Calibrated W1 image rings of HD 166191 are 26% brighter in 2023–2024 than in 2014–2017

We test whether the late infrared images of HD 166191 returned to their earlier level after a known increase. We use 518 public NEOWISE image files and measure rings outside the saturated source center. Eight nearby stars per band were selected from AllWISE before image flux inspection. Each scan direction has its own reference level. The calibrated W1 mean in three visits in 2023–2024 is 1.2635 times the 2014–2017 reference. Individual late ratios are 1.2355 to 1.2803. The reference visit RMS is 0.0192. Removing one comparison at a time gives mean ratios of 1.2610 to 1.2825. Available ring, sky, center, and detector-position checks retain a positive change. Two comparison stars show large changes and remain in the calibration. Enlarged masks leave too few comparisons. Strict frame-quality cuts leave insufficient reference coverage. W2 has only one accepted primary late visit and no accepted comparison test light curves. Saturated catalog fits give different late amplitudes. The result establishes an image-ring change under local star calibration. It does not establish a 26% total-flux increase. The physical interpretation requires stable relative image-wing response. We preserve lossless crops, source checksums, catalog queries, all results, figures, code, and offline reproduction instructions.

HD 166191 · NEOWISE · infrared photometry · saturation · image wings · comparison stars · debris disks · reproducible data