TDAS versus SPEDAS: Some clarification for long-time TDAS users

With the latest release of the THEMIS data processing tools, we have introduced a new software product called SPEDAS: the Space Physics Environment Data Analysis Software. For those of you who may be wondering what happened to TDAS, or what software you should download to continue analyzing THEMIS data, we would like to clarify the relationship between SPEDAS and TDAS.

The previous versions of the THEMIS analysis tools were released under the name TDAS (THEMIS Data Analysis Software). This package included a number of command-line and graphical user interface (GUI) data loading and analysis tools developed specifically for THEMIS, plus a number of more general-purpose tools such as TPLOT, HTTP file download tools, coordinate transforms, and analysis routines.

As TDAS became more widely used, some other projects (most notably, ERG and IUGONET) expressed an interest in adding support to TDAS for their missions and other data sets. We recognized the value in making the tools we've already developed more accessible to the rest of the community, so that each project wouldn't have to reinvent the wheel by developing their own file download code, GUI tools, and plotting software. In support of this goal, we began a software development effort to separate the GUI and general-purpose tools and utilities from the parts of the system that were specific to THEMIS. We now use the name SPEDAS to refer to the software product comprising the general-purpose tools, GUI, and plugin support framework itself. The name TDAS now refers to the THEMIS-specific tool set, which is now just another plugin module that uses the general purpose SPEDAS framework.

With the release of SPEDAS 1.00 and TDAS 9.0, we have come a long way toward meeting this goal, yet our work in that area is not quite done. There are still a few parts of SPEDAS that depend on THEMIS code (particularly, the GUI "Data Analysis" panel). We are working on untangling those last few dependencies for future SPEDAS releases. In the future, we expect that SPEDAS and TDAS (and other plugins) will have independent release schedules. For convenience, we will always make available a "bundled" release including SPEDAS, TDAS, and other available plugins. In the future, we will also offer a TDAS-only download that can be dropped into an existing SPEDAS installation.

For this release, we are only offering the software bundle that includes SPEDAS 1.00 and TDAS 9.0. This applies to all the download options (source code, IDL sav file, and IDL Virtual Machine executable releases).

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