 | |
| 5 | E – 39 | 0.31 | 314 |
Class as written on the sheet (? = group the observer marked as uncertain). ⚠: the coordinates of this row do not agree with each other.