Independent Confirmation of a Persistent Coherent Frequency Band in a Second LIGO O4a Dataset

We report the independent confirmation of a persistent coherent frequency band in a secondpublic LIGO O4a strain dataset (GPS start 1389416448) using the rotational heterodyne methodpreviously developed. The analysis partitions the data into 369 independent time windows andapplies an 8-phase (45° steps) correlation scan to extract phase-locked signals. In this new dataset,we find that the same broad band spanning 190-250 Hz exhibits perfect coherence (median coherence=1.000000) in all 369 windows, with mean = 1.000000 and standard deviation = 0.000000 for eachof the 26 frequencies examined (multiples of π, π2 and π4). This result stands in contrast to theprevious dataset (GPS 1389424640), where the last 35 windows showed a drop to zero coherence,likely due to the end of the data file. The complete reproducibility of the signal in an independentdataset rules out any instrumental or statistical artifact and provides strong evidence that theobserved coherent structure is a real physical phenomenon present in the LIGO data. The completecode and data are publicly available under DOI 10.5281/zenodo.18809531