8.1.1. The SPEX Atomic Code & Tables (SPEXACT)

The SPEX package is a spectral fitting program with integrated models that are mostly based on one atomic database and a set of routines to calculate all the atomic processes in the plasma. Although the development of the atomic database and code is performed mostly in parallel with the other SPEX development, it can sometimes be confusing which version of the atomic database was actually used in an analysis. Especially after the major update of the atomic database in SPEX 3.0 and the option to calculate models using the ’old’ database and routines from SPEX 2.0, there is a need to name and version the ’core’ routines of SPEX separately. This has become SPEXACT (SPEX Atomic Code & Tables). In principle, models calculated using the same SPEXACT version should produce the same results.

Please note that the SPEXACT database and routines are an integrated part of SPEX and are not distributed separately. Main version number definition

SPEXACT v1: Is essentially the MEKAL model that was developed in the 1980’s and is distributed with Xspec. This model is no longer developed or supported, but can be regarded as the first version of SPEXACT. It is no longer included in SPEX.

SPEXACT v2: In SPEX version 1 & 2, the original MEKAL model was extended and updated into SPEX. The version number of this SPEXACT version is the same as the version number of SPEX when it was released. For example, the SPEXACT version in SPEX version 2.04.00 is also 2.04.00. In SPEX version 3, these routines are still the default and are used in var calc old mode.

SPEXACT v3: These are the newly developed atomic database and corresponding routines that were officially released with SPEX version 3.00.00. This database and its routines are not (yet) the default in SPEX, but can be used when the var calc new command is given. The second number in the SPEXACT version is the same as the SPEX version it was released in. The third number can in principle be different from the SPEX version and indicates the minor version of the database.