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M9.9 solar flare on 2021-10-28
ClassM9.9GOES-16 science data
Peak15:352021-10-28 UTC
Duration30 min
Peak flux9.9e-05W/m²
| Comparison | Value |
|---|---|
| Rank in year | 2 / 473 |
| Other M/X flares that day | 2 |
| M/X flares that month | 7 |
| Solar cycle | Cycle 25 |
Compared with the strongest flares of 2021
X1.5
M9.9
M4.7
M3.9
M2.7
M2.2
M2.0
M1.8
M1.8
M1.8
M1.7
M1.6
Other M/X flares that day
| Date | Begin | Peak | Min | Class | Location | Region |
|---|---|---|---|---|---|---|
| 07:30 | 07:40 | 14 | M1.4 | – | – | |
| 10:19 | 10:28 | 17 | M2.2 | – | – |
All times UTC. Until June 2017 classes are NOAA's reports of the time (GOES-15 and earlier included a 0.7 scaling factor); later classes come from calibrated GOES-16/18 data, so the same flare reads about 1.4× larger. Do not compare the two periods directly.
← X1.5 2021-07-03M5.5 2022-01-20 →
About this page
A M9.9 flare that began 2021-10-28 15:17 UTC; No. 2 of 473 C-class-or-larger flares in 2021.