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Solar Highlights for June 17

Solar Rotation Nos: 2191 to 2192

A slight rise in sunspot activity but very quiet generally. More was seen in Hydrogen alpha light.

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


1st to 8th June
At the beginning of the month Active Region (AR)2661 was seen just over the east limb of the Sun. This sunspot group was just on the northern hemisphere at +6 degrees north of the solar equator and was a type Hrx sunspot. It was minor solar flare active too. By the 4th, AR2661 had grown into a type Eao sunspot. Though we did not know it, AR2661 was at its peak by then. AR2661, though still minor solar flare-active, was decaying by the 5th and by the 8th it was very hard to see and by the 9th the Sun was spotless.

9th to 12th June
No sunspots visible.

13th to 30th June
On the 13th, AR2662, a type Hsx sunspot group on the northern hemisphere, had appeared over the east limb. A light bridge was seen within AR2662 on the 19th.

AR2662 was joined on the 16th by AR2663, a type Dso sunspot, which was also north of the solar equator at +14 degrees. AR2663 suddenly appeared on the Central Meridian (the CM is the imaginary line dividing the solar disc into east and west). Surprisingly, AR2663 was starting to decay on the 17th!

AR2664 then appeared on the east limb on the 21st. This too was a northern hemisphere sunspot (at +18 degrees latitude) and was type Cso.

This was the peak of sunspot activity this month as AR2663 went over the west limb on the 23rd and was joined by AR2662 on the 26th. This left AR2664, by now a type Cao sunspot, near the CM all on its own. On the 30th AR2664 was still visible but by then nearing the west limb.

SPA Sunspot Mean Daily Frequency (MDF): 1.33 (was 1.00).
SPA Relative Sunspot Number: 17.70 (was 13.02).

Solar Prominences, Plage, Filaments and Flares

Quite an active month that is at odds with the low Prominence MDF. There were some nice hedgerow prominences to be seen with some dark filaments on the H-alpha solar disc there too on occasions.

1st to 9th June
A solar flare in AR2661 was seen by Alan Heath on the 1st. On the 3rd and 4th conspicuous areas of bright plage were seen associated with AR2661 with filaments towards the east limb. A detached prominence was seen on on the 4th at the east limb. By the 7th as AR2661 neared the CM a long twisty bright plage was seen stretching away northwards of the 3 sunspots visible at that time. A filaprom was seen on the east limb and an isolated filament was seen near the southern limb on the 7th. On the 9th despite there being no sunspot visible, an extensive area of plage and filaments were seen just west of the CM and farther south was a long dark filament.    

10th to 20th June
An extensive hedgerow prominence was seen on the NE limb on the 13th not far from AR2662. The same hedgerow (larger in extent) was still visible on the 15th. AR2662 also had some curved bright areas of plage and filaments around it.

We saw a very active solar disc from the 15th to the 19th especially around AR2662 and AR2663. Carl Bowron provided some fine images of filaments on the 19th one of which is shown above. The 18th also saw a tall broad prominence on the NE limb of the Sun.

21st to 30th June
Although at a slightly quieter level, there was plenty of prominence activity on the 22nd, particularly the north and west limbs, but there were several dark filaments on the solar disc and an especially dark one connected with AR2664 with two slightly lighter, but quite long and broad, filaments just east of AR2664.

Another filaprom was seen on the 24th on the southwest solar limb and another hedgerow prominence was seen along the NW limb on the 25th.
SPA Prominence Mean Daily Frequency (MDF): 2.90 (was 3.31).

Well done to Brian Gordon-States, who observed 29 days, and to Jonathan Shanklin and Michael Fullerton who both observed 26 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 the Director.

Images and drawings were supplied by: Carl Bowron, Mick Jenkins, Ian Lee, Cliff Meredith, Peter Paice, Julia Wilkinson and Brian Woosnam.

Geoff Elston


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