There are currently 6 sunspot groups visible on the solar disk. The most prominent groups, NOAA 2157 and 2158, are decaying. These groups still have spots of opposite magnetic polarity close to each other. A total of 7 C-class flares were recorded. The strongest flare of the period was a C3.3 peaking at 20:12UT. It occurred in an unnumbered sunspot region close to the southwest limb. NOAA 2166 is a small group embedded in a large plage area in the northeast quadrant, and produced only a C1 flare. Two filament eruptions were observed around 23:50UT and 03:40UT, but the associated CMEs were not Earth directed. Other CMEs, first observed by SOHO/LASCO on 12 September at 18:24UT and 21:48UT, were related to backside events and will not affect Earth. The proton event related to the X1 flare ended at 23:10UT. Further C-class flaring is expected, with a chance on an M-class flare. The arrival of the halo CME related to the X1 flare from 10 September was observed by SOHO/CELIAS as a shock in the solar wind on 12 September at 15:27UT. Wind speed increased abruptly from 430 to 670 km/s, and further increased to a maximum of nearly 800 km/s around 22:00UT. Bz was oriented southward between 20:30 and 22:00UT with maximum values near -17nT, then abruptly turned northward to steady values around +20 nT. The period between 21:00UT and 24:00UT was geomagnetically the most intense, with Kp reaching 7 (strong geomagnetic storm), and local K-indices at Dourbes and Potzdam reaching 6 (moderate storming). Geomagnetic conditions then quieted down, with currently unsettled to active conditions observed. Quiet to unsettled geomagnetic conditions are expected, with locally a brief active period possible in the aftermath of yesterday’s geomagnetic storm. SIDC
Over the last 24 hours, 2 M-class flares were produced by a currently unnumbered region at the northeast limb: an M2.1 flare peaking at 15:26UT, and an M1.4 flare peaking at 21:26UT. NOAA 2157 and 2158 produced 2 C-class flares each. The strongest was a C9.5 flare peaking at 02:24UT in NOAA 2157. Both of these regions have no longer a delta structure, but spots of opposite magnetic polarity are still close together. Based on the currently available imagery, no CMEs seem to have been associated to these flares. M-class flares are expected, with a chance on an X-class event. On 11 September around 23:00UT, ACE observed a shock in the solar wind. Wind speed abruptly changed from about 350 to 480 km/s. Bz oscillated between -14 and +11nT. This was the arrival of the halo CME related to the M4-flare from 9 September. The impact resulted in active geomagnetic conditions (Dourbes), while Kp reached minor geomagnetic storm levels. Also the proton flux slightly increased. The arrival of the halo CME from the X1 flare is expected for later today. Pending the orientation of the CME’s magnetic field, this may result in a major geomagnetic storm, with locally severe geomagnetic storming possible. SIDC
There are currently 9 sunspot groups visible. Only 2 low-level C-class flares were observed over the last 24 hours, both having NOAA 2157 as their source. This active region still has a delta in its main trailing spot. NOAA 2158 seems to have lost its delta structure, and has not produced any flares. The other sunspot groups are quiet. Two active regions are approaching the east limb. The greater than 10 MeV proton flux is still slightly enhanced and is currently at 1 pfu. It continues its slow decline.
C-class flares are expected, with a chance on another M-class event. Solar wind speed was mostly between 350 and 400 km/s, with Bz varying between +6 and -5 nT. Geomagnetic conditions were quiet to unsettled. Quiet to unsettled geomagnetic conditions are expected on 10 and most of 11September, possibly modulated by the high speed stream from a coronal hole that passed the central meridian on 5 September, and a glancing blow from the 6 September CME. Locally, an isolated active period is possible. Late on 11 and on 12 September, the impact of the halo CME related to the M4.5 flare from 9 September may result in active conditions and possibly a brief period of minor geomagnetic storming.
There are currently 8 sunspot groups visible. NOAA 2157 seems to be slightly declining and simplifying. NOAA 2158 developed some small spots to the west and south of the main spot. Except for the northern part, this main spot is now completely surrounded by opposite magnetic polarity flux. Both NOAA 2157 and 2158 retained their delta structures. Two C-class flares and 1 M-class flare were recorded. The strongest event was a long duration M4.5 flare peaking at 00:29UT and originating in NOAA 2158. SDO/AIA-imagery indicated post-flare coronal loops, coronal dimming and an EIT-wave. A type II radio-burst with an associated shock speed of 999 km/s was observed. The greater than 10 MeV proton flux, currently still enhanced at 2 pfu, has not increased in response to this flare (so far). The M4.5 flare was associated to a halo CME first observed by SOHO/LASCO on 9 September at 00:06UT, with a plane-of-the-sky speed around 560 km/s . The bulk of the CME is directed away from the Earth (to the northeast), but there’s still a good chance Earth will be impacted by the CME-driven shock. Estimated impact time is 12 September at 03:00UT, with an uncertainty of 12 hours. There remains a reasonable chance on an M-class flare. The warning condition for a proton event remains in effect. Solar wind speed was mostly between 350 and 450 km/s, with Bz oscillating between +5 and -5 nT. Geomagnetic conditions were quiet. Quiet to unsettled geomagnetic conditions are expected for the next three days, possibly modulated by the high speed stream from a coronal hole that passed the central meridian on 5 September. On 10 September, there’s a chance on unsettled conditions with an isolated active period in response to the possible glancing blow from the 6 September CME. On 12 September, the impact of the halo CME related to the M4.5 flare from 9 September may result in active conditions and possibly a brief period of minor geomagnetic storming. SIDC
There are currently 8 sunspot groups visible, with both NOAA 2157 and 2158 dominating the outlook of the solar disk. Five C-class flares were recorded, with the strongest a C7.8 flare peaking at 19:43UT. All C-class flares originated from active region NOAA 2157. No earth-directed CMEs were observed. The greater than 10 MeV proton flux is still enhanced, and currently at a steady 4 pfu. Both NOAA 2157 and 2158 have gained some sunspot area overnight, with magnetic delta structures prominently present. There’s still a reasonable chance on an M-class flare. The warning condition for a proton event remains in effect. On 8 September around 04:00UT, ACE observed a transient in the solar wind with wind speeds gradually increasing from a steady 340 km/s up to 430 km/s. The IMF continued pointing towards the Sun, with Bz evolving from an initial -3 nT towards its current +5 nT. Geomagnetic conditions remained quiet. Quiet to unsettled geomagnetic conditions are expected for the next three days, possibly modulated by the high speed stream from a coronal hole that passed the central meridian on 5 September. On 10 September, there’s a chance on unsettled conditions with an isolated active period in response to the possible glancing blow from the 6 September CME. SIDC
NOAA AR 2157 (Catania number 45) produced numerous C-class flares during the past 24 hours, the strongest of them being the C8.0 flare peaking today at 08:14 UT. This active region has beta-gamma-delta configuration of its photospheric magnetic field, so we expect more flaring activity up to the M-level, mostly from this sunspot group. An isolated X-class flare is possible but unlikely. The C8.0 flare was accompanied by coronal dimmings indicating the eruption of a CME. However, there is no SOHO/LASCO data yet to confirm the CME occurrence. A partial halo CME was detected yesterday first appearing in the LASCO C2 field of view at 19:24 UT. STEREO B EUVI data show that its source region was located on the far side of the Sun (filament eruption around N15E160 as seen from the Earth), so this CME will not have geomagnetic consequences. The solar proton flux is just below the SEP event threshold, so we maintain the warning condition for a proton event. Since around 04:00 UT today, the interplanetary magnetic field (IMF) magnitude is elevated (up to 12 nT) indicating the arrival of an ICME, probably corresponding to the partial halo CME detected on the Sun on September 2. Due to low solar wind speed (around 350 km/s), the geomagnetic conditions remained quiet to unsettled. The IMF now turned northward, so the geomagnetic conditions are quiet and are expected to remain so. SIDC
Eight C-class flares were produced, mainly by Catania sunspot group 45, 44 and 40 (NOAA AR 2157, 2155 and 2152 respectively). The strongest flare was a C6.7 flare, peaking at 6:54 UT on September 5, originating from Catania group 45. A partial halo CME (apparent width of about 120 degrees), with first measurement at 7:12 UT in SOHO/LASCO C2, was associated with this flare. The CME is travelling East of the Sun-Earth line with a projected plane-of-the-sky speed of 650 km/s and is notexpected to arrive at Earth. We expect flaring activity up to the M-level, in particular from the Catania groups 44 and 45 and the former NOAA AR 2139. The solar proton flux currently remains stable below the SEP event threshold. We maintain the warning condition for a proton event. The Earth is currently inside a slow (around 370 km/s) solar wind flow with average (around 5 nT) interplanetary magnetic field magnitude. The geomagnetic conditions are quiet and are expected to remain so. SIDC
Since yesterday’s bulletin, solar activity was on the C-level, with the strongest flare being the C5.2 flare peaking yesterday at 21:24 UT in the Catania sunspot group 44 (NOAA AR 1255) close to the east-south-east limb. The same active region yesterday produced the M2.5 flare that was accompanied only by a weak and narrow CME. The solar background X-ray flux is currently around the C1 level. We expect flaring activity up the M-level, in particular from the Catania sunspot group 44. The former NOAA AR 2139 (that was responsible for the major eruption on the far side of the Sun on September 1) is now appearing from behind the east limb. The solar proton flux, although increased, has stabilized below the SEP event threshold. We maintain the warning condition for a proton event. The Earth is currently inside a slow (around 390 km/s) solar wind flow with average (around 5 nT) interplanetary magnetic field magnitude. The geomagnetic conditions are quiet and are expected to remain so. SIDC
The strongest flare of the past 24 hours was the C2.6 flare peaking at 00:59 UT today in the Catania sunspot group 40 (NOAA AR 2152). This active region is growing while maintaining the beta-gamma configuration of its photospheric magnetic field. Another active region will appear during the next 24 hours from behind the east-south-east limb. It was the source of several powerful behind-the-limb CMEs yesterday. The solar background X-ray flux increased to above C1 level due to this active region. We expect flaring activity up to the M-level, primarily from the east-south-east limb and perhaps also from the Catania sunspot group 40. The long filament in the northern hemisphere is finishing its crossing of the solar central meridian. It is rising slowly, so its eruption looks imminent now. The resulting CME may be directed towards the Earth. Two partial halo CMEs were detected late yesterday evening. The first halo CME appeared at 21:36 UT in the SOHO/LASCO C2 field of view above the north-west limb, and had angular width around 165 degrees. The position of the CME source region is not entirely clear due to the data gap in the STEREO data, but the absence of CME-associated signatures in the SDO/AIA data (in the north-west quadrant around this time) indicates that the CME originated from the far side of the Sun. The second partial halo CME first appeared at 22:24 UT above the east limb and had angular width around 160 degrees. STEREO B EUVI data indicate that it was associated with a flare (probably an M-class flare) peaking at 22:15 UT in the active region just behind the east-south-east limb (as seen from the Earth). No geomagnetic consequences of these two CMEs are expected. However, the second partial halo CME (perhaps together with yesterday’s full halo CME) is most probably associated with the slow rise of the proton flux measured by GOES and ACE since late yesterday evening. We issue a warning condition for a proton event. The Earth is currently inside a slow (around 410 km/s) solar wind flow with average (around 5 nT) interplanetary magnetic field magnitude. We expect quiet geomagnetic conditions. SIDC
A handful of C-class flares were observed, with NOAA AR 2149 and AR 2152 as source regions. NOAA AR 2152 has grown in size and complexity and has developed to a beta-gamma region. More C-class flares are expected, with a slight chance for an M-class flare. No Earth-directed CMEs were visible in coronographic images. The solar wind is under influence of a coronal hole (CH) high speed stream (HSS). The solar wind speed, as observed by ACE, reached values between 400 and 450 km/s. The magnetic field is relatively stable around 6 to 7 nT, with a fluctuating Bz. Geomagnetic conditions are unsettled to active and are expected remain so for the next few hours, until quiet conditions return. SIDC