Daytime Venus records against the Venus cycle

Dates of '太白晝見'/'太白經天' articles placed on the 583.92-day synodic cycle: the share within ±90 days of inferior conjunction, and the Rayleigh Z.

583.7days recovered (Venus: 583.92)

Key point

Four centuries of articles reproduce a planet's period to within 0.04%. The strongest quantitative support for treating the Sillok's astronomical articles as accumulated observation — and, by analogy with the law of evidence, a case for weighing observational and evaluative records differently.

Formula: Phase = (record JD − conjunction JD) mod 583.92, conjunctions from DE406; a uniform distribution gives 30.8% within ±90 days.
How to read it: About 66% of some 2,900 record days cluster within ±90 days of conjunction and almost none within ±6 days, as daytime visibility requires. At least this kind of record carries the signal of real observation; why things were recorded is not something this test can tell.
Caveats: Several articles on one day count as one day. Phase is the difference between the article date (JDN) and the conjunction time (TT, continuous). The effect of varying record density across reigns on the phase distribution was not tested separately.

Reliability card: externalExternal match — compared with an astronomical computation
Record days: 2,937. Of these, 65.8% fall within ±90 days of inferior conjunction (uniform: 30.8%) and 0.17% within ±6 days (uniform: 2.1%). A period scan over 300–900 days peaks at 583.7 days with Rayleigh Z = 1,117, 0.04% from the 583.92-day synodic period.

Rayleigh Z across trial periods 300–900 days; the band marks the 583.92-day synodic period.

Record days by phase relative to inferior conjunction (0). 66% lie within ±90 days (darker); the conjunction itself is nearly empty.

Item	Value
Record days	2,937
Share within ±90 days of inferior conjunction	65.8%
Share within ±6 days of inferior conjunction	0.17%
Best period from the period search (days)	583.7
Rayleigh Z at 583.92 days	1,092.5
Rayleigh Z at the best period	1,117.1

Download CSV: c_venus.csv