PSR B1821−24. Light curves based on (a) ASCA GIS (0.7–10 keV), (b) RXTE PCA (2–16 keV), (c) Jodrell Bank radio (1408 MHz) observations, using timing ephemeris B1821−24J. The ASCA light curve is labeled in total counts per bin (at 48 bins per period), the RXTE light curve in counts per second per bin (at 100 bins per period) with 1 σ errors indicated. The instrumental broadening in the radio profile amounts to about 0.1 in pulse phase. Note that the zero point of the phase of this ephemeris used in this figure is different from the one used in Fig. 2.