"Shibukawa Shunkai’s letters: A life dedicated to the Jokyo calendar", a newsletter article on the work of Shibukawa Shunkai (b. 1639) - first official astronomer of the Tokugawa Shogunate, Japan @NDLJP_en https://t.co/uFhFr4kUHw https://t.co/205mgVdq1Y