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Astron. Astrophys. 364, 793-798 (2000)

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3. Data analysis

3.1. Bandwidth and duration

As mentioned above, this type IV-DCIM was also recorded over the range of 800-2000 MHz, which means that it had a bandwidth of more than 2.0 GHz, since it was beyond 3.80 GHz high frequency limit of the BAO spectrometer. It lasted for more than one hour (67 minutes), and had a long decay phase (about 60 minutes); near the intensity peak (around 05:48:12 UT) a peculiar fine structure was detected. This fine structure with a negative picture (Fig. 2 bottom panel) had a bandwidth about 430 MHz between 2.74 GHz and 3.17 GHz, and a total duration over 1.3 seconds.

3.2. Frequency drift and polarization

Fig. 3 shows the average drifting rates of the four branches. The branches of the first U have bigger rates than those of the second one. In addition, as given in Fig. 1, the type IV-DCIM and the fine structure were almost unpolarized all time.

[FIGURE] Fig. 3. Simplified dynamic spectrum of M-burst; the numbers on each branch represent the average magnitudes of drift rates.

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001