Nancay filename order puts the lower frequency second in 33 of 48 unequal pairs with gaps of 1 to 300 ms

We test the order of observed spectral centers in public Nancay data for FRB 20220912A. Filename times resolve short gaps that the rounded summary times cannot resolve. After exact-key duplicate removal, 52 adjacent pairs with gaps greater than 1 ms and at most 300 ms give 33 decreases, 15 increases and four ties in 21 sessions. The lower fraction among unequal pairs is 68.75%, with a nominal 95% session-bootstrap range of 56.60% to 80.56%. Exact whole-session reversal gives a one-sided probability of 0.00885. Nonoverlap and equal-search-DM cuts retain the direction. Band-edge and high-signal cuts give wider uncertainty. Gaps of 5 to 1800 seconds give equal counts in both directions. A restricted simultaneous-emission model needs residual dispersion measures above 35 to explain the decreasing pairs by cold-plasma delay alone. This scale check depends on the time reference and center interpretation. Published FAST work reports the same direction, but we do not reanalyze those data. Burst components, detector selection and unresolved duplicates remain possible. No new source, planet or emission mechanism is established. Code, aggregate evidence, input hashes and an external retrieval recipe are included.

astronomy · FRB 20220912A · Nancay · frequency drift · filename timing · conditional reversal · instrument selection