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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.
Throughout the month, activity was predominantly in the southern hemisphere. This was the case on the 4th when one group was seen in the north and four in the south. All of these groups were either small or moderately sized - the largest was a Dac group at 18°S/296° with an area of 190 millionths. Another Dac group seen on the 4th, at 6°S/220°, had increased in size from 110 millionths to 230 millionths by the 6th when it was nearing the central meridian. It included several small penumbral spots with the largest spot being at the following location. By the 9th, the appearance of this group had changed such that the largest spot was now the leading spot. There were now many following spots. This group had a similar appearance on the 11th but by the 12th, just a few spots were seen when the group was near to the western limb. Another group that included many small spots was first seen on the 6th as an Axx spot close to the eastern limb. By the 9th, this group, at 15°S/151°, had developed into a Dac group with an area of 410 millionths. There were many small penumbral spots spread throughout the group. Most of these spots had decayed by the 11th such that the groups total area had reduced to 180 millionths. The group continued to decay to 120 millionths on the 12th and to an Axx group on the 16th. On the 16th, more northern groups were seen while the six southern groups seen were of either type A or H. For the remainder of the month, none of the groups seen were particularly large - the largest being an Esc group at 19°S/346° on the 24th with a total area of 180 millionths. Also the southern hemisphere resumed its dominance over the northern hemisphere.
On the first two days of the month the majority of the activity was in the southern hemisphere - the largest group on the 1st was an Hsx group at 6°S/224° with an area of 120 millionths. Close to the eastern limb on the 1st was a Dso group. By the 2nd, more spots from this group, at 14°S/160° , had rotated onto the disk to give the group a classification of Eac. By the time of the next observation, on the 13th, this group consisted of just two small penumbral spots. This group was last seen on the 14th close to the western limb. All the other six groups seen on the 13th were all small in size; these were predominately in the western hemisphere. One of these groups, of type Axx, was close to the equator at 1°N/108° . The number of groups reduced such that only 3 were seen on the 16th (all type Axx) and just one northern group on the 17th at 13°N/346° of type Dao with 3 spots and a total area of 70 millionths. As this group progressed across the disk as a single Hsx spot, another group accompanied it to its north-east. This latter group became the largest seen during the month. On the 18th it was a single Axx spot while on the 19th it was a Dai group at 18°N/333° with an area of 100 millionths. It continued to grow in size such that by the 22nd it was of type Eac straddling the central meridian with an area of 310 millionths. The area of the group was split between the leading and following parts of the group although the leader consisted of one spot and the follower of two penumbral spots. As this group progressed towards the western limb it decayed such that by the 25th the following penumbral spots had disappeared. On the 26th just three spots were seen including the leading penumbral spot. During the period 16th to 26th, there were few southern group; indeed no southern spots were seen on the 17th, 18th, 19th, 23rd and 24th.
The dominant group at the start of the month was at 11°N/172° which was seen as a type Dkc group on the 2nd with an area of 490 millionths. The largest spot of this group was the leader. By the 6th, with this group on the central meridian, there was just one penumbral follower. The area of the group had reduced slightly to 420 millionths. When next seen on the 9th, the main spot had lost it attendant penumbral spots and it became symmetrical and thus it was of type Hhx with an area of 310 millionths. Another Hhx spot was seen on the 9th, this time near to the eastern limb at 6°N/80° with an area of 400 millionths. When next seen on the 14th, the spot had become asymmetric with a second umbra in the northern part of the spot and its size had increased to 540 millionths. The group had grown to 640 millionths by the 15th and as the group neared the western limb on the 18th, a separate penumbral spot was seen to the north of the main spot. During the period from the 14th to 18th, a southern group, at 14°S/60° grew from 60 to 530 millionths: on the 14th it was of type Dac, on the 15th and 16th of type Dai, on the 17th and 18th of type Eac. On the 18th, the largest spot was in the middle of the group which included several umbrae. Between the 14th and 16th a high latitude group was seen at 32°N/74°, which on the 14th was of type Dsc with an area of 70 millionths. On the 2 other dates, it had an area of just 40 millionths. The third group seen on the 18th was an Axx spot towards the eastern limb at 11°S/305°. This was the only spot seen on the 21st and 22nd! Additional groups began to appear on the eastern side of the disk and around the eastern limb from the 23rd onwards. The largest of these was initially seen as type Cso at 14°N/252°. By the 26th, it had become type Dsc with an area of 60 millionths but by the following day it was of type Dkc with an area of 310 millionths. The group was now nearing the central meridian and it had an asymmetric leader and follower spots, each with several umbrae. By the 30th, the leader spot had become symmetric and many of the following spot had disappeared - it now had an area of 230 millionths. The decay continued such that on the 31st the group was of type Cso with an area of 180 millionths. The Hhx spot seen on the 9th returned on the 30th, still of the same type and with a similar area of 270 millionths (at 13°N/170°). A few attendant spots were seen on the 31st.
The largest group seen on the 2nd was at 13°N/168° and of type Cko with an area of 310 millionths. It comprised of an irregular penumbral spot with several umbrae and a small spot in the leading position. On the 4th just an Hkx spot was seen while on the 5th, this spot had reduced in size to 230 millionths to give the group a classification of Hax. As the group progressed towards the western limb, it was still of type Hax and it was last seen on the 8th. Another single penumbral spot was seen near the eastern limb on the 4th: it was at 7°N/83° and of type Hhx and it was the only group in the eastern hemisphere. As the spot moved away from the limb, its area increased to 400 millionths on the 7th when it was of type Hkx. Between the 6th and 13th, several attendant spots were seen close by. The spot was last seen on the 15th near the western limb. During the early part of the month, an Eac group was seen on the 4th and 5th at 12°S/191°. This group was first seen as type Dsi on the 2nd with an area of 70 millionths. This had increased to size to 340 millionths on the 4th when there were several penumbral spots spread throughout the group with the largest spot being the following one. By the next day the group had reduced in size to 230 millionths. This decay continued as the group neared the western limb. Between the 15th and 18th, the number and size of groups reduced significantly such that on the 16th and 17th, no northern spots were seen and there was only one penumbral spot in the south. From the 18th, additional groups appeared around the eastern limb. One of these was first seen on the 19th as type Dko at 13°S/239°. By the 21st, it had an area of 380 millionths, with the majority of its area being in the leading penumbral spot which was quite elongated in latitude. Subsequent observations showed the group reducing in size such that on the 26th, it was of type Hax with an area of 150 millionths. It was last seen on the 29th being of type Cao with an area of 100 millionths. On the 26th a Dac group at 16°N/202° was seen with an area of 320 millionths. This group comprised of two almost equally sized penumbral spots at either end of the group and with several spot in between. Nothing was seen at this location on the 23rd. By the 29th, the following spot had reduced in size to give an overall reduced area of 290 millionths. Another rapidly developing group was initially seen as an Axx spot on the 26th and then as an Ekc group with an area of 490 millionths on the 29th! This group, at 12°S/154°, comprised of many penumbral spots and it was the largest group seen during the month.
The Ekc group at 12°S/154° seen on the 29th April had more than doubled in size by the 4th when it had an area of 1120 millionths. The group was still of type Ekc with the largest spot being the leader which had several umbrae; several other smaller penumbral spots followed, including one in the middle of the group which appeared to include a region of photosphere. By the following day this middle penumbral spot had disappeared completely to leave a few small spots. The total area had reduced to 800 millionths. The group decayed further as it approached the western limb on the 6th and 7th. The high latitude Bxo group from the 29th April had developed into type Fac by the 4th at 33°S/148° with an area of 190 millionths. Its size was slightly larger on the 5th at 390 millionths. The following part of this group was last seen on the 8th. After these two groups had rotated off the disk, activity was quite low with no southern groups seen on the 9th and 10th and no northern groups on the 19th and 25th (although one northern group was seen on the 24th). Between the observations on the 24th and 25th, a Dac group had developed on the disk at 6°S/182° with an area of 180 millionths. Both of the penumbral spots were irregular, especially the leader which was just to the north of the other penumbral spots. On the 26th, with the group near the central meridian, it had not changed in size but its appearance had. Now there were many small penumbral spots in a compact cluster. When next seen on the 28th, the group had increased in size considerably to 750 millionths and type Dkc when it comprised of one main penumbral spot with many umbrae as well as a region of photosphere. Over the next 2 days, the group continued to grow with an area of 800 millionths on the 29th and 1060 millionths on the 30th but it was still of type Dkc on both dates. Between the 24th and 30th, another high latitude group was seen. This was of type Hsx at 31°S/156° on the 24th. It was still of this type on the 25th and 26th before the single penumbral spot began to split into two on the 30th. The longitude of this group reduced by about 6° during the period it was observed due to differential rotation.
The dominant group seen during the month was just a Dac group at 13°N/23° and near the eastern limb on the 2nd. Its area was estimated to be 380 millionths on the 3rd when it consisted of just three asymmetrical penumbral spots. On the 4th and 5th small spots, some having penumbra, appeared around the main spots. The area of the group remained roughly the same. But on the 6th, larger penumbral spots had developed to give the group a classification of Dkc with an area of 550 millionths. On subsequent days, the group continued to grow, especially in the following part of the group. By the 11th, with the group nearing the western limb, the estimated area was 1040 millionths with many more penumbral spots towards the leading part of the group such that it was now of type Fkc. The following part of the group was seen near the western limb on the 13th as the leading part had already rotated off the disk. This group appears to have returned around the eastern limb on the 29th as an Ekc group at 12°N/36° with an area of 710 millionths. The other prominent group of the month was initially seen near the eastern limb on the 7th as an elongated asymmetric spot and a smaller leading penumbral spot. This group, at 15°S/309° had its largest estimated area on the 9th at 760 millionths when the group was of type Ekc. By the 11th, the northern part of the main spot had decayed but many smaller spots were seen at the leading and following parts of the group when it had an area of 480 millionths. As the group progressed towards the central meridian, the main spot decayed which continued as it moved towards the western limb along with a reduction in the number and size of surrounding spots. By the 16th, it was of type Dac with an area of 120 millionths while on the 18th, it was just an Hsx spot near the western limb. The return of the large group from the end of May was seen on the 16th to 21st at 5°S/188° but much reduced in size at, for example, 280 millionths and type Dkc on the 20th.
On the 6th, the moderately large sunspot group seen at the end of June was the dominant group of the 3 seen. At 14°N/31° it was now of type Fkc but with a similar area of 730 millionths. The main spot of the group was the leader with several penumbral follower spots. On the 7th, several additional small spots could be seen within the group. By the 9th, the group was nearing the western limb and consequently the group appeared smaller. On the 10th, only two penumbral spots from the following part of the group could be seen close to the limb. During the 2nd week of the month, several groups developed on the disk and rotated onto the disk. On the 15th and 16th 10 groups were seen which were roughly evenly split between the northern and southern hemispheres. The largest of these was initially seen as a Hax spot on the eastern limb on the 13th. By the 14th, it was of type Hkx but by the 15th a couple of following penumbral spots had developed to give an area of 580 millionths to this Dkc group at 15°N/191°. The leading spot appeared to have formed by the merger of two penumbral spots. This group had a slightly smaller area on the 16th at 420 millionths mainly through a reduction in the size of the main leader spot. By the 19th however, just a single penumbral spot together with several small spots at the leading and following positions were seen. Now the total area had reduced to just 70 millionths. On the following day, many of the small spots had disappeared. Between the 16th and 19th, a Dso group at 10°S/196° had developed into a Dkc group with an area increase from 70 to 440 millionths. On the 19th, the group comprised many penumbral spots spread throughout the group while on the 20th many of these had merged, especially in the middle of the group. Now the total area had increased slightly to 560 millionths. Observations made on the 27th and 28th showed a much less active disk with only small groups present.
The most prominent group from the start of the month was first seen on the 2nd as type Esc close to the eastern limb at 16°S/293°. On the 3rd, the group comprised leading and following penumbral spots with a few small spot in between. The largest spot was the leader. By the 4th, the group was now classified as type Ekc with an area of 790 millionths. As the group neared the central meridian, the two main spots appeared more asymmetric with the leader becoming much larger than the follower even though the total area remained fairly constant up to the 8th. On the 8th the leader spot had decayed into two penumbral spots and the total area reduced to 590 millionths. During the period 2nd to 8th, the southern hemisphere was the more dominant such that on the 8th the northern hemisphere was spot less. Two observations at the end of the month, on the 30th and 31st, showed only small groups spread evenly between the northern and southern hemispheres.
Activity at the start of the month was quite low in terms of the size of groups seen: the largest was a Dac group on the 5th at 21°S/323° which had an area of 290 millionths when the group was nearing the western limb. No spots were seen in the northern hemisphere on the 5th, 6th, 8th, 9th and 11th to 14th. Activity in the southern hemisphere was also quite low with just one group seen on the 8th and 9th. On these two dates, this group was of type Csi. By the 11th, it had developed into type Dac at 7°S/221° which consisted of several small penumbral spots. On the 13th its total area had increased to 320 millionths as the group now comprised of a string of small penumbral spots. One remaining penumbral spot was seen on the western limb on the 15th. A northern Bxo group had formed on the disk on the 16th at 14°N/161°. By the following day it had developed into a Dac group with an area of 200 millionths. Although the size of the group did not increase substantially before it passed around the western limb, it did become type Esc when last seen on the 19th. The 20th saw the arrival around the eastern limb of what was to become the largest group of the month. This was initially an Hhx spot and then on the 21st an Eko group and on the 22nd an Eki group at 4°N/357° with an area of 460 millionths. On this date, the group comprised of a main leading penumbral spot, two follower penumbral spots with a few spots in between. The size of the group increased further over the next two days to 620 millionths and of type Fkc on the 24th. Now the leader spot had increased in size and became more asymmetric while the follower had also increased in size. By the 27th, the leader spot had decayed into several smaller penumbral spots. The follower spot had also reduced in size, but there were many more spots throughout the group. It was now of type Fac with a reduced area of 500 millionths.
White light activity was quite remarkable during the latter part of the month due to the presence of three large sunspot groups. One of these groups was the largest during the current solar cycle. This substantial increase in activity was preceded by a period of particularly low activity. For example, the sunspot number was just 12 on the 13th but 183 on the 30th! The observation on the 5th showed a southern Fsc group at 6°S/230° crossing the central meridian with a longitudinal extent of 22° but with an area of just 270 millionths. The size of all the penumbral spots were small and there was many small spots spread throughout the group. By the 11th this group was nearing the western limb but with fewer spots. During the period 13th to 17th, there were very few groups and spots seen; on the 13th and 15th just one group was seen. On the 18th, a group appeared around the eastern limb which was to become the first of the three large groups of the month. On this date it comprised of three penumbral spots at 6°N/356° and it was the return of the F type group last seen at the end of September. When next seen on the 20th, the group consisted of two irregularly shaped penumbral spots, with the northern one being the larger to give a total group area of 940 millionths. By the 23rd these two penumbral spots had coalesced and enlarged to give a complex spot with many umbrae; its area was now 1610 millionths and the group was of type Ekc. When seen on the following day, an area of photosphere was seen within the group and its size had reduced slightly to 1380 millionths. As the group neared the western limb it began to decay such that on the 26th and 27th it was of type Dkc and on the 27th it has an area of 1080 millionth. It was last seen close to the solar limb on the 30th. The second of the large groups was seen near the eastern limb on the 23rd as an Ekc group at 17°S/286° comprising of an extended irregular penumbral spot close to the limb and a smaller leading penumbral spot. By the following day it could be seen that the larger spot was going to be quite impressive as it rotated further towards the centre of the disk. On the 25th the group had reached type Fkc with an area of 2300 millionths. The largest spot was quite irregular with a finger of photosphere stretching towards its middle and with several umbrae within it. A few smaller penumbral spots were seen at the following part of the group. When seen on the 26th, the smaller leading penumbral spot had split into two while the main spot occupied a region about 10° in longitude and 8° in latitude; it was still very irregular with a region of photosphere within the penumbra. On the 27th the main spot had changed shape slightly but there were now many more small spots within the group and especially in the leading position. When next seen on the 30th, the group had grown slightly to 2380 millionths. The largest spot was now towards the following part of the group through the development of several new small leading penumbral spots. This main spot had changed shape from the 27th still with many umbrae and a region of photosphere within it. By the following day, this region had rejoined the rest of the photosphere and this spot had reduced in size to give a total area of 2090 millionths. The third large group developed on the disk slightly to the west of the previous large group but in the northern latitude at 9°N/292°. It was first seen on the 27th as a curious oval shaped string of penumbral spots about 6° in longitude and 4° in latitude (the middle of the oval was devoid of spots). It was assessed to be of type Dkc with an area of 240 millionths. It had developed rapidly as nothing was seen at its location on the previous day. On the 28th, it was seen with the protected naked eye (along with the above two large groups). When next seen on the 30th, it had become a Fkc group with an area of 1570 millionths. It now comprised two nearby irregular penumbral spots and a few surrounding spots. The leading main penumbral spot had a large umbra while the main following spot had many umbrae. On the 31st the two large penumbral spots had merged. Now the group had a total area of 2040 millionths.
After the large sunspot group at 17°S/286° had rotated off the disk on the 4th, activity was quite low during the first half of the month. On the 5th and 6th, no spots were seen in the north and just one group in the south. This group, at 22°S/243°, passed around the western limb on the 7th to leave a blank disk. Further observations on the 14th, 15th and 16th showed no southern groups but the first of the large October groups was seen near the eastern limb. It was of type Dac at 4°N/3° on the 16th with an area of just 270 millionths. The next observation on the 24th showed that this group had reduced in size again to leave a small Hsx spot approaching the western limb. The observation of the 24th showed the return of the other two large October groups. Both had substantially reduced in size. Now the larger of the two was the northern one at 9°N/295° with an area of 580 millionths and it was of type Dki. It comprised one main irregularly shaped leading penumbral spot with several umbra within it and a much smaller following penumbral spot. On the 27th and 28th, it had reduced slightly to 430 millionths with the leading spot being of a different shape on the two dates. It was last seen on the 30th near the western limb. The southern group, which had been the largest group of this solar cycle, had become a collection of four small irregularly shaped penumbral spots and a few surrounding spots with a total area of just 250 millionths. It was at 18°S/283° and of type Dac. This group had reduced in size again by the 27th to just 160 millionths. The number of spots within the group had reduced by the 30th and the group was now nearing the western limb. These two groups were seen with the protected naked eye on the 24th. During the latter part of the month, there were several other groups present: for example on the 30th, there were a total of 11 groups on the disk.
The largest of the four groups seen on the 5th was of type Dac at 6°S/140° with an area of just 210 millionths: it was the furthest east of all the groups. Subsequent observations on the 7th and 8th showed no new groups and just three groups on the disk. On the 15th and 16th, two groups were seen near the middle of the disk. But on the 17th, five groups had appeared three of them near the eastern limb but all were fairly small. On the 18th, an Hsx spot was seen near the eastern limb. This became the leading spot of a Fac group seen on the 21st at 10°N/260° with an area of 350 millionths. By the 27th, the following part of the group had increased in size such that on the 28th it had a total area of 570 millionths. The following part of the group was seen on the western limb on the 31st (along with a Bxo group towards the eastern limb).
Last updated on 08 February 2004. |
