Coordinate Invariant Limits of the Reisner-Nordstrom spacetime

Certain special limiting cases of the Reisner-Nordstrom spacetime have been of interest due to potential applications to string theoretic models. Here we review a formal limiting technique based on Cartan-Karlhede invariants and present a small extension which allows for its application to spacetimes which simultaneously are non-vacuum and non-conformally flat. We apply this technique to recover the familiar extremal limit of the Reisner-Nordstrom spacetime, as well as several other novel limits.