Abstract We present a new sub-class of type III solar radio burst at the high frequencies around 6.0 GHz. In addition to a descending and an ascending branch on the dynamic spectrum, it has an inverted morphology different from the simple type U-burst. We call it ``partial N-burst'' because it is interpreted as the known N-burst minus its first branch. The partial N-burst presented here was detected among a reverse slope type III (RS-III) burst group prior to the type V solar radio continuum and was simultaneously recorded by two spectrometers at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC, 5.20–7.60 GHz) and at Purple Mountain Observatory (PMO, 4.50–7.50 GHz) on 1999 August 25. After the N-burst and M-burst, the partial N-burst is a third piece of evidence for a magnetic mirror effect in solar radio observation, when the same electron is reflected at a pinched foot of a flare loop.

Keywords Sun: radio radiation --- Sun: magnetic fields

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