X-Flare Producing Active Regions

Sunspot Cycle 23

These are the active regions from the present solar cycle 23 (1995 - 2005) which produced X-class flares. Most have observations from the Mees Solar Observatory Imaging Vector Magnetograph (IVM), with a few from the Haleakala Stokes Polarimeter (HSP). Flares observed during Mees hours with the Mees CCD Imaging Spectrograph (MCCD) are linked through. Additional regions will be added as more events occur and more observations are analyzed.

Zirin and coworkers published two studies of the relation between great flares and sunspot magnetic configurations that provide a useful background knowledge:

  • "Delta spots and great flares" Zirin, Harold and Liggett, Margaret A. 1987. Solar Physics, Vol. 113, pp. 267-281.
  • "The Dependence of Large Flare Occurrence on the Magnetic Structure of Sunspots" Sammis, Ian; Tang, Frances and Zirin, Harold 2000. The Astrophysical Journal, Vol. 540, pp. 583-587.


    • 04-NOV-97 05:52 X2.1
    06-NOV-97 11:49 X9.4
    23-APR-98 05:35 X1.2 E Limb
    27-APR-98 08:55 X1.0
    02-MAY-98 13:31 X1.1
    06-MAY-98 07:58 X2.7 W Limb

    17-AUG-98 21:10 X1.2
    18-AUG-98 08:14 X2.8
    18-AUG-98 22:10 X4.9
    19-AUG-98 21:35 X3.9
    24-AUG-98 21:50 X1.0
    28-AUG-99 17:52 X1.1




    14-OCT-99 08:54 X1.8
    27-NOV-99 12:05 X1.4

    05-FEB-00 19:17 X1.2
    02-MAR-00 08:20 X1.1

    22-MAR-00 18:34 X1.1
    24-MAR-00 07:41 X1.8
    06-JUN-00 13:30 X1.1
    06-JUN-00 14:58 X2.3
    07-JUN-00 15:34 X1.2

    18-JUN-00 01:52 X1.0
    11-JUL-00 12:12 X1
    12-JUL-00 10:18 X1.9
    14-JUL-00 10:03 X5.7

    30-SEP-00 23:13 X1.2
    24-NOV-00 04:55 X2.0
    24-NOV-00 14:51 X2.3
    24-NOV-00 21:43 X1.8
    25-NOV-00 18:33 X1.9
    26-NOV-00 16:34 X4.0

    29-MAR-01 09:57 X1.7
    02-APR-01 10:04 X1.4
    02-APR-01 10:58 X1.1 0 (?)
    02-APR-01 21:32 X20
    03-APR-01 03:25 X1.2
    06-APR-01 19:10 X5.6
    10-APR-01 05:06 X2.3
    12-APR-01 09:39 X2.0
    15-APR-01 13:19 X14.

    23-JUN-01 04:02 X1.2
    25-AUG-01 16:23 X5.3

    24-SEP-01 09:32 X2.6
    19-OCT-01 00:47 X1.6
    19-OCT-01 16:13 X1.6

    22-OCT-01 17:44 X1.2
    25-OCT-01 14:42 X1.3
    04-NOV-01 16:03 X1.0

    25-NOV-01 09:45 X1.1
    11-DEC-01 07:58 X2.8
    13-DEC-01 14:20 X6.2

    21-APR-02 00:43 X1.5
    20-MAY-02 15:21 X2.1

    03-JUL-02 02:08 X1.5
    15-JUL-02 19:59 X3.0
    18-JUL-02 07:24 X1.8

    23-JUL-02 00:18 X4.8
    03-AUG-02 18:59 X1.0
    21-AUG-02 05:28 X1.0
    24-AUG-02 00:49 X3.1

    30-AUG-02 12:47 X1.5
    31-OCT-02 16:47 X1.2

    17-MAR-03 18:50 X1.5
    18-MAR-03 11:51 X1.5
    27-MAY-03 22:56 X1.3
    28-MAY-03 00:17 X3.6
    29-MAY-03 00:51 X1.2

    09-JUN-03 21:31 X1.7
    10-JUN-03 23:19 X1.3
    11-JUN-03 20:01 X1.6
    15-JUN-03 23:25 X1.3

    19-OCT-03 16:29 X1.1
    26-OCT-03 18:19 X1.2
    23-OCT-03 08:19 X5.4
    23-OCT-03 19:50 X1.1
    26-OCT-03 06:46 X1.2
    28-OCT-03 11:10 X18
    29-OCT-03 20:50 X11
    02-NOV-03 17:25 X8.3
    04-NOV-03 19:53 X17.4

    03-NOV-03 01:30 X2.7
    03-NOV-03 09:55 X3.9
    15-JUL-04 01:30 X1.8
    15-JUL-04 18:15 X1.6
    16-JUL-04 01:50 X1.3
    16-JUL-04 10:30 X1.0
    16-JUL-04 13:50 X3.6
    17-JUL-04 07:54 X1.0

    13-AUG-04 18:07 X1.0
    18-AUG-04 17:29 X1.8
    30-OCT-04 11:38 X1.2

    07-NOV-04 15:42 X2.0
    10-NOV-04 02:13 X2.5
    01-JAN-05 00:31 X1.7

    15-JAN-05 00:22 X1.2
    15-JAN-05 22:25 X2.6
    17-JAN-05 06:59 X3.8
    19-JAN-05 08:03 X1.3
    20-JAN-05 06:36 X7.1
    30-JUL-05 06:35 X1.3

    07-SEP-05 17:17 X17.0
    08-SEP-05 20:52 X5.4
    09-SEP-05 02:43 X1.1
    09-SEP-05 09:42 X3.6
    09-SEP-05 19:13 X6.6
    10-SEP-05 16:34 X1.1
    10-SEP-05 21:30 X2.1
    13-SEP-05 19:19 X1.5
    13-SEP-05 23:15 X1.7
    15-SEP-05 08:30 X1.1

    Regions not observed by Mees:
    27-NOV-97 12:59 X2.6 AR8113 IVM failed, no HSP or MCCD
    22-NOV-98 06:30 X3.7 0 (AR8384 AT W LIMB) IVM off, no HSP or MCCD
    22-NOV-98 16:10 X2.5 0
    23-NOV-98 06:28 X2.2 0
    24-NOV-98 02:07 X1.0 0
    28-NOV-98 04:54 X3.3 0 (AR8395?) IVM off, no HSP or MCCD
    28-DEC-01 20:02 X3.4 0 No data
    26-FEB-04 02:03 X1.1 AR10564 No data, weather
    14-JUL-05 11:29 X1.2 AR10786 No data, IVM off, weather

    The X-class flare list, gleaned from records at the Space Environment Center.

    And a beginning of a page of X flare producing regions from Cycle 22.

    Last modified: Sat Sep 17 15:47:29 EDT 2005