A class X1.5 flare started on the solar limb at 00:43 UT on 21 April 2002 , which was associated with a CME observed at 01:27 UT by LASCO C2 .
The coordinated analyses of this flare include TRACE 195 Å images and SUMER spectra in lines of Fe XXI , Fe XII , and C II .
We find that : 1 ) The flare began with a jet seen by TRACE , which was detected by SUMER in the C II line as a strong brightening with blue shifts up to 170 km s ^ { -1 } .
At that time only weak emission was detected in Fe XII and Fe XXI .
2 ) Subsequently , a weak looplike brightening started south of the jet , moving outwards with an average speed of about 150 km s ^ { -1 } .
The SUMER spectra responded this moving loop as separatingly brightenings , visible only in the Fe XXI line .
The southwards moving component contains red- and blue-shifted emission features and has an apparent speed of \sim 120 km s ^ { -1 } .
The absence of signatures in Fe XII and C II lines indicates that the moving weak loop seen by TRACE corresponds to the emission from very hot plasma , in a blend line in the 195 Å bandpass due to Fe XXIV formed at T > 10 MK .
3 ) The trigger mechanism of the flare and associated CME can be interpreted in the same way as that proposed by Wang et al .
( 13 ) for an event with similar initial features .