Number 13-class battleship Number 13-class battleship The "Number 13"-class battleship was a planned class of four fast battleships to be built for the Imperial Japanese Navy (IJN) during the 1920s. The ships never received any names, being known only as "Numbers 13–16". They were intended to reinforce Japan's "eight-eight fleet" of eight battleships and eight battlecruisers after the United States announced a major naval construction program in 1919. The "Number 13" class was designed to be superior to all other existing battleships, planned or building. After the signing of the Washington Naval Treaty in 1922, they were cancelled in November 1923 before construction
13 Monocerotis 13 Monocerotis 13 Monocerotis (13 Mon) is a class A0 Ib (white supergiant) star in the constellation Monoceros. Its apparent magnitude is 4.5 and it is approximately away. 13 Mon lies within the Monoceros OB1 stellar association, halfway between the Rosette Nebula and NGC 2264, at a distance of about 780 parsecs. It is surrounded by a small reflection nebula listed as Van den Bergh 81 (VdB 81). 13 Monocerotis has been used as a standard star for the A0 Ib spectral class. Extended photometry of 13 Monocerotis from 1997 to 2000 shows irregular variation of up to 0.04 magnitudes