Workshop CAL TARGETS - What do we aim for in this session? -Cal targets highly depend on he mission. Some targets can be fine for XMM or Chandra, but RXTE or INTEGRAL can not see them. - Also depend on scientific subjects: imaging, timing, energy range,... - Sources with simple physics, because we have to understand what the sources do. - Clusters of galaxies: extended, illuminate large area of the detector, but show spatial structures with spectral differences. - How to connect low energy targets/missions to high energy ones? Problem of different time scales for exposures, e.g. ksec versus Msec. Simultaneous observations are needed. - How to calibrate the energy scale for higher energies of future gratings? Difficult to find astronomical targets with well defined lines. On-board calibration sources or defined fluorescence lines from detector structure or even moveable metal plates could help, (e.g. see copper line for XMM pn). Source Energy Flux keV HZ 43 < 0.2 Bright Sirius B < 0.2 HZ43 /10 RXJ1856 < 1 Faint Simplicity Var WD WD No No No No Yes Yes Extend Lines Point Point Point 1' Point Point Point No Point Point Yes No Yes Yes Yes Yes Point Point, jet Point Cont Cont Cont Cont Lines Cont Lines Lines Lines Lines Cont purpose