May 22 2002 (SSC17, -109) MC, CMEH25


A very complex event !

A) WIND/WAVES: 18-22 May period of intense  activity  as indicated in the  type II and IV radio burst list:

-Type IV burst (see figure), well detected on 22 May, between #06 UT and 23 May14 UT (9000-400 kHz).

-Type II 22May 04:10 UT to 23 May: 10:40 UT (500-30 kHz). 

This event is associated with  a CME (22 May 03:50UT: CMEH25, V 1557 1504 1540 km/s).

B) Ground based instruments: During the period, one note a series of events:

*-21 May #21:23-21:35 UT:  Microwave burst (HIRAISO) detected over a broad frequency range (2.8 GHz-<50 MHz) and also a type II burst observed below 200 MHz. This event is associated with a partial halo CME ( 21:50 UT  56, PA135 V 853 804 838 km/s). (see  comment from Gareth Lawrence)

*-21 May #23:50-22 May:#04:00 UT: Another microwave burst still weaker is observed by HIRAISO) in the same frequency range. This event is associated with a CME (22May 00:06 UT: CMEP24 PA 230, PA 186, V 1246 1341 1292 km/s),  (see  comment from Gareth Lawrence)

-20 May :  Microwave burst:10:16-10:22 UT, also observed at lower frequencies by the NRH at 164 MHz and by the DAM as a moving type IV burst (no observation after 12:00 UT) (see sechirh.obspm.fr).

-18-May Microwave bursts 09:19-09:31 UT:  (Ondrejov, ) 3GHz. 11:00-11:00 (2.GHz-800 MHz)

*Caution: see for this event, the comment from Gareth Lawrence in http://cdaw.gov/CME list).
Please note that two other large events have been deliberately included in the movies. The first is a CME seen in the NE from 2002/05/21 21:50 UT (Position 56,135, V 283 439 505 km s−1), and is probably associated with a M1.5 X-ray flare in AR9960, N17E38. The second is a CME seen in the SW from 2002/05/21, a partial halo 23:50 ((CMEP24) PA 230, Width 186, V 1246 1341 1292 km/s) and is probably associated with a C9.7 X-ray flare in AR9948, S25W64. Due to the extents of the CMEs and the positions of their apparent source regions there is reason to believe that either or both might have a small earth-directed component; however both are likely to be overtaken by this third event, which is the fastest of the three. ….. We therefore consider that a single complex ejecta at 1AU is the most likely outcome of these three events.”


In the framework of the  present study, we conclude that the solar event associated with SSC19 is essentially concerned by the “single complex ejecta” i.e. the   solar activity in   May 21-22 .  This event shares the following characteristics :  May 21 21:25 UT: Microwave burst (A), Type II and continuum (B, HIRAISO); May 22:  Microwave burst weak (A);  Continuum (B, HIRAISO ),  and type II  detected by Wind/Waves.