Each month a summary of sunspot activity is written and forms part of a report sent to the Solar Section of the British Astronomical Association (BAA) and to The Astronomer. Follow the links below to read a page summary of sunspot activity. The McIntosh Sunspot Group Classification is used for sunspot group descriptions.
Activity was low during the first half of the month but increased in the second half. The only group seen on the 2nd was AR 2624 of type Bxo at 8°S/138°. It was also the only southern group seen during the month. Observations on the 4th, 5th, 6th and 8th showed spotless disks.
The next observation on the 13th showed two groups near the eastern limb: AR 2625 of type Hsx was just above the solar equator at 1°N/254° while AR 2626 of type Hax was at 8°N/242°. AR 2625 was of the same type on the 14th and 17th before becoming type Cso on the 18th with an area of 30 millionths – it was also close to close to the central meridian. By the following day it resumed being type Hax – it has decayed to type Axx on the 21st and it was not seen on the following day. Meanwhile AR 2626 had become a small Dao group by the 17th with an area of 100 millionths. It was still of this type on subsequent days before losing the smaller of the two penumbral sunspots on the 21st to become type Cso of area 30 millionths. It was of type Hsx on the 22nd and it was not seen on the 24th.
The 20th also saw the appearance on the disk of two groups, AR 2627 and 2628. AR 2627 was of type Dao and area 110 millionths at 6°N/191° having appeared since the previous day. By the 22nd it was of type Dac comprising three small penumbral sunspots and a few pores. Two days later, however, it had decayed to a loose collection of pores of type Bxo. AR 2628 was of type Cso on the 20th before becoming type Dsc on the 21st and then type Dao on the 22nd with an area of 130 millionths. By the 27th only the leader penumbral sunspot was visible. It was still of type Hsx on the last observation of the month on the 28th. Another D type group was seen on the 27th and 28th: AR 2629 at 15°N/109° which was of type Dao on the 28th and with an area of 90 millionths.
Activity was low with only 6 groups seen based on 8 observations, all being quite small. On the 7th AR 2634 was seen at 5°N/301° and type Axx. AR 2635 was seen at 12°N/303° on the 13th and 14th of type Dso at area 110 millionths on the 13th and Cso on the 14th with area 40 millionths. Futher Axx groups were seen on the 16th and 19th: AR 2636 at 11°N/183° on the 16th and AR 2637 at 5°S/123° on the 19th. No sunspots were seen on 18th. AR 2638 was of type Dso when seen close to the eastern limb on the 20th at 18°N/110° – by the 24th it has become type Cso with an area of 130 millionths with the follower pore being to the north-west of the single penumbral sunspot. Also on 24th an Axx sunspot was seen at 8°S/152°, this being AR 2639.
Activity was very low during the first three weeks of the month with no sunspots seen on 11 observations between the 4th and 21st. The first of five groups seen during the latter part of the month was AR 2643 seen on the 24th and 25th, an Axx group at 9°N/82°. On the 26th AR 2644 also developed on the disk at 12°N/54° of type Dso and area 110 millionths. By the following day the penumbral sunspots had grown slightly which continued such that by the 28th, with the group near the central meridian, AR 2644 had grown to 270 millionths. When next seen on the 31st it was of type Eao at 290 millionths but it had lost all the sunspots between the leader and follower.
On the 27th only an Axx sunspot was seen in the western hemisphere at 4°N/129° - AR 2646. On the 28th another moderately sized penumbral group had appeared on the disk in the east – this was AR 2645. It was initially seen as a Dsc group at 9°S/14° with an area of 130 millionths. By the 31st it had quickly developed into a moderately sized Eac group with many pores between the leader and follower. It has an area of 310 millionths and was visible with the protected naked eye and approaching the central meridian. Also on the 31st a Bxo group was seen to the north of AR 2645 – this being AR 2647 at 11°N/14°.
The moderate activity from the end of March continued during the first week of the month before low activity resumed for the rest of the month.
AR 2644 at 12°N/55° was seen approaching the western limb on the 1st and of type Eao with an area of 290 millionths – there were very few sunspots between the leader and follower. However, on the 2nd many more sunspots and pores were seen within the group (there had been an M5.3 flare at 08:01 UT and before the observation). Many sunspots were also seen on 4th when AR 2644 was close the western limb. The other moderately sized group from the end of March was AR 2645 at 10°S/16° – this was of type Eac on the 1st with an area of 420 millionths. The leader and follower penumbral sunspots were of approximately similar size with several smaller penumbral sunspots in between. This group was larger on the 2nd at 610 millionths and type Ekc before reducing to 500 millionths and the 3rd and 450 millionths on the 5th. On the 5th and 6th AR 2455 extended further in longitude to become type Fac. On the following part of the group was seen on the 7th close to the western limb. AR 2645 was seen with the protected naked eye on the 1st, 2nd (as two naked eye sunspots) and the 3rd.
other small groups were seen
up to 6th (AR 2659 and 2648). No
sunspots were seen on the 8th and 9th. A small group, AR 2650 was seen
on the 10th, 11th and 13th with a maximum size of 50 millionths on the
when it was of type Cso. Further
spotless disks were seen on the 15th, 16th and 17th.
Just three groups were seen during the
remainder of the month: AR 2651 at 11°N/69° between the
18th and 30th obtaining
a maximum area of 150 millionths as a Dsi group on the 24th, AR 2652 of
Axx and Bxo at 13°N/60° on the 24th and 25th and AR
2653 at 10°S/27° of type
Dso on the 24th and 25th before becoming type Hsx on the 29th and 30th
maximum size was 120 millionths on the 24th.
A detached prominence was seen on the NW limb on the 6th as was the case on the NE limb on the 11th. No particularly long or dark filaments were seen during the month. As well as plage been seen around AR 2644 and 2645, it was seen around the Bxo group AR 2648 on the 6th, 7th and 8th, around AR 2650 on the 9th, 11th and 15th and around AR 2651 on the 18th and 19th.
Activity was low during the month – although sunspots were seen on all but 3 days (based on 19 observations), all the groups seen were small in size. On the 1st the only group seen was AR 2653 as a 50 millionths Hsx sunspot at 10°S/26°. It has reduced to an Axx sunspot by the 2nd when approaching the western limb. Also on the 2nd a Bxo group has developed on the disk at 11°N/314° – AR 2654. When seen on the 5th it had become a Cso group with area 50 millionths before decaying to an Hsx sunspot on the 7th and type Axx on the 8th when close to the western limb. AR 2655 was seen at 12°N/252° on the 5th and 7th as type Csi (40 millionths) and Axx respectively. No sunspots were seen on the 12th, 13th and 14th.
Sunspots were seen again on the 16th – a single Axx at 8°S/127° approaching the central meridian (no NOAA number) and an Hsx sunspot near the eastern limb - AR 2656 at 12°N/67°. AR 2656 was seen again on the 18th through to the 21st, still of type Hsx and area 30 millionths, before decaying to type Axx on the 23rd (it was not seen on the following day). On the 19th another small Hsx developed on the disk between the 18th and 19th – AR 2658. It decayed to type Bxo on the 23rd and like AR 2656 it was not seen on the 24th. The 23rd also saw the appearance of AR 2659 near the central meridian as a Cso group at 14°N/42°. By the following day it developed several pores to become type Csi and on the 25th to type Dac with an area of 130 millionths. The leading sunspot became asymmetric from the 26th and the group grew slightly larger by the 27th to 180 millionths. It was still of type Dac on the 28th when close to the western limb.
From 8 observations between the 1st and 23rd, the few prominences seen were small with the exception of several ‘tree’ shaped prominences on the NW limb on the 23rd. The filaments seen were also fairly small. Plage was seen around AR 2654 & 2655 on the 7th and around AR 2659 and 2658 on the 23rd.
Activity remained low with no sunspots seen in the southern hemisphere, the first time this has been recorded since 2009 November. Only five different groups were observed during the month with the solar disk being spotless on the 9th, 10th and 11th.
AR 2661 was seen close to the eastern limb on the 1st at 4°N/212° as type Cso. By the 3rd it had developed into a Dac group with an area of 210 millionths, with the follower being the larger penumbral sunspot. On the 4th and 5th AR 2661 extended in longitude to become type Eac but of similar size as on the 3rd. As the group progressed towards the central meridian it lost its leading penumbral sunspots to become type Cao. It was not seen on the next observation on the 9th. An Axx sunspot was seen close to the western limb at 19°N/305° on the 5th.
The 13th revealed an Hsx sunspot close to the eastern limb at 12°N/51°. The sunspot, AR 2662 remained a single Hsx sunspot on subsequent observations obtaining a maximum size of 120 millionths on the 20th and showing several umbrae before being last seen on the 23rd as an Axx sunspot. On the 15th AR 2663 appeared on the disk approaching the central meridian as a Csi group at 13°N/94°. By the following day it became type Dso and size 60 millionths. When seen on the 18th it had decayed to type Csi – there was a string of pores following the leading penumbral sunspot. These reduced in number on the 19th to leave an Hsx sunspot nearing the western limb on the 20th and 21st.
The final group of the month, AR 2664 was initially seen as an Hsx sunspot close to eastern limb at 17°N/314° on the 20th. It remained of this type on the next few days obtaining a size of 110 millionths on the 22nd. On the 26th with the group near the central meridian, it became type Csi with several pores to the north of the penumbral sunspot. AR 2664 reverted back to type Hsx when last seen on the 30th.
Overall activity remained low with only five groups were seen but one of these was the naked eye sized AR 2665. Based on 18 observations, no sunspots were observed on the 3rd, 4th, 5th, 23rd, 26th, 27th, 29th and 31st.
On the 1st AR 2664 at 17°N/309° was nearing the western limb as type Hsx. It was last seen on the following day as type Axx. AR 2665 was first seen as a Cso group near the eastern limb on the 6th as a type Cso group and at 6°S/109° – a penumbral sunspot with a following pore. On the 7th several more sunspots could be seen following the leading penumbral sunspot which increased the longitudinal extent of the group – it was now type Eac. The leader had significantly increased in size by the following day with two umbrae within. The smaller following penumbral sunspots were quite irregular in size. AR 2665 was now of type Ekc and had an area of 550 millionths. The appearance of this group had changed again by the 10th with the leader still being irregular with a more definite main umbra. Several pores were seen between the leader and the main irregular follower. It was of a similar size as on the 8th. It was next seen just past the central meridian on the 12th, the leader was smaller with two smaller and more circular followers and other small sunspots – the total area had reduced to 410 millionths. By the 13th the follower penumbral sunspots had reduced in size but there were still many pores within the group. It was of a similar size as the previous day. AR 2665 was seen with the protected naked eye on the 8th, 10th, 12th and 13th.On the 12th AR 2665 was joined by a Cso group that developed on the disk at a similar longitude at 12°N/101° and near the central meridian. This was AR 2666. It was of the same type and size, 30 millionths, on the 13th. The only other groups seen during the month were AR 2668 on the 25th at 4°N/310° and type Axx and AR 2669 on the 30th at 16°N/254°.
From 11 observations the prominences seen were all quite small but including bright prominences seen on the western limb on the 3rd and on the north eastern limb on the 31st. The number of prominences varied from none on the 4th to six on the 31st. Several filaments were seen on each observation but none were particularly striking. A bright region of plage was seen on the eastern limb on the 5th which heralded the appearance of AR 2665 on the following day.
Activity increased slightly compared to the last few month with R being similar to that of 2017 April. The maximum number of groups seen on any observation was four while no sunspots were seen on the 14th.
On the 1st AR 2670 was seen as an Hsx sunspot close to the eastern limb. By the 4th this group, at 6°S/118°, was seen as a Dao group with the follower being the larger of the two penumbral sunspots. No other sunspots were seen within the group. By the 10th and 11th AR 2670 was of type Hkx with an area of 260 millionths on the 11th. By the 13th just a smaller Hsx sunspot was seen close to the western limb. During the period from the 1st to 13th only AR 2670 was seen.
The observation on the 15th showed a small Dai group near the eastern limb of type Dai at 11°N/303°. By the following day the complex nature of this group, AR 2671, could be seen: the group was of type Esc and area 230 millionths. By the 17th the longitudinal extent of the group increase to give a Fsc type – the larger penumbral sunspots were seen in the following part of the group. AR 2671 remained type Fac for the next few days with the group having an area of 400 millionths on the 19th and straddling the central meridian on the 20th when there were three main penumbral sunspots at the leading, middle and following positions and it extended for almost 20° in longitude. As the group progressed towards the western limb, the number of pores within the group reduced such that by the 24th the group was counted as two active areas. By the 27th only a single Hsx sunspot was seen close to the limb.
On the 20th a single Hsx sunspot was seen on the eastern limb: AR 2672. By the 22nd this group was of type Eac at 7°N/226° with an area of 360 millionths with the group comprising of four penumbral sunspots with quite a pronounced axial tilt. By the 24th AR 2672 was of type Ekx through the merging of following penumbral sunspots into a latitude extended penumbral sunspot. This reverted to small penumbral sunspots by the following day. The followers continued to decay such that on the 27th with the group just past the central meridian only pores were seen to make the group type Cai. However by the following day a small following penumbral sunspot reappeared so that AR 2672 was of type Dao with an area of 90 millionths. This group was last seen on the 31st as type Dso close to the western limb.
Three other groups were seen on the 31st: AR 2675 at 8°S/177° of type Cao and area 60 millionths, AR 2673 at 7°S/119° of type Hax and area 80 millionths and AR 2674, an impressive Fko group near the eastern limb at 16°N/104° with an area of 550 millionths. This latter group comprised two substantial asymmetrical leader and follower penumbral sunspots of similar size with a few pores in-between.Hydrogen Alpha:
The most significant prominences seen based on 8 observations were a spike prominence on the NE limb on the 18th and a combined prominence/filament on the SE limb on the 27th. All other prominences were small in size as were the filaments seen during the month. Plage was seen associated with AR 2671 on observations from the 15th, 18th, 19th, 20th, 22nd and 25th. The appearance of this plage was quite striking on the 15th when close to the limb. Plage was also seen associated with AR 2672 on the 20th, 22nd, 25th and 27th.
Activity during the first part of the month increased significantly through the presence of two naked eye sized groups.
Continuing from the end of August AR 2674 dominated on the 1st as an Fki group at 15°N/103° with a total area of 650 millionths through roughly equally sized leading and following irregular penumbral sunspots. A few pores were seen in between. A small penumbral sunspot appeared on the 2nd between the leader and follower to make the group type Fkc. The follower had decayed slightly although the area of AR 2674 was similar to the previous day. This group was of similar form on the 3rd but by the 6th, with the group just past the central meridian, it was of type Fki again with a much reduced follower which had split into two. Its longitudinal extent was 18°. On the 7th its area was 500 millionths due mainly to the leader sunspot. By the 9th no pores were seen making the two active areas due to the longitudinal separation between the former leader and follower. AR 2674 remained two single penumbral sunspots when they rotated around the limb on the 10th and 11th respectively. AR 2674 was seen with the protected naked eye on the 1st, 2nd, 3rd, 4th, 6th and 7th.
group from the end of
August was AR 2673 which was seen on the 1st as a small Hsx at
9°S/119° with an
area of 70 millionths. It was still an Hsx sunspot on the 2nd while on
several pores were seen following the small penumbral sunspot (type
next observation on the 6th showed a dramatic transformation to a Dkc
with an area of 1120 millionths! AR 2673 now comprised a very irregular
penumbral sunspot with many umbrae surrounded by a couple of smaller
sunspots. By the following day, the main sunspot has reduced in size
part to it becoming two penumbral sunspots – it was now of
type Ekc with an
area of 850 millionths. When seen on the 9th AR 2673 was near the
and was seen a collection of four penumbral sunspots surrounded by
2673 was seen with the protected naked eye on the 6th and 7th.
Eight other small groups were seen during the first 10 days of the month including AR 2680 which was on the eastern limb at 9°N/316°. It was the only group seen on observations from the 10th to 17th: it had a maximum area of 110 millionths on the 15th when of type Hax. On the 22nd AR 2681 was seen near the eastern limb of type Hsx with an area of 100 millionths at 15°S/179°. It was of similar type by the last observation of the month on the 28th. AR 2682 was on the eastern limb as an Hsx group at 11°S/124° while on the 28th it was of type Cai with an area of 170 millionth (the likely return of the active group AR 2673). The largest group on the 28th was AR 2683 at 14°N/111° which was an irregular penumbral sunspot of size 330 millionths.
A C2.0 flare was seen within AR 2674 on the 1st between 15h35m and 15h50m UT as a collection of small almost circular regions. As these began to fade, a filament formed at the following part of the flare region (SWPC/NOAA indicates that the flare started at 15h31m and ended at 15h41m UT). Plage was seen around AR 2675 on the 1st, AR 2674 on the 2nd and 9th and AR 2678 on the 10th.
There was quite a drop in activity compared to the previous month and the active area MDF and R were at their lowest since 2010 May. No sunspots were seen on the 8th, 9th, 12th, 15th and 16th.
On the 14th an Axx sunspots was seen at 8°N/320° (probably AR 2684). It is not seen on the following day. On the 21st an Hsx sunspot was seen close to the eastern limb. This was AR 2685 at 9°S/130° which was also seen on the 22nd, 25th and 27th all of type Hsx and area 60 millionths on the 25th. The only other group seen based on 10 observations was AR 2686 at 14°N/108° on the 25th and 27th. It was of type Hax on the 25th with an area of 80 millionths and type Cso on the 27th with an area of 30 millionths. AR 2686 is the third rotation of the large bipolar group seen at the end August/early September (AR 2674).
There was a further reduction in activity compared to previous months with only two active areas being observed. No sunspots were seen on 6 of the 9 observations (3rd, 5th, 6th, 10th, 13th and 19th).
AR 2687 was observed on the 17th as a Cao group at 7°S/179° with an area of 70 millionths. AR 2689 was seen near the central meridian at 13°N/108° on the 25th and 26th as a Cso group with an area of 30 millionths.
Page created on 26 December 2016.