Pulse-averaged flux density of pulsar B at 820 MHz (filled circles), as a function of MJD, averaged over BP1 (red), BP2 (blue), the IP (green), and over the entire orbit (black). The flux-density calculation of the individual pulse profiles is based on the radiometer equation, assuming a duty cycle equal to the full pulse width at 10% of the pulse maximum. For the intervals MJD53000–53100 and MJD53100–53200, the flux densities (empty circles) were scaled to 820 MHz, using the spectral indices reported in Sect. 3.3, from observations at 685 and 1400 MHz, respectively. In the interval MJD54200–54300, there were no available data. The dashed lines have been used as guides only.