THE SOLAR MINIMUM ACTIVE-REGION-7978, ITS X2.6 1B FLARE, CME, AND INTERPLANETARY SHOCK PROPAGATION OF 9 JULY 1996/

The first X-class flare in four years occurred on 9 July 1996. This X2 .6/LB flare reached its maximum at 09:11 UT and was located in active region 7978 (S10 degrees W30 degrees) which was an old-cycle sunspot p olarity group. We report the SOHO LASCO/EIT/MDI and SOONSPOT observati ons before and after this event together with Yohkoh SXT images of the flare, radio observations of the type II shock, and GOES disk-integra ted soft X-ray flux during an extended period that included energy bui ld-up in this active region. The LASCO coronagraphs measured a signifi cant coronal mass ejection (CME) on the solar west limb beginning on 8 July at about 09:53 UT. The GOES 8 soft X-ray Aux (0.1-0.8 nm) had st arted to increase on the previous day from below the A-level backgroun d (10(-8) W m(-2)). At the start time of the CME, it was at the mid-B level and continued to climb. This CME is similar to many events which have been seen by LASCO and which are being interpreted as disruption of existing streamers by emerging flux ropes. LASCO and EIT were not collecting data at the time of the X-flare due to a temporary software outage. A larger CME was in progress when the first LASCO images were taken after the flare, Since the first image of the 'big' CME was obt ained after the flare's start time, we cannot clearly demonstrate the physical connection of the CME to the flare. However, the LASCO CME da ta are consistent with an association of the flare and the CME. No eru ptive filaments were observed during this event. We used the flare evi dence noted above to employ in real time 3 simplified Shock-Time-of-Ar rival (STOA) algorithm to estimate the arrival of a weak shock at the WIND spacecraft. We compare this prediction with the plasma and IMF da ta from WIND and plasma data from the SOHO/CELIAS instrument and sugge st that the flare - and possibly the interplanetary consequences of th e 'big' CME - was the progenitor of the mild, high-latitude, geomagnet ic storm (daily sum of K p = 16+, Ap = 8) on 12 July 1996. We speculat e that the shock was attenuated enroute to Earth as a result of intera ction with the heliospheric current/plasma sheer.