A three-error echo screen leaves 252 of 702 selected CHIME component pairs compatible with unchanged width and spectral shape

We test necessary conditions for a simple gravitational echo in CHIME/FRB Catalog 2, release 20251231. The model permits a delay and a constant magnification but requires equal intrinsic Gaussian width, spectral index and spectral running. Of 702 component pairs in 296 selected events, 450 fail at least one equality within rectangular ranges of three quoted errors per input. Width alone flags 389 pairs; spectral shape flags another 61. The remaining 252 pairs occur in 146 events. Resolution, separation, band, signal and masking controls leave 24 passing pairs among 50 events with exactly two components. Passing is a weak necessary condition, not lens evidence. Formal errors, fit covariance, component selection and different propagation limit physical claims. We detect no lens and set no abundance bound. A known Catalog 1 candidate passes the screen but has no independent confirmation here. The bundle contains our code, aggregate results, figure and exact input provenance. External catalog rows and record-level outputs remain outside the baseline bundle and can be regenerated.

astronomy · CHIME · fast radio bursts · gravitational lensing · echo screen · conditional interval test · null discovery result