A long-term error in the SSCWeb implementation of the Tsyganenko 1987 and 1989 external field models has been recently identified while installing the Tsyganenko 1996 model and is now corrected for all models.

The error could produce noticeable effects in both the computed local field (usually <2% but occasionally larger) and in field line tracings (usually <0.3% in traced latitude and longitude but occasionally larger), particularly from spacecraft like Geotail deeper in the magnetosphere.

Users who have relied on highest-fidelity field-line tracings from such spacecraft may want to rerun selected cases to determine if specific changes are significant to their research expectations of SSCWeb. We greatly apologize that any error of this nature was not previously detected in our testing procedures and corrected.