Author Archives: sponli

The Sun Online and solar activity. September 4, 2014

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

Equipment: Coronado 90 +  Imaging Source DMK  + LX75
Processing: Photoshop, Avistack 300 frames
Date: 09/04/14
Time UT: 16:00
Exposure 1/500 sec.

Observatory Sponli

  

The Sun Online and solar activity. September 3, 2014

A partial halo CME was detected yesterday in association with the eruption of a long filament in the northern hemisphere. The CME first appeared in the SOHO/LASCO C2 field of view at 16:36 UT, had angular width around 190 degrees and the projected plane-of-the-sky speed around 450 km/s. Despite
the position of the CME source region not far from the solar disk center, the bulk of the CME material went northward of the ecliptic plane. The arrival of the corresponding ICME and even of the ICME-driven shock at the Earth is unlikely, so no resulting geomagnetic disturbance is expected. This CME is a far side event as seen from Venus, so it will not affect Venus either.
SIDC

Equipment: Coronado 90 +  Imaging Source DMK  + LX75
Processing: Photoshop, Avistack 300 frames
Date: 09/03/14
Time UT: 16:00
Exposure 1/500 sec.

Observatory Sponli

  

The Sun Online and solar activity. September 2, 2014

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

Equipment: Coronado 90 +  Imaging Source DMK  + LX75
Processing: Photoshop, Avistack 300 frames
Date: 09/02/14
Time UT: 16:00
Exposure 1/500 sec.

Observatory Sponli

  

The Sun Online and solar activity. September 1, 2014

Two partial halo CMEs were detected today, first appearing in the SOHO/LASCO C2 field of view at 00:36 and 09:24 UT respectively. Their angular widths were similar (around 150 and 130 degrees respectively), as well as were their shapes, although the first one was significantly weaker than the second one. Both CMEs seem to result from activity in the active region on the far side of the Sun (around N10W130) as observed by STEREO/EUVI, so none of them is expected to arrive at the Earth.
SIDC

Equipment: Coronado 90 +  Imaging Source DMK  + LX75
Processing: Photoshop, Avistack 300 frames
Date: 09/01/14
Time UT: 16:00
Exposure 1/500 sec.

Observatory Sponli

  

The Sun Online and solar activity. August 31, 2014

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

Equipment: Coronado 90 +  Imaging Source DMK  + LX75
Processing: Photoshop, Avistack 300 frames
Date: 08/31/14
Time UT: 16:00
Exposure 1/500 sec.

Observatory Sponli

  

The Sun Online and solar activity. August 30, 2014

The Sun produced several small C-class flares, originating from NOAA AR 2146, AR 2149 and AR 2152. AR 2146 has now rotated around the West limb. No Earth-directed CMEs were detected. More C-class flares are expected, with a slight chance for M-class flares. Solar wind speed values ranges between 400 and 450 km/s. The magnitude of the interplanetary magnetic field remained relatively stable around 6 to 7 nT, while Bz is fluctuating between -6 and +6 nT. Geomagnetic conditions are unsettled to active and are expected remain so for the next 48 hours, due to the influence of the increased solar wind related to the equatorial coronal hole.
SIDC

 

The Sun Online and solar activity. August 29, 2014

A halo CME was observed in SOHO/LASCO C2 and STEREO B/COR2 imagery, with first measurements at 17:36 UT and 17:54 UT on August 28 respectively. The apparent width is estimated to be 210 degrees. This CME is related to a backsided event and as such is not Earth directed.
SIDC

 

The Sun Online and solar activity. August 28, 2014

Only two small C-class flares were observed in the past period. All active regions at the frontside are relatively stable. No Earth directed CMEs were observed. Flaring activity is expected to remain at the level of C-flares. A equatorial coronal hole has crossed the central meridian, which is likely to influence the solar wind conditions near Earth starting on August 30.The magnitude of the interplanetary magnetic field declined from 15 to 9 nT, with Bz mainly being southward. The solar wind speed is fluctuating between 300 and 380 km/s.
Geomagnetic activity reached active levels (local K=4 at Dourbes), with even an single time slot of minor storm level (NOAA Kp=5). A return to quiet to unsettled conditions is expected, till the potential arrival of a shock related to the August 25 CMEs later today.
SIDC

 

The Sun Online and solar activity. August 27, 2014

Solar activity has decreased in the past 24 hours. Only a few C-class flares were observed, with NOAA ARs 2146, 2149 and 2151 as source regions. The largest flare was a C5.6 flare, peaking at 23:25 UT on August 26. No Earth-directed CMEs were observed. Flaring activity is expected to continue at the level of C-flares, with a slight chance for an isolated M-class flare. The risk for a proton event has reduced, but for the time being we leave the warning condition due to position of AR 2146 which still has a delta component.Solar wind observations indicate the arrival of an ICME around 0:00 UT of August 27, related to the CMEs of August 22. The magnitude of the magnetic field has smoothly increased from about 5 to 15 nT. The Bz component is southward with values up to -14 nT. Solar wind speed increased from 280 to 320 km/s, while there were only small variations in density and temperature.  Geomagnetic conditions are currently unsettled (local K at Dourbes=3) to active (NOAA Kp=4), which is expect to persist for the next few hours, till quiet conditions return. The potential arrival of the August 25 CMEs might cause active conditions again from the UT afternoon of August 28 onwards.
SIDC

 

The Sun Online and solar activity. August 26, 2014

Flaring activity continued at the same level with four C- and two M-class flares, originating from NOAA AR 2146. Two CMEs were observed in coronographic imagery, with NOAA AR 2146 as source region.
An asymmetric halo CME was visible in SOHO/LASCO C2 and C3 and STEREO B/COR2 data, with first measurements on August 25 at 15:24 UT (C2), 16:18 UT (C3) and 16:24 UT (STEREO B)  respectively. The CME was associated with a M2 flare peaking at 15:11 UT, dimming and type II and IV
radio bursts (shock speed estimated at 707 km/s by the Sagamore Hill station). The CME has a projected line-of-sight speed of 568 km/s (CACTus estimate). A second partial halo CME was visible in SOHO/LASCO C2 and C3, with first measurements on August 25 at 20:36 UT (C2) and 21:18 UT (C3). Also this CME was associated with an M-class flare (M3.9, peak at 20:21 UT). The CME is travelling with a projected line-of-sight speed of 761 km/s (CACTus estimate).
Both CMEs are mainly propagating in the western direction from the Sun-Earth line and might be interacting with each other. A shock might arrive in the second half of the UT day of August 28.  
More C- and M-class flares are expected, especially from NOAA ARs 2146 and 2149. An X-class flare is possible, but unlikely. Proton flux levels at > 10MeV have increased from 18:00 UT on, but remained
below the event threshold and are currently decreasing. A warning condition for a proton event, in case of more flaring, is issued. Solar wind speed slightly increased from 250 till 290 km/s. The amplitude of the
interplanetary magnetic field increased to 7 nT, with a varying Bz component. Geomagnetic conditions were quiet to unsettled and are expected to remain so until the combined arrival of the August 22 CME’s. This may potentially result in active geomagnetic conditions from the afternoon of August 26 onwards.
SIDC