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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.
Three of the six observations made during the month revealed spotless disks. On the 16th, two groups were seen in the southern hemisphere, one being of type Cao at 8ºS/201º and the other being a small pore at a high latitude of 34ºS (and at longitude 164º). Observations on the 24th and 25th showed a single pore at 16ºS/50º together with a following region of faculae. Prominent southern polar faculae were seen on the 13th and 14th.
The first observation of the month, on the 3rd, revealed two small Dsi groups, one in each hemisphere at 7ºN/11º and 20ºS/327º. Both of these groups were still present on the 5th but the southern group had decayed into a Hsx group and was last seen as an Axx spot on the 9th. During the remainder of the month, only two small groups were seen at 11ºN/196º on the 18th (type Bxo) and at 26ºN/4º on the 25th (type Axx). Spotless disks were seen on the 15th and 23rd. Prominent southern polar faculae were seen on the 5th, 8th and 15th.
After the first two observations of the month, on the 1st and 2nd, showed blank disks, the observation on the 6th revealed a Hsx spot near the eastern limb. This group, at 7ºN/209º and of type Cao, was seen on subsequent observations up to and including the 14th. This group is likely to be the same as the group last seen near the western limb on the 18th February. On the 14th and 15th a high latitude Axx group at 31ºS/210º was seen. Also on the 15th, a small Cao group had appeared since the previous day at 4ºS/199º. The next four observations, on the 21st, 22nd, 25th and 27th, showed spotless disks. An area of faculae seen on the 27th near the eastern limb heralded the appearance of a Dao group at 24ºS/297º on the following day. This group developed into an Eai type with an area of 110 millionths by the 30th. When seen on the 31st, the leading spot had decayed reducing the group area to 70 millionths.
The group at 22ºS/297º seen at the end of March changed form during the first six days of the month. The leading penumbral spot decayed on the 1st and 2nd before reappearing on the 3rd. On this date, the longitudinal extent of the group was 12º. On the 4th the leading spot decayed again. The rest of the group then decayed to leave only a small Hsx spot when seen on the 6th. Due to the decay of the remainder of the group, this spot had a revised location at 22ºS/289º i.e. some 10º from the mean group location on the 1st. By the 7th the Hsx spot had disappeared leaving only an extensive area of faculae visible. On the 3rd, a small Cao group appeared near the eastern limb (mean location 28ºS/212º). On the following day only a single Hsx spot was seen - between the 5th and 8th this spot was accompanied by several pores. By the 9th, the penumbral spot decays such that on the 10th and 11th, the group became type Axx. No spots were seen on the 12th but an area of faculae was seen towards the western limb on the 13th. On the 9th, a compact Cao group was seen for the first time at 25ºN/217º. On the following day this group had increased in size to be of Dsi type. On the 10th and 11th a light bridge could be seen between the two main umbra within the leading spot. The group subsequently decayed as it approached the western limb. On the 10th only an Axx group was seen at 10ºN/215º. An area of faculae in the location of this group was seen on the 12th and 13th as it neared the solar limb. On the 12th another high latitude group at 29ºS/192º appeared which was only 10º following the Axx group seen the day before. This group had developed two rudimentary leading and following penumbral spots by the 13th and continued to develop into a type Dso group before passing ground the western limb on the 16th. Another D type group appeared on the 14th at 22ºS/112º which initially consisted of just two small penumbral spots but then developed into a group with a number of small spots and pores (when seen on the 15th and 16th). Following four blank disk observations on the 19th to 22nd, a single Axx spot was seen on the 23rd and 24th at 18ºN/324º. The observation on the 28th revealed a small Cro group at 16ºS/9º - only an area of faculae on the western limb was seen on the 30th (when no spots were seen). Southern polar faculae were seen on the 16th. Although no large area spots were seen, the monthly AA and R values are both significantly higher than over recent month. From personal observations, AA is the highest since December 1995 and R is the highest since March 1995. It is encouraging to note that the majority of the 8 groups seen during the month have been at high latitudes and are thus part of the new cycle.
The first four days of the month revealed a spotless disk. Then on the 5th a Hsx spot appeared around the eastern limb. This spot was seen for all the remaining observations made during the first half of the month and its appearance changed very little during this period. The mean location of the spot was 20ºN/140º and for all observations, except on the 13th, consisted of a single penumbral spot which obtained a maximum area of 70 millionths. On the 6th, a small Bxo group was seen at 23ºN/197º which was not seen on the 7th and 9th but reappeared on the 10th and 11th to disappear again by the 12th. Observations resumed on the 25th to reveal three small groups. One of these was a small Hsx spot seen at the low latitude of 7ºN/23º and near the western limb (this group was seen again on the 26th but not the 27th). The other two groups were at 34ºS/306º and 25ºS/269º - both of type Bxo. The first of these was not visible on the 26th but the other persisted until the 27th. By the 26th two additional groups had appeared, one at 2ºN/9º (type Axx) and the other at 29ºN/3º (type Cro) but both had disappeared by the following day (leaving areas of faculae visible near the western limb). On the 27th another small group was seen near the eastern limb at 26ºN/212º which developed into a Cro type when seen on the 29th and 30th. A single Axx spot was seen at the edge of a region of faculae near the eastern limb on the 30th (at 28ºS/189º). This region of faculae had been seen on the previous day on the limb.
When the first observation of the month was made on the 8th, the group seen at the end of May was still visible. The group was of type Cro on the 9th and Hsx on the 9th when it was seen near the western limb (mean location 26ºS/190º). Also on the 8th two Axx groups, each consisting of a single spot, were seen at 22ºN/132º and 28ºN/67º. The first of these groups had disappeared by the following day while the second was seen up to and including the 16th during which time it had only developed into a small Bxo group. Between the 12th and 18th another small group was seen at 19ºN/29º. This was initially of type Bxo before developing into type Cro. When seen on the 16th a small penumbral spot was seen together with 13 other spots. On the 18th and 20th a small Bxo group was seen at 27ºS/322º before there was a blank disk on the 21st. On the 22nd yet another small Bxo spot was seen at 16ºN/291º while only an Axx group at 18ºN/284º was seen on the last observation of the month on the 28th. The average R for the month is similar to the last two months (20.6). All the spots seen were small in area (less than 30 millionths).
The first spots of the month were seen on the 7th after five blank disk observations. On this date three southern hemisphere groups were seen but all were small and short-lived. These were of type Bxo at 29°S/136° which was last seen on the 9th as it neared the western limb surrounded by an area of faculae, of type Bxo at 28°S/126° and seen only on the 7th, and of type Axx at 15°S/109° and last seen on the 8th. On the 9th another Bxo group was seen at the center of the disk (at 4°N/82°) but appeared for only one day. There were a further seven blank disks before an extensive area of faculae was seen near the eastern limb on the 18th which contained a single pore at 25°N/266°. No other spots were seen from this region until the 22nd when a single spot at 27°N/259° was seen. This developed into a Cro group on the 23rd before decaying on the disk (last seen on the 26th). Between the blank disk observations of the 19th and 21st, another short lived Bxo group was seen at 24°S/299°. On the 23rd a Bxo group appeared around the eastern limb (at 24°N/188°) which had decayed into a single spot by the 27th before growing into a collection of 8 small spots stretching 8° in longitude on the 28th. It had subsequently decayed by the 29th and was not visible on the 30th. On the 24th, a group of 7 spots, some with rudimentary penumbra, appeared on the disk at 16°N/278°. By the following day this had developed into a Dao bipolar group with two main penumbral spots and a total area of 80 millionths - the largest area group of the month. This group was last seen on the 27th before passing around the limb. An Axx group was seen on the 26th and 27th only at 26°N/152°. The last observation of the month, on the 30th, showed a blank disk. All but one of the groups seen this month were at high latitude but with the exception of the D type group, all were very small in size. The monthly R and AA means were lower than recent months due to the presence of 15 blank disk observations, although a total of 4 groups were seen on the 26th when R had a value of 52.
Very little activity was seen at the start of the month. On the 2nd a single Axx spot was seen at 7°N/53° enclosed in an area of faculae near the eastern limb. By the 3rd a small Cro group had developed on the disk at 19°S/72° which, by the 6th, had changed into a single Hsx spot before it had decayed on the disk by the 9th. On the 5th another two groups had formed on the disk. The first of these started as a Bxo group (at 21°N/112°) before developing into a Dso group by the following day with an area of 90 millionths. It disappeared around the western limb on the 9th. The other group started as an Axx spot surrounded by an area of faculae near the eastern limb. It then changed into a small Dso group at 18°S/26°. On the 8th it had a longitudinal extent of some 8°. The group then proceeded towards the western limb, reducing in size slightly and was last seen on the 15th. On the 8th another single Axx spot was seen near the eastern limb at 26°N/337°. This turned into a Cro group and then into a small Hsx spot before decaying on the disk by the 16th. On the 11th two penumbral spots appeared close the eastern limb at almost the same longitude. The northern most of these, at 27°N/279°, decayed slowly and was last seen near the central meridian as a single spot on the 17th. The southern penumbral spot, at 16°N/282°, proceeded across the disk as a Hsx spot and was last seen on the 21st. Its maximum area was 70 millionths when seen on the 15th. The next three groups were all only visible for one day each and all were of type Axx (at 28°N/260° on the 15th, 22°N/303° on the 16th and 27°N/269° on the 19th). Observations on the 23rd and 24th showed no spots but on the 24th an extensive area of bright faculae enclosed in an area 10° by 10° had appeared near the eastern limb. The location of the faculae was that of the Dso group which had passed around the limb on the 9th. By the following day a Cao group was seen in a northern extension of the faculae. This group, at 29°N/109°, rapidly grew into an Esi type. On the 29th it comprised a leading penumbral spot containing several umbra followed by 24 small penumbral and other spots and had a total area of 230 millionths. On the 31st the leading penumbral spot had reduced in size slightly but the longitudinal extent of the group had become 15°. Four other small groups were seen during the period from the 25th. An Axx group was seen on the 25th and 26th only at 24°S/113° while another small group was seen at 17°N/120° on the 27th to 29th. On the 31st two small Hsx spots were seen at 18°N/134° and at a high latitude of 37°N/16°. Activity this month has increased significantly, especially with the northern hemisphere Esi group seen towards the end of the month. The monthly average R value was almost three times that of July 1997 and the highest seen since March 1995. The number of active areas peaked at 5 on the 15th and only two blank disks were seen during the month. Most of the activity was in the northern hemisphere and except for the first group of the month, all the groups had latitudes greater than 15°.
The first observation of the month, on the 2nd, showed three northern hemisphere groups - a Fsi group at 25°N/109°, a Hsx spot at 35°N/18° and an Axx spot at 22°N/10°. The Fsi and Hsx groups were those seen at the end of August. The Fsi group consisted of a modest leading penumbral spot, four smaller following penumbral spots and a collection of 24 following spots. This group subsequently decayed into a Hsx group on the 4th and was last seen as an Axx spot close to the western limb on the 6th. The Axx and Hsx groups seen on the 2nd had decayed on the disk by the time of the next observation on the 4th. On the 4th an Eao group had appeared on the disk at 27°S/358° and with an area of 200 millionths. Subsequent observations showed this group developing into type Dki by the 10th with an area of 520 millionths. On this date, the group consisted of almost equal sized leading and following penumbral spots together with two small penumbral spots and 13 other spots in between (see attached sketch). This group had changed into type Eko when last seen on the 13th near the western limb. Three new groups were seen on the 6th and all were in the northern hemisphere. The first of these was of type Axx (at 34°N/9°) which had decayed by the following day. The second was a small Dso group at 21°N/5° which had an area of only 60 millionths before decaying on the disk on the 9th. The third group was initially seen as type Hrx with an accompanying area of faculae close to the eastern limb. This group slowly developed into type Dsi with an area of 90 millionths when near the central meridian on the 10th (see attached sketch) before the leading spot doubled in area by the 11th and the group becoming type Esi. This group's mean location was 22°N/322°. The second F type group of the month appeared around the eastern limb on the 7th surrounded by an area of faculae. The leading penumbral spot of this group contributed to most of its area which was at a maximum on the 10th at 570 millionths. On the 13th, this group comprised of the leading penumbral spot and a string of following spots covering 17° of longitude (mean location at 24°S/297°). When seen on the 16th, all the following spots had decayed (just leaving an area of faculae visible). The remaining penumbral spot was last seen on the 18th close to the western limb. On the 12th an Axx group was seen near the eastern limb at 27°N/229°. This developed into a small Dsi group by the 16th and an Eso group by the 18th before most of the following spots decayed to leave a Hax spot by the 22nd. From the 21st to 23rd a Hsx spot at 21°S/106° was seen near the eastern limb. On the 22nd a Dso group had developed on the disk at 28°S/127° which was still present as an Eso group with an area of 260 millionths by the last observation of the month on the 26th. Finally, on the 23rd a single Axx spot was seen at 21°N/111° - this was just to the south of a large area of faculae where the Fsi group seen at the start of the month was located. Activity this month has increased once again. In fact R has been almost twice that of August. This has been due to the presence of the six groups with areas of greater than 150 millionths, two of which had areas just greater than 500 millionths.
On the 4th two small groups were seen at 25°S/348° (type Hrx) and at 24°N/331° (type Dro). By the 6th the northern group had decayed into type Axx and both groups had decayed on the disk by the 9th. On this date another two small groups had appeared in the eastern hemisphere at 25°N/273° (type Axx) and at 32°N/255° (type Cro). The first of these was seen on the 10th but not on the 12th while the second group developed into type Dso when seen on the 10th and 12th and then type Eso on the 18th when it was located near to the western limb. Also on the 10th a Bxo group was seen just to the west of the central meridian (at 23°N/308°). By the 12th this group comprised of 8 small spots and all were without penumbra. On the 12th only a small Bxo group was seen at 30°N/216°. On the 18th Hsx (at 13°N/170°) and Cso (at 17°N/140°) type groups were seen to the east of the central meridian. The Hsx group decayed into a Bxo group by the 21st and was not seen on the following day. The Cro group lost its following spot by the 19th to become type Hax and then into type Hsx as its size decreased. It was last seen near the central meridian on the 22nd. The observations on the 23rd showed a spotless disk - the first since 24th August. On the 25th a small Cso group at 20°N/24° was seen close to the eastern limb surrounded by a bright compact region of faculae. By the 28th this group had developed into a Dso group before becoming type Cso on the 29th and 31st. Also on the 28th a Dao type group was seen near the eastern limb at 19°S/352°. When seen on the 29th the largest penumbral spot was quite asymmetric in shape and the whole group had a corrected area of 180 millionths. By the 31st the corrected area increased to 290 millionths to become the largest group of the month. The largest spot comprised several umbra and a light bridge within the penumbra. On the 31st a small Axx group was seen within an area of faculae near the western limb (at 18°S/77°). Activity this month has reduced compared to August and especially to September. This reduction is not only the result of a reduced number of groups and spots but also in the size of the groups. This month has seen many more northern hemisphere groups (8 northern and 3 southern hemisphere).
The observation on the 1st showed the Eai group seen at the end of October (at 18°S/354°). Subsequent observations on the 2nd and 4th showed the group developing into types Eki and Fkc respectively. The area of the group rapidly increased from 270 millionths on the 1st to 720 millionths on the 4th with the following penumbral spot being the largest spot of the group. The axis of this group had a high inclination such that the preceding spot was 7° nearer to the equator than following spot. By the 8th the group was close to the western limb and only the large following penumbral spot could be seen. The attached sketch shows the development of this group from the 28th October to 8th November (the cross is 0° latitude on the central meridian for a Bo of +4°). Also on the 1st, the Cso group seen at the end of October had decayed into type Hrx (at 19°N/30°). On the 2nd and 4th this group was of type Axx. On the 2nd a short-lived Cso group was seen at 29°N/327° and was last seen on the 4th as type Axx. A collection of small spots was seen at 24°N/305° on the 4th - these subsequently developed into type Cso on the 8th and Dao on the 11th when the group was near the western limb. Also on the 8th a Hsx spot was seen at 28°N/208° together with a high latitude Bxo spots at 34°S/244°. These two groups were not seen on the 11th. A small Cso group was seen on the 11th at 29°N/266°. The next observation on the 22nd showed the second Eai group of the month at 20°N/116°. This group comprised three similarly sized penumbral spots at preceding, center and following locations together with a few smaller spots. The area of this group was estimated at 370 millionths on the 22nd and 300 millionths on the 23rd. Unlike the E type group seen at the start of the month, no axis inclination was evident (in fact the group lied almost exactly along the 20°N latitude line). A Hsx spot at 17°S/95° and an Axx spot at 23°N/4° were seen on the 22nd and both developed into Cso groups by the following day. A single Axx spot was seen near the eastern limb on the 23rd at 16°S/5°. Only the northern Cso group was seen on the 27th (the Eai group would have already passed around the limb) but it had decayed into type Axx. This single spot was still present on the 28th and 29th. On the 27th the third E type group of the month (this time type Eko) was seen near the eastern limb (at 21°N/312°). This was the reappearance of the Dao group last seen on the 11th. By the 29th the asymmetric leading penumbral spot had split into two giving a symmetrical penumbral spot to the north and an irregular penumbral region to the south. The following part of the group consisted of three small penumbral spots and a few other spots (hence the group classification of Eho). The area of the group was estimated at 590 millionths on the 29th. R is slightly less than September and activity this month has been dominated by the three E type groups, one of which became type F and had the largest area seen so far this solar cycle.
The E type group seen at the end of November had decayed into type Cso by the first observation of the month on the 6th. This group at 21°N/309° and now near the western limb comprised one leading penumbral spot containing several umbra together with two following small spots. The area of the group had decayed from 590 millionths on the 29th November to 330 millionths on the 6th. The group was seen on the 7th but not on the 10th as it would have disappeared around the limb. The second group seen on the 6th was a high latitude Axx spot at 34°N/287° - this changed into type Bxo by the 7th but it was not seen again. The third group of the 6th was a small Cso group at 25°N/227° and it had a small symmetrical penumbral spot and a few following spots. This group had a similar appearance on the 7th but by the 10th another penumbral spot with following spots had appeared 6° to the north thus changing the average position of the group to 29°N/226°. This collection of spots (classified as type Dso) persisted until the 13th by which time the southern penumbral spot had decayed into a single spot. The group was last seen on the 14th when near the western limb. On the 7th only a Bxo group was seen at 21°N/202°. A small Hrx spot was seen at 26°N/258° between the 10th and 12th before passing around the limb. On the 10th another Cso spot was seen on the 10th at 22°S/190°. Nothing at this location was seen on the 11th (probably due to poorer seeing conditions) but a single Axx spot was seen on the 12th before disappearing on the 13th. A single Hsx spot was seen at the high latitude of 39°S/189° between the 10th and 14th. It had an area of only 40 millionths. On the 11th a Dso group appeared near the central meridian (at 30°N/193°). By the 13th it had developed into a small Eso group with an area of 150 millionths. It was also seen on the 14th. On this date a Bxo group was seen near the eastern limb at 17°N/85°. After a gap of 12 days, the next observation on the 26th showed a southern Esi group (at 20°S/349°) and a northern Hax spot at 22°N/308°. Both had areas of 190 millionths. The Esi group was still present on the 31st as it neared the western limb and it comprised a string of three roughly equal size penumbral spots together with several intervening spots. The Hax spot had a large region of following faculae when seen near the western limb on the 26th and 27th. This spot contained several umbra and on the 31st a light bridge appeared within the penumbra. This was the group's second reappearance onto the disk (it was first seen on the 4th November). An Axx spot was seen at 27°N/30° on the 27th only while another Axx spot was seen on the 29th at 28°S/280°. This latter spot developed into a Dso group by the 31st. The monthly averaged R is similar to November and slightly less than September while the active area MDF is the largest seen so far this solar cycle.
Last updated on 25 April 2002. |
