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Solar Highlights for February 17


Solar Rotation Nos: 2185 to 2186

A quiet month overall with a few small sunspots coming and going. There was some high-latitude aurora seen across Scandinavia (early hours of the 1st) and Alaska (the night of the 17th) Both were the result of a brisk solar wind rather than the result of sunspot activity.

Here are the solar highlights of February 2017 together with a selection of images.

1st to 9th February

The first day of the month saw a growing active region (AR)2632 along with AR2629 and AR2631. None of them were thought to be solar flare active but AR2632 looked promising as it had shown earlier signs of development. However, on the 2nd the sunspots of AR2629 had disappeared. This meant that by the 6th we had just two sunspots showing: AR2632 was nearing the west limb and AR2634 had just come over the east limb, with a blank disc in between. Both active regions had gone by the 9th leaving us with an almost blank solar disc.

10th to 19th February
AR2635 had emerged close to the central meridian (CM) on the 9th and 10th and it had showed some initial activity, but once again, this development stopped and it finally went over the west limb around the 18th. There was another active region visible, in the form of AR2636 which had emerged near the E limb on the 16th.

20th to 28th February
By now we had AR2636 near the CM and AR2637 close to the east limb. By the 21st AR2636 had gone but AR2638 had appeared over the east limb. AR2637 had gone by the 22nd leaving just AR2638 visible. The situation stayed this way until the 25th when AR2639 emerged between the CM and the west limb. Meanwhile, on the 26th there was an annular solar eclipse. This is where the Moon is unable to fully cover the disc of the Sun and at maximum eclipse a bring ring of light is seen around the Moon. This eclipse was visible only from parts of South America (Argentina, Chile) and Africa (Angola, Democratic Republic of Congo and Zambia). Some parts of South America saw a partial solar eclipse. As we arrived at the end of February, AR2640 and AR2641 appeared just east of the central meridian.

SPA Sunspot Mean Daily Frequency (MDF): 1.04 (was 1.26).
SPA Relative Sunspot Number: 13.45 (was 16.78).

Solar Prominences, Plage, Filaments and Flares

A quiet month but there were some interesting prominences along the way. A few filaments were seen.
1st to 15th February
The 1st saw plage and a small amount of filament activity around AR2629 and AR2632 as they neared the west limb. There were some interesting prominences along the SW limb on the 4th and on the east limb on the 6th. Bright plage activity was seen around and following sunspots AR2635 but only a single filament on the 12th.  There was more in the way of prominences on the 14th though most were low-lying in nature and more filaments were seen on the solar disc. 

16th to 28th February
In the second half of the month, on the 16th there were more prominences seen and a few short filaments but no sunspots or plages that day. There was a rise in prominence activity on the 20th with some lovely intricately-shaped prominences along the NE and SW limbs. The next day saw all of the prominences along the west limb but AR2638 had appeared by then and that now had plage activity around it. On the last day of February, there were fewer prominences, but no filaments. There was plenty of bright plage activity around AR2638, AR2640 and AR2641 as they crossed the northern hemisphere of the Sun.

SPA Prominence Mean Daily Frequency (MDF): 4.04 (was 4.13).

Well done to Brian Gordon-States who observed 19 days. Also to Alan Heath and Jonathan Shanklin who observed 18 and 16 days respectively.

Detailed count records of Active Regions and Relative Sunspot Numbers came from: Brian Gordon-States, Michael Fullerton, Alan Heath, Mick Jenkins, Ian Lee, Jonathan Shanklin, Bob Steele and Julia Wilkinson.

Images and drawings were supplied by: Carl Bowron, Ian Lee and Cliff Meredith.

Geoff Elston


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