Diagonal Star Tables

Definition

A diagonal star table is an Egyptian timekeeping chart painted inside the lid of a Middle Kingdom coffin. It records which decan stars — the star groups that mark night hours — rise during each hour of the night, across all 36 ten-day "weeks" (decades) of the civil year. Laid out as a 36 × 12 grid, it shows a tell-tale diagonal pattern: the same decan slides forward by one hour every decade. Such tables are also called diagonal calendars or coffin-lid star tables.

In Tradition

Egyptologists — following Neugebauer and Parker's reconstruction (*Egyptian Astronomical Texts* Vol I, 1960) and Clagett's consolidation (*Ancient Egyptian Science* Vol II) — read the diagonal star tables as the earliest surviving decanal-clock system. They were Egypt's way of telling the hours of the night by the stars, and they anchored Egyptian timekeeping for more than a thousand years.

In Practice

Egyptian priest-astronomers used these tables to tell the time; the dead used them too. Painted inside a coffin, a diagonal star table was funerary equipment, so the noble buried there could keep ritual time in the afterlife. The earliest near-complete example is Clagett's Document III.11 — the Meshet coffin lid (Asyut, Dynasties 9-10, c. 2154-1783 BCE; Cairo Museum 28118). It holds an almost-whole decanal clock in a 40-column grid: columns 1-36 give the twelve hourly decans for each ten-day decade of the year, from Akhet I.1 through to the last decade of Shemu IV; column 40 gives the twelve decans for the epagomenal days; columns 37-39 carry a decanal list. Read across the grid, each decan name steps diagonally downward — the visual signature that gave these tables their modern name.

Historical Origin

The earliest example is the Meshet coffin (Asyut, Dynasties 9-10, c. 2154-1783 BCE; Cairo Museum 28118) — first described by Daressy (1900, ASAE I), with the full text published by Lacau (1906, Catalogue général), analyzed by Pogo (1932), and given its standard edition in Neugebauer-Parker, EAT Vol I (1960). Clagett treats it in *Ancient Egyptian Science* Vol II, Document III.11 (1995). Belmonte and Lull also discuss the decanal arrangement on the Senenmut tomb ceiling (1473 BCE).

Definition

In Tradition

In Practice

Historical Origin

Further Reading