All-sky, broadband, coherent searches for gravitational-wave pulsars are
computationally limited. It is therefore important to make efficient use of
available computational resources, notably by minimizing the number of
templates used to cover the signal parameter space of sky position and
frequency evolution. For searches over the sky, however, the required template
density (determined by the parameter-space metric) is different at each sky
position, which makes it difficult in practice to achieve an efficient
covering. Previous work on this problem has found various choices of sky and
frequency coordinates that render the parameter-space metric approximately
constant, but which are limited to coherent integration times of either less
than a few days, or greater than several months. These limitations restrict the
sensitivity achievable by hierarchical all-sky searches, and hinder the
development of follow-up pipelines for interesting gravitational-wave pulsar
candidates. We present a new flat parameter-space metric approximation, and
associated sky and frequency coordinates, that do not suffer from these
limitations. Furthermore, the new metric is numerically well-conditioned, which
facilitates its practical use.Comment: 19 pages, 20 figure
