Supports· moderateTRN-E017
Cann 2026b: geomagnetic activity does not change plate sensitivity — one artifact route closed
- what the source states
- Testing 12,510 Harvard exposures and 638 Palomar fields against the Kp geomagnetic index, the paper reports no significant trend in reference populations (stellar counts, limiting magnitude) with storm intensity, and constrains atmospheric airglow to ≤12% of the reported POSS-I transient suppression at 95% confidence. It presents this as a general protocol for artifact control in historical plate archives.
- what we infer
- Does the useful negative work that most of this literature does not: it names a specific environmental confounder that could manufacture the temporal patterns, tests it against reference populations, and reports that it does not survive. That does not make the nuclear-window correlation real — it removes one way of making it spurious, which is a different and smaller thing. Recorded here because the artifact-versus-signal question in this case has largely been argued rather than measured, and this is a measurement.
- limitations
- Star counts and limiting magnitude are proxies for plate sensitivity; a confounder acting specifically on transient-like detections rather than on general sensitivity would not be caught by this test.
- Unreviewed preprint from within the proponent-adjacent author network.
- Closes one confounder among many; the Watters et al. critique's central objections concern the null distribution and observation-day normalization, which this does not address.