Moderate M1.1 solar flare off eastern limb, old Region 2673 returns

Moderate M1.1 solar flare off eastern limb, old Region 2673 returns

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A moderately strong solar flare measuring M1.1 at its peak erupted at 23:28 UTC on October 20, 2017 from the vicinity of old Region 2682, numbered 2673 two rotations ago. Radio signatures suggested and coronagraph imagery confirmed, a Coronal Mass Ejection (CME) was produced by this eruption. However, due to the location of this region on the SE limb, this CME is not Earth-directed.

A Type II Radio Emission with an estimated velocity of 344 km/s was associated with the event. Type II emission occur in association with eruptions on the Sun and typically indicate a CME is associated with the flare event.

M1.1 solar flare October 20, 2017M1.1 solar flare October 20, 2017

The M1.1 solar flare on October 20, 2017. Credit: NASA SDO/AIA 131 (Helioviewer)

CME produced by M1.1 solar flare on October 20, 2017

CME produced by the M1.1 solar flare on October 20, 2017. Credit: ESA/NASA SOHO LASCO C3, NASA SDO/AIA 131 (Helioviewer)

As already mentioned, CME produced by this eruption is not Earth-directed as this region is currently located on the SE limb.

This is the same region that produced 4 X-class solar flares, including the strongest of the cycle, multiple M-class flares and CMEs and S3 - Strong solar radiation storm two rotations ago (September 2017) and it seems it still has the potential to produce powerful flares.

This region produced several CMEs on October 17th and a powerful double solar flare eruption early October 18, 2017. This suggests an uptick in solar activity can be expected over the next two weeks as the region rotates through the visible disk. 

The October 18th eruption was associated with a Type II (estimated velocity 1 443 km/s) and Type IV radio sweeps indicating a strong CME was associated with the event. In fact, there were two associated CMEs, first visible in coronagraph imagery at 05:48 UTC. 

There are currently no numbered active regions on the visible disk. Old region 2673, numbered 2682 in its previous rotation is barely visible. This will change in the days ahead.

Visible disk on October 21, 2017

Visible disk on October 21, 2017. Credit: NASA SDO/HMI. Annotation: The Watchers

Space Weather Message Code: ALTTP2
Serial Number: 1066
Issue Time: 2017 Oct 21 0027 UTC

ALERT: Type II Radio Emission
Begin Time: 2017 Oct 20 2335 UTC
Estimated Velocity: 344 km/s

NOAA Space Weather Scale descriptions can be found at

Description: Type II emissions occur in association with eruptions on the sun and typically indicate a coronal mass ejection is associated with a flare event.

Featured image: CME produced by the M1.1 solar flare on October 20, 2017. Credit: ESA/NASA SOHO LASCO C3, NASA SDO/AIA 304 (Helioviewer)

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