2.3.1.  November 3, 1997

This event was not accompanied by a  proton flux increase near the Earth, but we analyze it because the event includes a halo CME and precedes two large solar proton enhancements of November 4 and 6 (see below).

     A number of impulsive and quasi-impulsive flares occurred on November 3 in an extended active complex AR 8100 (points 1 and 2 on Figures 10-12). One of them was a SB/C.8.6 flare at ~04:35 UT which was associated with a faint loop CME over the SW limb. However, we will be concentrated on a 1B/M4.2 flare event with two peaks at ~09:10 and 10:25 UT. From Figure 10a  one can see that the associated CME is a partial halo with the brightest part over the W limb but also with the noticeable SW and NW components.

Besides the south AR 8100, two north active regions AR 8099 (point 8) and 8103 (point 11), as well as several filaments and faint plages were present on the disk. The modified SOHO/EIT movie and images at 195 Å (Figure 11 ) display many large-scale chains and show that all active regions and other elements of the activity mentioned above were connected between each other. The both aforementioned flare events  appeared to be accompanied by the EUV coronal waves, but fainter than the events considered in Section 2.1.

Let us start with the morning images (a,b) that appear to be related to the 04:35 UT event. At first (a), a number of chains (mainly thin ones), extending through the whole disk, crossing each other and the helioequator, can be distinguished: 1-16-3, 16-8, 3-9-11,  3-16-7-4,  10-6,  6-7, 6-8-4, 4-5-2, 13-5. Then (b) the chains, concentrating to the main region 1 and nearby, become more pronounced: 1-2-12, 1-13, 1-9, 1-16-10, and others.

Directly before a halo CME (c), the close relations between activity in the S and N hemispheres become more obvious, particularly via the chains 1-14-6, 1-19-3, 3-11, 3-12-2. 9-15-19-12, 12-2-1, 1-13, 13-8-21.

At the multi-hour post-eruption stage (d-f), the main chains, mentioned in the previous paragraph, continue their existence and variability. In particular, the chains 11-15-19-12, 1-19-9, 17-14-13, 12-19-16-14-6 (with a probable connection to a bright branch going to point 22 near the NE limb), 12-1, and some others can be noted. Gradually, a large trans-equatorial loop-like chain 1-18-14-17 becomes visible. An involvement of the NW sector in this event manifests itself via connection of a chain branch 1-13 with  points 8, 20, 21 and restructuring of the large-scale emitting elements in this quadrant. Perhaps, it can explain the observed presence of the NW component in the associated halo CME. It seems to be important because the same feature is characteristic of two next events, especially of a CME occurred on November 6 when just its NW leg predominated over SW one (Section 2.3.3.)

The connection between all active regions and structures on the disk  and presence of the main large-scale chains, mention above, are displayed also by the Yohkoh/SXT image (Figure 10d) as well as by comparison of the 195 Å images with the EIT images at 284 and 171 Å for two time intervals during the post-eruption stage (Figure 12 ).