  We discuss properties of a Type IV burst, which was observed on 2017
September 6, as a result of the powerful flare X 9.3. At decameter wavelengths
this burst was observed by the radio telescopes STEREO A, URAN-2, and NDA at
frequencies 5 - 35 MHz. This moving Type IV burst was associated with a coronal
mass ejection (CME) propagating in the southwest direction with a speed of 1570
km/s. The maximum radio flux of this burst was about 300 s.f.u. and the
polarization was more than 40%. In the frequency range of 8-33 MHz it continued
for more than 2 hr. For STEREO A the associated CME was behind the limb, its
longitudinal angle was about 160 degrees. This moving Type IV burst was
observed by STEREO A at frequencies of 5-15 MHz in spite of the low sensitivity
of STEREO A. This means that the radio emission directivity of a Type IV burst
is rather wide. Assuming the plasma mechanism of Type IV radio emission we
derived the plasma density distribution in the CME core at distances of 5.6 Rs
and 9.8 Rs and its mass to be about 10^16 g . It is planned that the minimum
perihelion of the Parker Solar Probe (PSP) spacecraft will be at about 9 Rs. So
we discuss in what conditions PSP will be in if it crosses a similar CME core.
