Cross-calibration of the X-ray instruments onboard the<i>Chandra</i>, INTEGRAL, RXTE,<i>Suzaku, Swift</i>, and XMM-<i>Newton</i>observatories using G21.5โ0.9
Cross-calibration of the X-ray instruments onboard the<i>Chandra</i>, INTEGRAL, RXTE,<i>Suzaku, Swift</i>, and XMM-<i>Newton</i>observatories using G21.5โ0.9
Context. For many years, X-ray astronomy missions have used the Crab nebula as a celestial calibration source for the X-ray flux and spectral shape. However, the object is often too bright for current and future missions equipped with instruments with improved sensitivity.