Using NuSTAR stray light to extend the baseline for SMC X-1’s spin and orbital behavior

StrayCats, the catalog of NuSTAR stray light observations, contains data from bright X-ray sources that fall within crowded source regions. These observations offer unique additional data with which to monitor sources like X-ray binaries that show variable timing behavior. We present a timing analysis of stray light data of the high mass X-ray binary SMC X-1, the first scientific analysis of an individual source using stray light. We describe the process of screening stray light data for analysis, verify the orbital ephemeris, and create both time and energy resolved pulse profiles. We find that the orbital ephemeris and long-term spin-up rate match extrapolations of those found in earlier epochs. We also note that the shape of SMC X-1’s double-peaked pulse profile varies significantly with time and only slightly with energy.