HELIOS no. 57        06.Aug. 1999

This Helios Newsletter continues a series newsletters under the same name as above and that were issued as the newsletter of the Solar Section of the Norwegian Astronomical Society.  Helios no. 1 was issued on 2nd May 1979 and ended almost simultaneously as I resigned as the leader of that section, i.e. in August 1989.   Now I bring it to life again, started where I left it. 
Comments?   Post them!

SOLAR CYCLE 23 UPDATE

The activity is steadily rising and the coorelation with solar cycle 20 (1964-1976) is quite remarkable.  The solar maximum is expected in June 2000.

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Extracts from Preliminary Report and Forecast, SEL, Boulder, CO. USA:

SWO PRF 1235 05 May 1999
04 May 1999
Space Weather Highlights
26 April - 02 May 1999
Solar activity ranged from very low to moderate levels. Isolated B- and C-class subflares occurred during most days. However, activity rose to moderate levels on 29 April by virtue of an M1/1B flare at 29/1954UT from Region 8524 (N22, L = 033, class/area Eao/310 on 29 April).

SWO PRF 1236 11 May 1999
11 May 1999
Space Weather Highlights
03-09 May 1999
Solar activity ranged from low to high levels. The period began with activity at moderate levels by virtue of an M4/2N flare at 03/0602UT from Region 8525 (N17, L=299, class/area Fso/290 on 02 May) with associated Type II and IV sweeps and a halo CME. Activity dropped to low levels during 04 - 06 May with isolated C-class subflares, most of which were optically uncorrelated. Activity increased to moderate levels during 07 - 08 May with isolated M-class flares including an M4/1F at 08/1440UT with Type II and IV radio sweeps from Region 8526 (N21, L=340, class/area Dao/100 on 06 May). Activity rose to high levels on 09 May as Region 8527 (N19, L=331, class/area Eao/230 on 08 May) produced an M7 X-ray flare at 09/1807UT as it crossed the west limb.


SWO PRF 1237 18 Ma y 1999
18 May 1999
Space Weather Highlights
10-16 May 1999
Solar activity ranged from very low to moderate levels. Small- to medium-sized sunspot groups
populated the disk during the period, all of which were unremarkable in terms of structure or dynamics.  B- and C-class subflares occurred during most days. Isolated, low-level M-class flares occurred on the first and last days of the period. One of these, an M2/2N from Region 8539 (N13, L=227, class/area Dso/050 on 08 May) at 10/0531UT, was associated with a Type IV radio sweep and a full-halo CME.


SWO PRF 1238 25 May 1999
25 May 1999
Space Weather Highlights
17-23 May 1999
Solar activity ranged from low to moderate levels. Activity was at moderate levels on 17 May with an optically uncorrelated M2 at 17/0455UT and a M1 at 17/2202UT. The remainder of the period was at low levels with numerous C-class flares. The most impressive of these was a long duration C2 flare at 21/1949UT which was also optically uncorrelated. LASCO/SOHO images showed a partial-halo CME event during this period which may have been associated with Region (N36, L=098, class/area Hkx/360) on 22 May.


SWO PRF 1239 01 Jun 1999
01 June 1999
Space Weather Highlights
24 - 30 May 1999
Solar activity ranged from low to moderate levels. Low activity occurred during the first two days of the period due to several small C-class subflares produced by a few small- to moderate-sized regions.
Activity increased to moderate levels on 26 May by virtue of an impulsive M1/2N flare at 26/1932UT from Region 8552 (N19, L=347, class/area Eko/360 on 27 May). Activity declined to low levels during 27 - 28 May. However, a series of sympathetic flares occurred around 27/0900UT from Regions 8551 (N32, L=021, class/area Cso/070 on 24 May) and 8554 (N26, L=355, class/area Cao/060 on 27 May) which were followed by a Tenflare and Type II and IV radio sweeps.
SOHO/LASCO images showed a large halo CME beginning around 27/1330UT, but this was judged to be a back-side event. Activity rose to moderate levels again on 29 May due to an optically uncorrelated M1 at 29/0315UT with moderate discrete frequency radio bursts, a Type II radio sweep, and a CME (non-Earth-directed). This event likely originated from beyond the southeast limb.
Activity declined to low levels on 30 May. However, long-duration C-class X-ray events were detected at 30/0338UT and 30/1155UT. Both events had associated CMEs, but neither appeared to be Earth-directed.
The provisional international monthly mean sunspot number for May was 106.3. This was the
highest monthly mean observed so far this cycle.


SWO PRF 1240 08 Jun 1999
08 June 1999
Space Weather Highlights
31 May - 06 Jun 1999
Solar activity ranged from low to moderate levels. Numerous C-class subflares occurred during the period from a variety of small- to moderate-sized active regions. Activity rose to moderate levels during 03 - 04 June due to isolated M-class flares from Region 8562 (S16, L=292, class/area Dki/420 on 03 June) and Region 8552 (N19, L=346, class/area Eko/360 on 27 May). One of these flares, an impulsive M3/2B from Region 8552 at 04/0703UT, was associated with a Type IV radio sweep, a 360 SFU Tenflare, a partial-halo CME, and a proton event.

SWO PRF 1241 15 Jun 1999
15 June 1999
Space Weather Highlights
07 - 13 Jun 1999
Solar activity ranged from low to moderate levels during the week. Low activity prevailed through 11 June with a few C-class flares each day from a variety of small- to moderate-sized regions. Some of these flares included a C1/SF at 09/0017UT with a Type II radio sweep and a C8 at 11/1157UT associated with an eruptive prominence and a loop prominence system on the northeast limb. Other events of note were optically uncorrelated Type II and Type IV radio sweeps at 11/0039UT and 11/0051UT, respectively, followed by a proton enhancement (see the discussion below). Activity rose to moderate levels on 12 June with an M1/1N flare at 12/1336UT from Region 8583 (S13, L=097, class/area Dso/150 on 12 June) associated with a weak Type II sweep. Activity returned to low


SWO PRF 1242 22 Jun 1999
22 June 1999
Space Weather Highlights
14-20 Jun 1999
Solar activity ranged from low to moderate levels during the week. Activity was low through 16 June with isolated C-class subflares and a weak, optically uncorrelated Type II radio sweep at 16/0328UT.
Activity increased to moderate levels on 17 June due to an M3 X-ray flare at 17/1730UT with an associated weak Type II radio sweep. Space-based sensors indicated that Region 8569 (N19, L = 189, class/area Eki/370 on 14 Jun) produced this flare as it was crossing the west limb. Activity dropped back to low levels during 18 - 19 June although the frequency of C-class flares increased. Space-based images showed that most of these originated from beyond the west limb including a C5 at 18/1657UT with an associated Type II radio sweep. Activity again increased to moderate levels on the last day of the period by virtue of an M2/SB flare at 20/1535UT from Region 8592 (N23, L=346, class/area Fao/200 on 20 June) with minor radio emission. Region 8592 also produced a long-duration C5/SF flare at 20/2007UT. This appeared to herald the return of old Region 8552 (N19, L=346) which produced a proton event during its previous rotation.


SWO PRF 1243 29 Jun 1999
29 June 1999
Space Weather Highlights
21-27 Jun 1999
Solar activity ranged from low to moderate levels during the week. Region 8598 (N23, L=328,
class/area Fki/650 on 25 June), the week's dominant flare producer, provided isolated M-class flares including an M1/2N parallel-ribbon flare at 23/0709UT with a Type IV radio sweep and moderate centimetric radio bursts. This region also produced an M2/2N at 26/0512UT with minor radio emission. Region 8598 was positioned within a cluster of five regions that also included Region 8592 (N22, L=352, class/area Fao/200 on 20 June) which produced an M1/1N flare at 22/1829UT with an associated 760 SFU Tenflare, and Type II and IV radio sweeps. This region also produced an M1/2N parallel-ribbon flare with an associated Type IV radio sweep and a 240 SFU Tenflare. Another event of note was a long-duration C4 X-ray flare at 24/1412UT associated with a 15-degree filament disappearance, a Hyder flare, and a partial-halo CME. The presence of numerous small- to medium-sized groups provided the highest daily sunspot numbers observed so far this cycle. The daily 10.7 cm solar radio flux also exceeded 200 SFU for the second time this cycle.
Real-time solar wind data were available from the Advanced Composition Explorer (ACE) spacecraft for most of the period. Phi data indicated a shift to a toward (negative polarity) solar sector during 23 -24 June. Otherwise, no significant changes were noted in the solar wind flow through 25 June. Two shocks were detected on 26 June. The first occurred at approximately 26/0215UT and was followed by a minor velocity increase, a brief density increase to 34 p/cc, and periods of southward IMF Bz with deflections to minus 12 nT (GSM). The second shock was detected at approximately 26/1925UT and was accompanied by a velocity increase from 340 to 430 km/sec and enhanced particle densities, but IMF Bz remained mostly northward following the shock. IMF Bz eventually turned mostly southward during the latter half of 27 June with maximum deflections to minus 13 nT (GSM). Both shocks were followed by sudden impulses at Earth.


SWO PRF 1244 06 Jul 1999
06 July 1999
Space Weather Highlights
28 Jun - 04 Jul 1999
Solar activity was at moderate levels during most of the week. There were four regions of interest during the period. Region 8598 (N23, L=328, class/area Fki/650 on 25 June) showed moderate magnetic complexity, but slowly decayed through the week. Nonetheless, it managed to produce an M1/SF flare at 30/2012UT and an M1/1F at 01/2143UT, neither of which were impressive in radio aspects. Region 8602 (N18, L=297, class/area Dko/270 on 02 July) grew slightly during the early part of the period and produced an M1/SF flare at 29/0510UT accompanied by a Type II radio sweep. Region 8603 (S15, L=286, class/area Fai/360 on 27 June) also grew gradually during the first half of the period and was one of the most productive regions of the period. It produced a few M-class flares including an M1/1N at 29/1913UT, an M1/1B at 30/1130UT associated with a halo-CME (which caused a geomagnetic disturbance on 02 - 03 July), an M2/2B parallel-ribbon flare at 30/1808UT, and an M1/1N at 01/2331UT. The final region of interest was 8611 (S25, L=258, class/area Fai/420 on 04 July). It grew gradually throughout the period, displayed moderate magnetic complexity, and was the most flare-productive of the visible regions. It produced an M3/1N parallel-ribbon flare at 29/0821UT, an M2/1N at 30/0446UT, an M2/1B at 02/0138UT, and an M1/SF at 02/1520UT associated with a partial-halo CME. Solar activity dropped to low levels during the last two days of the period as Regions 8602, 8603, and 8611 appeared to stabilize. Region 8598 rotated out of view late in the period.
Real-time solar wind data were available from the Advanced Composition Explorer (ACE) spacecraft for most of the period. Two transient signatures were detected during the period. The first occurred on 28 June as velocities increased from 550 to 890 km/sec, densities briefly increased to 18 p/cc, and IMF Bz turned southward with maximum deflections to minus 08 nT (GSM). This transient was probably associated with a partial-halo CME seen on 24 June. The second transient structure was detected early on 02 July as a shock passed the spacecraft at
02/0024UT accompanied by a velocity increase from 480 - 700 km/sec, increased particle densities, and periods of southward IMF Bz with maximum deflections to minus 08 nT (GSM). This structure was likely associated with the 30 June halo-CME from Region 8603.


SWO PRF 1245 13 Jul 1999
13 July 1999
Space Weather Highlights
05 - 11 Jul 1999
Solar activity was at low levels during the week, with the exception of a single M-class event that occurred on 05 July. Region 8611 (S26,L=256, class/area Fai/380 on 05 July) produced an M1/1F flare at 05/1848UT. Numerous C-class events were produced by several different regions, none of which appeared significantly complex.


SWO PRF 1246 20 July l999
20 July 1999
Space Weather Highlights
12-18 July 1999
Solar activity was mostly low with moderate conditions experienced on 16 July. On that date fast growing Region 8635 (N44, L=143, class/area Eao/140 on 16 Jul) produced an M3/0N event at 16/1551UT. Region 8627 (S14, L=098, class/area Eao/160 on 16 Jul) produced an M1/SF at 16/1731UT. The only other region of note was Region 8636 (N20, L=337, class/area Eao/310 on 18 Jul). This is believed to be returning Region 8598, which produced several C and M-class events during the last rotation. Currently this region is producing consistent C-class events and is showing continuous plage fluctuations and Real-time solar wind data were available from the Advanced Composition Explorer (ACE) spacecraft for most of the period.


SWO PRF 1247 27 July l999
27 July 1999
Space Weather Highlights
19-25 July 1999
Solar activity was low to high during the period. High conditions were experienced on 19 July due to an M5/2N event at 19/0846UT from Region 8636 (N20, L=334, class/areaEai/330 on 19 July). This event also produced Type II and IV sweeps. Region 8636 continued to grow in size and complexity until near the middle of the period. It then began to simplify and show signs of decay toward the end of the period. High conditions were also experienced on 24 July. This was due to 5 M-class events that day. Two were optically uncorrelated and the other three were from Region 8645 (S26, L=251, class/area Dko/190 on 24 July). Region 8645 is thought to be the returning Region 8611, which produced multiple C and M-class events during its last rotation. Moderate conditions were experienced on 23 and 25 July. Solar activity was low on 20-22 July. The only other region of note was Region 8639 (N38, L=032, class/area Dao/230 on 25 July). This region produced an M2/SF on 25/1338UT accompanied by Type II and IV sweep frequency bursts.


SWO PRF 1248 04 August l999
03 August 1999
Space Weather Highlights
26 July - 01 Aug 1999
Solar activity ranged from low to high levels. The week began with activity at low levels, then
increased to moderate levels on 27 July due to an M3/1N at 27/1405UT from Region 8636 (N21, L=332, class/area Fki/610 on 27 July). Moderate activity continued through 28 July with a couple low-level M-class flares from Region 8649 (S15, L=271, class/area Dao/170 on 30 July) including an M1/SF at 28/0201UT with a Type IV radio sweep and a 450 SFU Tenflare. Activity increased to high levels on 29 July by virtue of an impulsive M5/1N flare at 29/1934UT from Region 8651 (N24, L=204, class/area Ekc/870 on 01 August) accompanied by minor discrete radio emission. Activity returned to moderate levels on 30 July with another isolated, low-level M-class flare from Region 8649. Activity decreased to low levels during the last two days of the period with occasional C-class flares from Regions 8645 and 8651.
Real-time solar wind data were available from the Advanced Composition Explorer (ACE) spacecraft for most of the period. No significant changes were observed in the solar wind flow through 29 July. A coronal mass ejection signature was evident on 30 July with a velocity increase from 380 - 680 km/sec, increased densities, and a period of sustained southward IMF Bz with deflections to minus 12 nT (GSM).
No proton events were detected at geo-synchronous orbit during the period.
The greater than 2 MeV electron flux briefly reached high levels on 26 July. Otherwise, fluxes were at normal to moderate levels.
The geomagnetic field was at quiet to unsettled levels through 29 July. A sudden storm
commencement occurred at 30/1948UT (89 nT, as measured by the Boulder USGS magnetometer) followed by active to major storm levels with brief severe storm periods at high latitudes. The disturbance declined to unsettled to active levels on 31 July, then ended early on 01 August. The field was at quiet levels for the remainder of the period.

Space Weather Outlook
04 August - 30 August 1999
Solar activity is expected to range from low to moderate levels. Regions 8645 and 8651 are likely to produce additional isolated M-class flares. There will also be a slight chance for a major flare sometime during the period.
There will be a slight chance for a proton event at geo-synchronous altitude.
The greater than 2 MeV electrons flux at geo-synchronous altitude is expected to be at normal to
moderate levels during most of the period.
Geomagnetic field activity is expected to be at unsettled to active levels during 05 August due to recent CME activity. Active levels are also possible around 18 August due to coronal hole effects. The geomagnetic field is expected to be at quiet to unsettled levels during the remainder of the period, barring any Earth-directed coronal mass ejections.

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New members since 01.May 99:

We wish you all welcome!

Helios no. 58 will be issued 01. Nov. 1999

CV-Helios Network 07 aug 1999