Notes on verification

Corrected 2026-09-06 verification pass: original wording ('astronomy achieved a high level of success in the second half of the first millennium') was vague and dropped BCE. Rewritten near-verbatim from Britannica History of Astronomy, which states: 'Astronomy was the first natural science to reach a high level of sophistication and predictive ability, which it achieved already in the second half of the 1st millennium bce.' Primary source reassigned from Wikipedia History of astronomy (source_id=18) to Britannica History of Astronomy (source_id=872). Also corroborated by HandWiki (source_id=873), World History Encyclopedia Greek Astronomy (source_id=1184), and arxiv 1209.3563 (source_id=1183). Cleared aggregator_dropped_primary_exists flag. [tier=silver indep_score=0.700 clusters=5 claim_tier=notable reviewed_by=verification_pass_2026_09_06]