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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.
The most notable group seen during the month was first seen on the 20th. This was a Dao type group at -19°/321° (AR 848) which had an area of 120 millionths. By the next day more spots had appeared between the symmetric leader and the slightly larger asymmetric follower. Some of these had penumbra. The group now straddled the central meridian, it was of type Dac and it had an area of 200 millionths. The next observation on the 24th showed the group to be of a similar total area but it now comprised a string of small penumbral spots at the leader part of the group and another string at the follower part. The group had a similar appearance on the 25th but by the 27th only two small penumbral spots were seen near the western limb. There was only one observation with sunspots in both hemispheres, this being on the 15th. The solar disk was spotless on the 28th with only the north being spotless on the 20th, 21st, 24th, 25th to 27th and 29th while only the south was spotless on the 5th, 6th and 11th.
Only four small groups were seen during the month. The first three groups were of type Axx at 10°S/87° on the 8th (AR 852), type Cso at 8°S/120° on the 9th (AR 853) and type Axx at 5°N/308° between the 14th and 16th (AR 855). The fourth group, at 6°S/329°, was of type Dso with an area of 60 millionths on the 15th and type Axx when seen on the 16th (AR 854). Spotless disks were seen on the 5th, 10th, 21st, 25th and 26th while the northern hemisphere was spotless on the 8th and 9th and the southern hemisphere was spotless on the 14th.
The largest of the 7 groups seen from the 13 observing days between the 1st and 25th was initially seen as an Axx sunspot on the 15th (AR 860). By the 18th it had developed into a Cso group at 6°S/302° with an area of 30 millionths. On the following day some of the other spots had formed penumbrae to make the group type Dsc: the total area was still small at 110 millionths. When next seen on the 23rd it had decayed to type Bxo. Spotless disks were seen on the 1st to 3rd, 6th, 11th and 25th and in addition the northern hemisphere was spotless on the 4th, 5th, 15th, 18th and 19th and the southern hemisphere was spotless on the 13th. This meant that sunspots were seen in both hemispheres on only two occasions, the 5th and 23rd.
Activity during the month was much higher than recent months but only in the southern hemisphere; of the 13 groups seen from the 16 observing days only 1 was in the northern hemisphere. On the 2nd there was an Ekc group on the central meridian at 11°S/111° (AR 865) with an area of 230 millionths. The main spot of the group was the leader penumbral spot; a smaller irregular penumbral spot was seen following. By the 4th, the main spot had increased in size as had the follower to give a total area of 590 millionths. This group was seen with the protected naked eye. The appearance of the leader spot had changed again by the 5th into a much more irregularly shaped sunspot with several umbrae within it. By the 6th the group began to decay such that it was of type Hkx with an area of 360 millionths as the following penumbral spots had disappeared to be replaced by a few small spots. When last seen on the 8th just the penumbral spot was seen close to the western limb. To the east of AR 865 were 3 much smaller groups, AR 866, 867 and 868. After these had rotated off the disk, the other 5 groups seen up to the 22nd were all small in size. The sun was spotless on the 22nd. The largest of the three groups on the 26th was the return of AR 865, as AR 875 at 10°S/115°. It was much smaller at 260 millionths and of type Dac with the main spot being irregular in shape. On the 29th it just consisted of an irregular spot with an area of 110 millionths. It was of similar appearance on the 30th but with more surrounding spots. Hydrogen Alpha: A quite striking prominence was seen on the western limb on the 7th and 8th which had the form of a spire but with no hydrogen being present in its middle portion. On the 8th the spire shape had filled in except for near its base. On the 22nd a collection of tree shaped prominences were seen on the western limb covering some 25° along the limb.
Although none of the 19 observing days were spotless, all of the 14 groups seen during the month were small. The largest group was AR 882 which appeared on the disk between the 5th and 7th as a Dso group at 13°S/34° with an area of 60 millionths. By the 9th its area was estimated to be 190 millionths through the development of the leading penumbral spot. The group then decayed such that it was of type Cso on the 10th and 11th when it was close to the western limb. The next largest group was AR 875 at 9°S/113° which had an area of 100 millionths on the 2nd when it was of type Hax (this group was the return of AR 865 from early April). The size of this group reduced as it neared the western limb; it was last seen on the 5th. On the 28th and 29th a group was seen very close to the solar equator at 0°/91° (AR 889). On the 28th it was of type Cao and on the 29th it was of type Hsx with an area of 30 millionths on both dates. The northern hemisphere was seen spotless on the 7th, 9th to 13th, 20th and 21st (spots were seen in the southern hemisphere on all observing days). Hydrogen Alpha: The most striking prominence seen during the month was first seen on the 9th as a 'flame' on the NE limb at about 35° N. On the 10th it had a similar appearance but by the next day its appearance had completely changed. It looked like a 'tree' with many ' branches' and it height was more than twice that of the previous day. There was no trace of this prominence on the following day (12th). Clearly a dramatic change had occurred between the 10th and 11th.
During the month only five groups were seen. The first of these, AR 892, was seen on the 5th as an Eao group at 6°S/284° with an area of 170 millionths. As it progressed towards the central meridian it developed a few small following penumbral spots and obtained its maximum area on the 7th. By the 10th it had lost all its following penumbral spots to make the group type Cai as there were still several other following spots. However these had disappeared by the 11th to leave an Hax spot. This spot was last seen close to the western limb on the 15th. The next group, AR 893, was seen close to the solar equator at 0°/262° . This group was initially seen as a Dao group on the 7th which became type Dso with an area of 120 millionths on the 8th. By the 10th the following penumbral spot had decayed to become type Cai on the 10th and then type Hax on the 12th. This spot must have decayed on the disk as it was not seen on the 14th. The third group, AR 896, developed on the disk as a Bxo group at 10°S/151° on the 16th. By the 18th a small Hsx spot had formed which was subsequently seen again as a Bxo group on the 20th and 21st. This group had disappeared by the 22nd. On the 27th a Csi group was seen near the eastern limb at 7°N/6° (AR 897). By the following day more small penumbral spots had developed to make the group type Dac with an area of 110 millionths. As the group progressed towards the central meridian the number of spots within the group reduced. On the 28th the final group of the month was first seen close to the eastern limb (AR 898) at 6°S/328°. On the 29th and 30th a small nearby penumbral spot had appeared; on the 30th the total area of this group was 300 millionths. Spotless disks were seen on the 3rd and from 22nd to 24th while just the northern hemisphere was seen spotless between the 14th and 18th, and on the 20th and 21st. Hydrogen Alpha: The most striking prominence during 19 observing days was seen between the 5th and 8th on the NW limb at about 50° N. This prominence was initially seen as a flame prominence which then proceeded to split into two parts over the next 3 days. Nothing was seen of this prominence on the following day, the 9th. A dark filament was initially seen on the 21st close to the SE limb. When seen on the 23rd and 24th the filament was particularly dark and a little broader than on the 21st; its length was estimated to be about 20°.
One of the two groups from the 1st was visible with the protected naked eye. This was AR 898 which comprised a slightly asymmetric penumbral spot at 5°S/330° and hence was of type Hkx and it had an area of 310 millionths. As this spot neared the central meridian it was of a similar size although it became more elongated in the north/south direction - the umbra started to split into two. This group was close to the central meridian on the 4th. By the following day the penumbral spot had elongated further and it had several umbrae. This was the last day it was visible with the protected naked eye. By the 7th the penumbra had split into two making the group type Dko. The group decayed further as it progressed towards the western limb and it was last seen on the 9th. The other group seen on the 1st was AR 897 of type Cso at 8°N/6° was last seen on the disk on the 4th of type Axx. On the 5th AR 899 was seen close to the eastern limb and of type Cso at 4°S/235°. It attained its maximum area on the 7th of 90 millionths and type Dso before also decaying on the disk (it was last seen as a single Axx on the 12th). There was a blank disk on the 13th before a Bxo group, AR 900, appeared on the disk at 4°S/140° on the 14th. This group remained type Bxo until it had just passed the central meridian on the 18th when it became a small Dso group with an area of just 60 millionths. It had disappeared by the 20th. There were blank disks on the 20th and 21st. On the 22nd an Hax spot was seen near the western group at 6°N/10° (AR 901). By the following day a small follower spot had appeared and further spots appeared by the 24th to make the group type Dao with an area of 90 millionths. On the next two days this group decayed slightly such that it was of type Cso on the 26th and Cao on the 28th.
After AR 902 had rotated off the disk on the 2nd, there were blank disks on the 3rd, 4th, 5th and 7th. On the 8th AR 903, type Bxo, was seen close to the eastern limb; it was also seen on the 9th but it had disappeared by the 10th. On the 9th an Hsx spot had rotated onto the disk which was accompanied on the 10th by a following penumbral spot. When seen next on the 13th this group, AR 904, comprised two moderately sized irregular penumbral spots. The following spot had changed shape the most by the following day. When next seen on the 18th, the following spot had decayed to leave an almost symmetrical leader penumbral spot and a string of small follower spots. By the 20th just the leader Hhx spot was seen at 14°S/127° and near the western limb. It was seen very close to the limb on the 21st. The only other group seen during the month, AR 905, was close to the eastern limb on the 21st as a Dso group at 6° S/328° . By the 25th, the leader spot became elongated with 2 umbrae - it was now of type Eao with an area of 230 millionths. The leader became more asymmetric by the 26th and it had split into several spots by the next day (the group straddled the central meridian). During this period and up to the 29th, the follower spot became separated from the rest of the group. On the next day the follower spot had disappeared to leave a small Cai group with an area of 80 millionths. In addition to the four blank disks during the early part of the month, no spots were seen in the northern hemisphere during the entire month. Hydrogen Alpha: While observing AR 905 in Ha on the 29th between 17h 30m and 17h 45m UT, a flare was seen just to the north of the main sunspot. After about 5 minutes, the bright area faded but another flare slightly to the north appeared. Clouds and the low altitude of the sun prevented further observation.
On the 1st the two groups seen were both close to the western limb; an Hsx spot at 6°S/335° (AR 905) and a Dso group at 7°S/320° (AR 906). Both of these groups had disappeared by the 3rd when there was a blank disk (as there was on the 4th). On the 5th AR 907 at 13°S/161° had developed on the disk as a small Cso type group while an Hsx spot, AR 908 at 13°S/133° , had rotated around the limb. AR 907 became a Hsx spot on the 6th with an area of just 40 millionths before decaying into a Bxo group on the 7th and an Axx spot on the 8th. Meanwhile AR 908 had developed into an Hax spot on the 7th and 8th attaining an area of 240 millionths by the 8th. Also on the 6th an Axx group, AR 909, developed to the north and west of AR 907 at 8°S/168°. By the following day it had changed into a small Dso group with an area of 60 millionths before decaying to a Cai group on the 8th. On the 20th, 21st and 24th just one group was seen, AR 910 at 8°S/342° , which was of type Hsx (area 30 millionths) and then type Axx on the 24th. After another blank disk on the 26th, three groups were seen on the 29th and 30th: these were AR915 at 4°S/291°, AR913 at 19°S/194° and AR 914 at 10°S/183° . AR 915 was of type Bxo on the 29th before becoming type Dso with an area of 90 millionths on the 30th. The other two groups were small Hsx spots on both dates. In addition to the three blank disks during the month, no spots were seen in the northern hemisphere during the entire month (as was the case for August).
Only four small sunspot groups were seen during the month from 11 observations. On the 2nd a Hsx spot was seen at 18°S/192° (AR 913) which was still of this type when last seen nearing the western limb on the 8th. Slightly towards the NE of this group was another Hsx spot at 9°S/185° (AR 914) - it had decayed to an Axx spot on the 7th and it was not seen on the 8th. Observations between the 12th and 16th inclusive all showed a blank disk. On the 20th and 21st a small Cso group was seen at 3°S/349° (AR 917). On the 27th an Axx spot was seen at 15°S/238° (AR 919). Hydrogen Alpha: On the 7th and 8th a pyramid type prominence was see on the SE limb an arch prominence was see in the SW limb on the 14th and 15th. The latter prominence had just one 'leg' of the prominence touching the limb when seen on the 15th. Also on the 14th a bright short prominence was seen on the western limb: over a period of 15 minutes a detached 'blob' of hydrogen could be seen drifting away from the limb.
Activity increased from October not only in the number of groups seen but also in the size of one of these which was easily seen with the protected naked eye. At the start of the month three groups were seen. An Axx spot at 10°S/228° seen on the 1st and 2nd only (assumed to be AR 919 from the end of October). AR 921 was initially seen on the 1st as an Eac group at 5°S/141° with an area of 220 millionths. This group developed larger following penumbra by the 2nd with a total area of 310 millionths. As this group passed the central meridian on the 3rd it consisted of a string of penumbral and other spots with the largest spot being at the leading position within the group. Although by the 6th the number of spots within the group reduced, the following penumbral spot become the largest sunspot within the group through the merging of several other smaller penumbral spots. This group was last seen near the western limb on the 9th as an Eso type group. The third group from the 1st, AR 922, was initially seen as a small Cso group at 13°S/126° . Although it developed into a Dac group by the 3rd it was still fairly small at 100 millionths and it subsequently decayed to an Hsx spot by the 6th. On the 9th a moderately sized Hkx spot was seen near to the eastern limb. On the 11th this penumbral spot, AR 923, at 4°S/6° had an estimated area of 850 millionths. Its shape changed slightly over subsequent days it was the following part of the spot that changed the most. By the time the group was near the central meridian on the 13th its area had reduced slightly to 720 millionths. When next seen on the 18th the penumbral spot was more symmetrical and smaller at 490 millionths. It was near the western limb on the 19th. It was also seen with the protected naked eye on the 11th, 12th and 13th. On the 13th, 18th and 19th two small groups were seen at 8°S/320° (AR 924) and 6°S/305° (AR 925) before there was a blank disk on the 23rd. On the 25th a small Hsx spot was seen at 8°S/140° (AR 926) which developed into a Cao group by the 29th with an area of 130 millionths. Also on the 29th a first northern hemisphere group was seen (the first since the end of July) - this was AR 927 at 11°N/129° which was of type Dao with an area of 90 millionths. Hydrogen Alpha: On the 5th at 12h 20m UT a flare was already in progress within the following part of AR 921. It was initially seen as four bright areas which then became elongated but not quite as bright. The flare had almost faded by 12h 50m and had disappeared when observing again at 13h 15m. The most striking set of prominences from 11 observations during the month was on the 6th when several were seen over 30° along the SW limb.
At the start of the month two groups were seen: AR 926 and AR 927. On the 3rd AR 926, at 8°S/138° was of type Dsc with an area of 160 millionths when it comprised several small penumbral and other spots. By the 4th the number of spots had reduced slightly and by the 6th the group, now near the western limb, had reduced to type Bxo. Also on the 3rd AR 927, at 9°N/130°, was of type Cso; by the 4th only a single penumbral Hsx spot was seen which had a area of 70 millionths. When next seen on the 6th and 7th it was still of type Hsx. On the 6th a medium sized irregular penumbral spot was seen close to the eastern limb at 5°S/9°. This was AR 930 and the return of the large sunspot from November (AR 923). On this date and on the 7th small penumbral spots were also present making the group type Dko. By the 9th the main penumbral spot has become more symmetric and the number of accompanying spots had reduced; its area was estimated at 440 millionths. This group was of similar appearance on the 10th but by the 12th a second umbra had appeared within a slightly larger spot (580 millionths). When next seen on the 16th this group was still of type Hkx but it appeared to be smaller and it was close to the western limb. It was last seen on the limb on the 17th. The solar disk was spotless on the 20th, the last observation of the month. Hydrogen Alpha: On the 6th at 13h00m a small flare was seen just to the south of the main umbra within AR 930. Two flares were in progress at the start of observations on the 9th at 11h 00m. These were to the west of the umbra within AR 930 and they had faded within 10 minutes. Another flare then appeared at the south end of a curved filament to the west of the main umbra - this is disappeared by 11h 15m. The most striking prominence of the month from 5 observations was on the 17th when a domed shaped prominence was seen on the SW limb at approximately 50°S.
Last updated on 22 January 2007. |
