Image Details
Caption: Fig. 1.
VLA snapshot maps of intense nonthermal activity at 400 cm wavelength taken in 10 s intervals on 1998 March 8 at the times indicated. They are superposed on SOHO EIT images taken in the 195 Å line of Fe XII, formed at ﹩1.5\times 10^{6}﹩ K, within a few minutes of the VLA snapshot maps. The field of view is ﹩30^{\prime }\times 30^{\prime }﹩. The contours denote levels of equal brightness temperature Tb corresponding to ﹩T_{b}=1,\: 2,\: 3,\: ...,\: 10\:\times 10^{6}﹩ K at 19:14:24 UT and 21:14:04 UT, ﹩T_{b}=5,\: 10,\: 15,\: ...,\: 35\:\times 10^{6}﹩ K at 21:32:34 UT, and ﹩T_{b}=10,\: 20,\: 30,\: ...,\: 90\:\times 10^{6}﹩ K at 22:20:55 UT. The arrow on the image taken at 19:14:24 UT shows the location of an EUV brightening detected on the EIT image 10 s earlier. The 400 cm radiation remains at the same radial distance from the solar surface, probably denoting the level at which the plasma frequency is close to the observing frequency of 74 MHz, but the radio bursts appear to move along the archlike or looplike structure that probably describes otherwise invisible, large‐scale magnetic fields in the corona. They may be linked to one of the active regions denoted by bright EIT features.
© 1998. The American Astronomical Society. All rights reserved. Printed in U.S.A.