Nobeyama Radioheliograph Event 19980423_0541

EventID : norh19980423_0541
Observer : J. Sato and T. Yokoyama
Keyword : flare
Start : 1998-04-23 05:36:18
End : 1998-04-23 06:44:56#
Peak : 1998-04-23 05:41:39
Maximum Correlation @17GHz (x10^-4) : 2128
Position : S13E91 or S18E91(SXT PFI center)
GOES : X1.2
NOAA Number : 8210

This event is important !!

1) Full data set taken with the NORH, SXT, HXT. Especially NORH 100 msec data was obtained,

2) Strong brightness in radio map means non-thermal emission.

3) Number of SXT quarter images is large due to special table plan (thanks to SXT chief observers). Study of coronal structure in flare is possible.

4) Due to limb occulting, detailed study of loop top structure is possible.

5) One of few example of LDEs which are synthesized in YOHKOH HXT.


NRO 17/34 GHz correlation plot
Rapid increase of 17 GHz correlation data means that 17 GHz source appeared transiently. It corresponds that radio foot point sources may be occulted. If so, many images at many spikes may give us detailed understanding of energy release or acceleration site.


NRO Polarimeter Data (9.4 GHz data should be corrected)


17GHz Radio Map movie


SXT PFI(quarter) movie
SXT images show continuous evolution of loops during preflare and impulsive phase in north region. Flareing region is south. Brightest part can be seen near the limb and its height is lower than expanding loops. Obvious footpoint brightnigng or elongated loop structure could not be seen in begining of the flare. Therefore, limb may be occulted.

SXT PFI(Full) movie


Coaligned NORH and SXT images before impulsive phase. Left: SXT(contour) and NORH(17GHz). Middle: NORH(17GHz). Right: SXT (Al12). Brightest region is not flaring region. In the NORH, faint coronal structure (south) shows curious structure such like blobs. movie


HXT 4 channel plot

HXR time profile shows gradual behavior and its spectrum is soft. In the begining of flare, M1 band time profile shows less spike structure compared with L band. Moreover, its count is high than usual background counts (1-2 counts/SC) .

HXT L band Images ( 157X157^M arcsec) movie (grid line is tentative)
HXT L band source shows obivious source motion from south to north direction.
Near the end of this flare, HXT L band source shows two separated component. One exists in higher corona.


Coaligned SXT(color) and HXT(contour) Images. Left: L band (5:40:34-5:40:54), Middle: M1 band (05:40:34-05:40:54), Right: M2 band (05:39:54-05:41:14), SXT(be filter) observation time is 05:40:36.

Last updated on April 27, 1998