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.
Although only eight observations were possible during the month, it was clear that activity during the first half of the month was much higher than the second half (which was more typical of that from previous months). The largest of seven groups seen on the 1st was AR 1640 of type Dac at 28°N/319° near the central meridian with an area of 260 millionths.
On the next observation, on the 8th, the largest of eight groups, which were evenly distributed between the northern and southern hemispheres, was AR 1652 of type Eac at 21°N/183° and area 270 millionths. The largest sunspot within this group was the leader with two small penumbral followers and a few pores in between. By the following day the leader had become quite elongated and an additional penumbral sunspot had developed in the middle of the group – the group’s size had increased slightly to 300 millionths. By the next observations on the 16th and 17th, AR 1652 had reduced to a single Hsx group approaching the western limb.
Also on the 8th an Hhx sunspot was close to the eastern limb but on the following day it could be seen that this group, AR 1654 at 7°N/147° was in fact of type Fko with a quite irregular leader and symmetrical follow. When next seen on the 16th this group was now of type Fkc with three irregular penumbral sunspots spread throughout the group – its total area was 800 millionths. By the following day, the area of the group had reduced to an estimated 470 millionths. On the 16th and 17th only three groups were seen.
The final observations on the month on the 26th, 27th and 30th showed a reduced number of groups and group sizes compared to earlier in the month.
On the 2nd only four small groups were seen, the largest being AR 1665 of type Hax at 11°N/241° with an area of 120 millionths. When next seen on the 5th it was of similar size and the other two groups seen were also in the northern hemisphere. On the 8th three northern groups were seen – again all small as the largest groups at 100 millionths each were AR 1667 of type Cso at 23°N/194° and AR 1670 of type Dai at 18°N/160°.
The next set of observations on the 17th, 18th and 19th showed an almost equal number of northern and southern groups. Again all were small in size. The largest of these, AR 1678, was initially seen as an Axx group on the 17th at 12°N/68° before disappearing on the 18th but then re-appearing on the 19th as a Dao group consisting of a bipolar group with irregular penumbral sunspot at either end of the group giving a total area of 140 millionths. Note that AR 1671 was just to the north-west of AR 1678 at 16°N/73° which was of type Cao on the 19th and area 120 millionths.
The largest of the five groups seen on the 4th, all in the southern hemisphere, were AR 1686 at 14°S/261° of type Dsc with an area of 110 millionths and AR 1683 at 17°S/202° of type Dac and an area of 120 millionths. Each of these groups consisted of three penumbral sunspots. By the 5th AR 1686 had grown slightly to 140 millionths and a few pores were also seen: this group was also nearing the western limb. AR 1683 had decayed into a Cso group with an area of 40 millionths: this group was nearing the central meridian.
The next observation on the 12th showed more activity in the northern hemisphere, with four groups compared with one in the south. The largest were AR 1696 at 4°N/92° of type Dac with an area of 190 millionths – it consisted of several small penumbral sunspots and just to its east was AR 1692 at 9°N/76° of type Hhx with an area of 240 millionths. As its type suggests it was a large symmetrical single penumbral sunspot.
Due to the poor weather conditions, the next observations were not until the end of the month on the 28th, 29th and 30th. On the 28th just three groups were seen where as five were seen on each of the following days. Of particular note were an Axx group at the high southern location of 31°S/268° (AR 1709) on the 29th only and an extended Dko group on the eastern limb at 20°S/157° (AR 1711) seen on the 30th.
AR 1711 of type Dko at 18°S/156° was the largest of four groups seen on the 1st – it had an area of 420 millionths (this group rotated around the eastern limb on 30th March). The following penumbral sunspot had reduced in size by the next day while the total area was similar. By the 6th the group was near the central meridian and how a single asymmetric penumbral sunspot of type Hkx. By the 10th it was still of a similar size, 440 millionths and now approaching the western limb. AR 1711 was seen with the protected naked eye on the 2nd, 6th and 7th. Also on the 6th a small Cao group, AR 1718, was seen at 22°N/108° (area 90 millionths) – it was of a similar form and size on the 7th but by the 10th it has developed into a complex Dao group with an area of 420 millionths: both the leading and following penumbral sunspots were quite irregular with several small umbra within each sunspot. The third largest of six groups seen on the 10th was AR 1719 of type Dao at 10°N/76° with an area of 120 millionths: this group was initially seen near the eastern limb on the 6th and an Hax sunspot before forming into a small Dac group on the 7th.
The next observation on the 20th showed an Eac group near the central meridian at 14°N/326°, AR 1726: it had an area of 150 millionths. By the following day it had grown to 400 millionths and now comprised a string of penumbral sunspots surrounded by several pores. On the 22nd the leader and middle penumbral sunspots had both become larger - although the number of penumbral sunspots had reduced, the total area of the group had increased to 500 millionths. As the group approached the western limb, its area continued to grow such that by the 24th it had an area of 670 millionths. Only the following penumbral sunspots was seen close to the limb on the 26th as an extended Hkx sunspot.
On the 25th AR 1731 had rotated onto the disk as a small Dao group at 8°N/188°. Further small penumbral sunspots had developed within the group by the following day to make the group type Esc. Further development continued such that by the 28th the group was of type Ekc and an area of 410 millionths – the group was quite complex with a particularly irregular sunspots towards the following part of the group. Further pores appeared within the group on the 29th while on the 30th a quite irregular penumbral sunspot was seen within the middle portion of the group. It was also now near the central meridian. Finally on the 29th and 30th, a Dko group was seen near the eastern limb, AR 1734 at 20°N/187°: on the 30th it comprised a pair of irregular sunspots with the follower being the more irregular.
AR 1731 at 11°N/188° was one of five groups seen on the 1st having just passed the central meridian. It was still a complex Eac type group with many small penumbral and other sunspots and a total area of 290 millionths. On the 2nd and 3rd AR 1731 was still of type Eac but it had less sunspots visible on each day such that by the 4th it was of type Cso and a single Hsx sunspot on the 5th. It was not visible on the 6th having rotated around the limb. A larger group seen on the 1st was AR 1734 at 17°S/152° with an area of 660 millionths – this was of type Dko which consisted two irregular penumbral sunspots with the following sunspot being the smaller but more irregular. As this group rotated towards the central meridian it remained type Dko but it reduced slightly such that when it crossed the meridian on the 5th it had an area of 440 millionth and it had developed several pores within the group. This group then continued to decay so that by the 9th it was just a single irregular Hkx sunspot – it was last seen close to the western limb on the 11th. AR 1734 was seen with the protected naked eye on the 7th.
On the 10th and 11th ten groups were seen, with six in the north and four in the south. The largest of these was AR 1745 which appeared on the eastern limb as an Hsx sunspot at 13°N/335° on the 10th. By the 13th it had developed into a Dkc group with an area of 390 millionths – the follower penumbral sunspot was the largest. On subsequent days the leading sunspots decayed so that by the time the group passed the central meridian on the 16th it comprised a single Hkx sunspot at 210 millionths. When next observed on the 19th it was a Hax sunspot at 170 millionths – it was last seen on the 22nd as a small Hsx sunspot close to the western limb.
By the 25th the number of groups had reduced to five – the largest being AR 1755 at 10°N/200° of type Dao and 1756 at 19°S/212° of type Dac. Both groups were of a similar size of just over 300 millionths. By the 27th AR 1755 had become type Dsi with a reduced size of 60 millionths while AR 1756 had elongated to become type Fai with a reduced size of 150 millionths. By the 31st AR 1755 must have decayed on the disk while AR 1756 was a single Hsx sunspot on the eastern limb. It was one of three groups seen on this date.
On the 13th at 17h 30m UT a very bright compact loop prominence was seen on the eastern limb – this had been the site of an X2.8 limb flare which had peaked at 16h 05m before decayed to an M1 flare by the time of the observation. The flare occurred in AR 1748 which was first seen in white light as an irregular Dko group on the following day. However a very spectacular prominence was also seen on the almost opposite limb. It comprised a hearth near the limb with several blobs and a broken jet higher above the limb up to an estimated height of 300,000 km. Just 10 minutes later only the hearth and a small jet were all that remained of this very dynamic prominence.
The largest of the three groups seen on the 1st was AR 1762 which had just passed the central meridian at 28°S/128°: it was of type Dsc with an estimated area of 130 millionths. Over the next two days the follower developed into a quite elongated asymmetrical sunspot (with the longest axis being in latitude). By the 4th all the pores between the leader and follower had disappeared while the follower continued to grow. By the 5th this group had a total area of 480 millionths. On the 7th, with the group nearing the western limb, just a single Hsx was seen. On the 5th AR 1765 developed on the disk at 8°N/51° as a small Cao group. By the 8th, with the group just passed the central meridian, it was of type Dao and area 120 millionths - it was also the only group seen on the disk.
The next observation on the 14th showed one group in the west and four others in the east (all were in the south). The western group was AR 1768 at 9°S/354° of type Dac and area 260 millionths. It was still of this type on the 16th when seen near the western limb. Two further eastern groups appeared on the 15th. Yet another southern group, AR 1775, appeared around the eastern limb on the 16th to give a total of seven groups on the disk. AR 1775 at 25°S/223° was the largest group seen on the 19th at 210 millionths as a single Hax sunspot. By the 23rd it had decayed into a small Dac group and then to type Cso on the 25th. On the 29th and 30th just three small groups were seen with two out of three being in the south (the dominant hemisphere throughout the month).
During the month activity was higher in the south than the north. Indeed on the 4th all three groups were in the south including an Fkc group, AR 1785, at 9°S/6° – it comprised a collection of irregular penumbral sunspots together with a string of pores located in the leading part of the group. By the following day many of the penumbral sunspots appeared to have merged to form a ribbon following the main penumbral sunspot. The leading pores had disappeared to make the group type Ekc. By the 6th the ribbon had broken into many penumbral parts. The shape and size of the penumbral sunspots within AR 1785 continued to change daily as the group passed the central meridian on the 8th. By the 9th fewer pores were seen and by the 11th with the group approaching the western limb, the group had decayed to an Eao type with an area of just 180 millionths. It was last seen on the 12th as a small Dso group. AR 1785 was seen with the protected naked eye on the 6th, 7th, 8th and 9th.
One of two groups seen on the 14th was an Hsx sunspot close to the eastern limb. By the following day further sunspots had rotated onto the disk to form an Esc group at 21°N/192°. When next seen on the 19th this group, AR 1793, was still of the same type with an area of 340 millionths and it had the appearance of a typical bipolar group. By the 21st with the group just pass the central meridian it had reduced in size to 120 millionths due to a contraction of both the leading and following sunspots. On the 22nd, 24th and 25th just two penumbral sunspots were seen. It was not seen on the 26th.
On the 29th and 30th six groups were seen on each date with an even spread between the north and south but all were fairly small.
Although several groups were seen on each observation during the first 10 days of the month, all were fairly small. There was also an almost equal spit between both the northern and southern hemispheres. However there was quite a spread in group latitudes for this part of the solar cycle with, on the 1st, AR 1807 at 30°N/89° (type Bxo) and AR 1811 at 6°N/7° (Axx).
On the 11th just three southern groups were seen: two of these were AR 1817 at 20°S/238° of type Dsc which comprised a few small penumbral sunspots and AR 1818 at 5°S/215° of type Dso (both had an estimated area of 140 millionths). Over subsequent days both groups developed. AR 1817 increased the number of small penumbral sunspots as it passed the central meridian on the 13th before the number of sunspot started to reduce by the 15th although its total area increased slightly to 240 millionths. As this group neared the western limb it became type Cao on the 17th and then a single Hsx sunspot when last seen on the 19th. Meanwhile AR 1818 was type Eac on the 14th with the leading and middle penumbral sunspots being the largest. It was near the central meridian on the 15th when the leading penumbral sunspot became the largest in the group when the total area was 310 millionths. The main sunspot within AR 1818 changed slightly on each of the following days while it lost all the following sunspots by the 17th – this group also became a single Hsx sunspot when last seen on the 20th.
By the 25th the number of groups seen reduced back to just three (there had been up to 8 on the 19th, 21st and 23rd). One of these was AR 1835 which was initial seen as an Hsx sunspot near the eastern limb on the 25th and 26th (at 9°S/11°). It then developed some small following sunspots on the 27th, having an area of 350 millionths on the 28th, before becoming a single irregular Hax sunspot on the 30th. By the following day this sunspot had split into two smaller more symmetrical sunspots.
Activity has reduced quite significantly compared to previous month in both the number of groups seen and their size and that some of the groups were close to the solar equator (see the Butterfly Diagram below). On the 1st the largest of three groups was AR 1835 of type Dso at 9°S/11° with an area of just 150 millionths – it consisted of two small penumbral sunspots. It was last seen close to the western limb on the 4th. On the 2nd AR 1836 at 12°N/342° was near the central meridian of type Dso with an area of 140 millionths. Although a few pores were seen around this group on the 3rd, now type Cso, it did not develop further and it was last seen as an Hsx sunspot on the 8th. This and AR 1838 were the only group seen on this date (AR 1838 was a small Cso group at 4°S/224° at 70 millionths.
On the 15th only one small Hsx group (AR 1841 at 4°S/145°) was seen while on the 18th an Hsx sunspot had appeared around the eastern limb. This group, AR 1846 at 17°S/59° had a size of 190 millionths on the 22nd (type Hax). It was seen again as an Hsx sunspot as it progressed towards the western limb and it was last seen on the 28th. The only other group seen on the 26th was AR 1850 at 11°N/33° – this was initially seen on the 20th as an Cso group before becoming type Dao on the 26th when it comprised two penumbral sunspots at either end of the group and it had an area of 140 millionths. Afterwards it started to decay to become a single Hsx sunspot on the 30th when it was close to the western limb.
This solar cycle continues to surprise with a significant increase activity during the month. This was due to both an increase in the number of groups seen and the presence of four moderately sized sunspot groups – ARs 1861, 1875, 1877 and 1884.
The first of these, AR 1861, was initially seen as an Axx sunspot near the eastern limb on the 7th. It was still just an Hsx on the 8th before becoming type Dao on the 10th at 9°S/168° with an area of 130 millionths (it comprised a leading irregular sunspot followed by several pores and a small penumbral sunspot). When the group was near the central meridian on the 12th it had grown to 290 millionths and it was of type Dkc and looking more like a typical bipolar group. By the following day many of the sunspots between the leader and follower had disappeared. On the 15th with the leader reducing in size it obtained a size of 380 millionths. The size of all sunspots had reduced when last seen on the 17th and close to the western limb although the number of sunspot had increased once again.
The 17th saw the first appearance of AR 1875 as a small Hsx sunspot on the eastern limb. When next seen a few days later on the 24th AR 1875 was just past the central meridian at 9°N/28° and of type Ekc with an area of 700 millionths. The main sunspots were at the leading and towards the following part of the group: there were many other smaller sunspots within the group. By the 25th, the leading sunspot had increased in size while the other main penumbral sunspot had decayed. Despite this the overall size of the group increased to 790 millionths and it became type Fkc. As this group neared the limb on the 28th it reverted back to type Ekc and then to type Dso when last seen on the 29th.
The 24th revealed AR 1877 at 10°S/9° of type Dkc with an area of 470 millionths through the presence of one main irregular penumbral sunspot. It was also nearing the central meridian and to the south and east of AR 1875. It was of similar appearance on the following day before it decayed to type Dao on the 28th with an area of just 190 millionths. It continued to decay to become a small Hsx sunspot close to the western limb on the 30th.
The final moderately size group was AR 1884 which was first seen on the 28th as a small Dso group at 12°S/261°. On the following day it was an Eac group with an area of 290 millionths where the latest sunspot was the follower. It has grown again such that it was 400 millionths on the 30th and now of type Ekc. This was one of seven groups seen on the 30th.
Three sunspots were seen with the protected naked eye on the 24th (2 for AR 1875 and one for AR 1877), two on the 25th (one each for AR 1875 and 1877) and one on the 28th (AR 1882 which was at 7°S/293°, of type Dko and with an area of 320 millionths).
Based on observations made up to the 19th, the increased activity seen in October continued. Of particular interest during this period were AR 1890 and 1899. The first of these groups was initially seen on 2nd as a single Hsx sunspot on the eastern limb. On the following day further irregularly shaped penumbral sunspots had rotated onto the disk – the group was at 10°S/169° and of type Ekc. It was most likely the return of AR 1861 seen in October. By the 4th AR 1890 was of similar form as on the 3rd: it comprised of several penumbral sunspots where the leader was the largest while the follower was of the greatest latitude extent. On the 5th the leader had almost split into two while more small sunspots had appeared in the middle portion of the group. The group had an estimated area of 790 millionths. When next seen on the 10th the group was still of type Ekc but it had reduced in size to 430 millionths through the decay of all but the leader sunspot. The size and complexity of the group continued to reduce by the 13th when it was seen as a small Eac group nearing the western limb. AR 1890 was seen with the protected naked eye on the 5th.
Also on the 13th an Hkx sunspot was seen near the eastern limb at 7°N/38° (AR 1899). By the 15th it was of type Dko through the presence of a small follower – the leader was the dominant sunspot which was irregularly shaped and the total area was 730 millionths. By the following day the group returned to type Hkx. AR 1899 was last seen just past the central meridian on the 19th as a much more circular penumbral sunspot with an area of 540 millionths. AR 1899 was seen with the protected naked eye on the 15th, 16th and 19th.
The recent moderately high activity continued throughout the month. The largest number of groups was ten on the 10th when the sunspot number was 128. The majority of activity was in the southern hemisphere.
The most complex of the five groups seen on the 1st was AR 1909 at 17°S/205° near the central meridian – it was a complex group of type Eac comprising several penumbral sunspots, some of which were irregularly shaped. Its total area was 360 millionths. On the next observation on the 8th AR 1909 was seen just as a single Hsx sunspot and near the western limb. Also on the 8th another complex group was seen – AR 1916 at 11°S/168°. This was of type Dac with an area of 340 millionths – the leader was the largest with many small followers some of which had penumbra. Two days later AR 1916 was nearing the limb as a collection of small penumbral sunspots – almost all the pores had disappeared.
Two groups from the 14th were seen with the protected naked eye. AR 1917 at 12°S/76° was initially seen as type Cao on the 8th near the eastern limb before becoming type Dao on the 10th and type Dac on the 14th with an area of 320 millionths. On this date it comprised of several small penumbral sunspots and pores together with a larger penumbral sunspot to the south and middle portion of the group. It was last seen on the 19th as an Hsx sunspot close to the western limb. The other naked eye group from the 14th, AR 1921, was initially seen on the 10th as an irregular Hax sunspot at 6°N/42° and near the eastern limb. By the 14th it had developed into an Hkx sunspot of area 270 millionths. By the 19th and 20th AR 1921 was seen as a close pair of penumbral sunspots due, presumably, to the splitting of the irregular penumbral sunspot.
Another complex southern group was seen just past the central meridian on the 19th – this was AR 1928 at 15°S/5° of type Eac. On the following day the leader penumbral sunspot had grown to make the group type Ekc and give a total area of 500 millionths. There were many small follower penumbral sunspots. By the 22nd the group, now nearing the western limb, was of a similar form and size although there were fewer pores.
Observations from the 25th to 28th showed either five or six small groups, all in the southern hemisphere.
Page created on 31 December 2012.