A line needs a minimum 3.80% flux tolerance for 16 V488 Per visits with a scan season offset in 2014–2024

One variable source with a fixed two-band spectrum plus constant light gives a line in flux space. We test this model in 16 selected NEOWISE visits of V488 Per from 2014 to 2024. We allow a free repeatable offset between scan seasons. We use 137 paired exposures and 12 control stars selected from static catalogue values. Each measured W1 and W2 flux can move independently within a common relative bound. The smallest bound that permits the model is 3.7996%. Direct slope bounds and linear programming agree within 1.3e-10 in fractional tolerance. Without the season offset, the minimum is 5.5585%. These bounds are geometric. They are not measured errors or confidence limits. A separate Gaussian test gives a conditional conservative reference p = 0.200 with an independent 3% visit error floor in each band. It gives p = 0.000344 with a 2% floor. At a 3% floor, removal of the season offset gives p = 0.00762. These probabilities hold the estimated covariance fixed. They do not prove a fixed dust spectrum. An exploratory model gives a later W2 offset of +5.18 mJy at the same W1 flux. All four visits from 2021 onward use winter scans. A changing scan effect can imitate this result. The package preserves source responses, exact queries, code, selection audits, covariance matrices, numerical checks, figures, and instructions for a clean offline replay.

V488 Persei · V488 Per · extreme debris disk · NEOWISE · infrared variability · two-band spectrum · flux tolerance · calibration covariance · reproducible astronomy