StrayCats: A catalog of NuSTAR Stray Light Observations

We present StrayCats: a catalog of NuSTAR stray light observations of X-ray sources. Stray light observations arise for sources 1--4$^{\circ}$ away from the telescope pointing direction. At this off-axis angle, X-rays pass through a gap between optics and aperture stop and so do not interact with the X-ray optics but, instead, directly illuminate the NuSTAR focal plane. We have systematically identified and examined over 1400 potential observations resulting in a catalog of 436 telescope fields and 78 stray light sources that have been identified. The sources identified include historically known persistently bright X-ray sources, X-ray binaries in outburst, pulsars, and Type I X-ray bursters. In this paper we present an overview of the catalog and how we identified the StrayCats sources and the analysis techniques required to produce high level science products. Finally, we present a few brief examples of the science quality of these unique data.