Hongao Wu

Microwave type III bursts and pulsation groups

We analyse 22 continuous microwave reverse slope (RS) type III and 21 microwave pulsation groups observed by the Purple Mountain Observatory (PMO) spectrometer over the frequency range of 4.5-7.5 GHz from 1999-2003. The RS type III groups have an average of 12 bursts per group, a mean duration of 0.1-2 s around 6 GHz, a mean quasi-period of 2.0 +/- 0.6 s and a mean drift rate of 7.0 GHz s(-1). The shortest quasi-period is measurable down to 0.05 s thanks to the high time resolution of this instrument. The microwave pulsation groups have an average of 22 events per group, a mean duration of 3-4 s and a mean quasi-period of 3.7 +/- 1.1 s. The RS type III bursts have the same quasi-period as the upward type III bursts documented before. We discuss two possible origins of the quasi-periodicity of type III bursts. One is the quasi-periodic process in magnetic reconnection at the same site, and the other is spatially unresolved stochastic processes in solar flares.

Some observed results of solar radio spectrometer at 4.5-7.5 GHz

A new instrument of broadband solar radio spectrometer working at waveband 4.5-7.5 GHz was developed at Purple Mountain Observatory for Solar Maximum 23. Some new results of spectral observation have been obtained since August 1999. Two typical type III mu bursts with rich fine structures are presented and some interesting features discussed.

Observation of the 1997-03-09 total eclipse at 8.6 mm

COPY THE ORIGINAL Analysis of the total eclipse observation of 1997 March 9 at wavelength 8.6 mm, shows that, at this wavelength, the solar radius is 1.012 R., the total flux density is 2540 sfu, the mean brightness temperature of the solar disk is 9632 K, and the brightness temperature distribution shows limb brightening at the inner edge of the solar disk, the average brightness at 0.936-0.992 R. being 9.7% above the central brightness.