Return the telescope effective area in square cm averaged over the given energy band and at a specified position in the telescope field of view. Vignetting by the X-ray baffles and by the reflection grating spectrometer is taken into account. The state variable AccuracyLevel determines the scheme to be used to calculate the effective area:
| Accuracy Level | scheme | description |
| NORMAL | library | the effective area at any position in the field of view is calculated from an on-axis effective table and from a set of vignetting tables provided in the CCFs. The vignetting tables are normalized to one on-axis and are provided as a function of the off-axis angle for energies ranging from 100 eV to 15 keV. Interpolations in energy and field angle are performed to provide the value of the vignetting function at the requested energy and field position. This value is then multiplied by the on-axis effective area tabulated in the CCF. For the MOS camera, the results is then multiplied by the vignetting law of the reflection grating assembly. |