What is the difference between APEC, Mekal, and Raymond-Smith?
Please see the comparisons page for detailed comparisons between the difference codes. The codes themselves are all designed to perform similar calculations. The Raymond & Smith (1977) code, with the most recent (1993) update, is still available, although there is limited documentation (see the NEIline code for a better-documented front end). The code is still used in specific applications since it is extremely fast and can calculate CIE as well as NEI models. The Mekal code is so named because it was developed by Rolf Mewe and Jelle Kaastra. The final ‘l’ comes from Duane Liedahl who calculated the atomic parameters for a large number of iron L-shell ions. The code itself is not easily available, although it is included in XSPEC and could be extracted if desired. However, it is (like the Raymond & Smith code) no longer being updated. Finally, the APEC code (Astrophysical Plasma Emission Code) was developed by Randall Smith and Nancy Brickhouse. APEC uses the APED (Astrophysical Plasma
