astronomical day

Your correspondent DX. is mistaken in supposing that "foreigners ordinarily commence the astronomical day at midnight."

From Notes and Queries, Vol. IV, Number 105, November 1, 1851 A Medium of Inter-communication for Literary Men, Artists, Antiquaries, Genealogists, etc. by Various

One of the objects of the third resolution is to make the new universal day coincide with the civil day rather than with the astronomical day.

From International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day. October, 1884. Protocols of the Proceedings by Various

Since the civil day begins 12 hours before the astronomical day and ends 12 hours before it, A.M. of a new civil day is P.M. of the astronomical day preceding.

From Lectures in Navigation by Ernest Gallaudet Draper

The astronomical day commences at noon of the civil day of the same date.

From Lectures in Navigation by Ernest Gallaudet Draper

The civil day always commences at the midnight preceding this astronomical day.

From Notes and Queries, Vol. IV, Number 105, November 1, 1851 A Medium of Inter-communication for Literary Men, Artists, Antiquaries, Genealogists, etc. by Various