NIFTY-LS: Fast and Accurate Lomb–Scargle Periodograms Using a Non-uniform FFT

We present NIFTY-LS, a software package for fast and accurate evaluation of the Lomb–Scargle periodogram. NIFTY-LS leverages the fact that Lomb–Scargle can be computed using a non-uniform fast Fourier transform (NUFFT), which we evaluate with the Flatiron Institute NUFFT package (FINUFFT). This approach achieves a many-fold speedup over the Press & Rybicki method as implemented in ASTROPY and is simultaneously many orders of magnitude more accurate. NIFTY-LS also supports fast evaluation on GPUs via CUDA and integrates with the ASTROPY Lomb–Scargle interface. NIFTY-LS is publicly available at https://github.com/flatironinstitute/nifty-ls/.