SIMBAD references

We report on the detection of a burst from FRB 180916 by realfast/Very Large Array and present software for interpreting fast radio bursts (FRB) periodicity. We demonstrate a range of periodicity analyses with bursts from FRB 180916, FRB 121102 and FRB 180814. Our results for FRB 180916 and FRB 121102 are consistent with published results. For FRB 180814, we did not detect any significant periodic episodes. The realfast-detected and other high-frequency bursts for FRB 180916 tend to lie at the beginning of the activity window, indicating a possible phase-frequency relation. The python package frbpa can be used to reproduce and expand on this analysis to test models for repeating FRBs.