# Department of Defense master clock

> atomic master clock for the U.S. Department of Defense

**Wikidata**: [Q5260243](https://www.wikidata.org/wiki/Q5260243)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Department_of_Defense_master_clock)  
**Source**: https://4ort.xyz/entity/department-of-defense-master-clock

## Summary
The Department of Defense master clock is the official atomic master clock for the U.S. Department of Defense. Located in the United States, it serves as a precise timekeeping standard and functions as an output device for presenting information in visual form. In the event of a failure, its duties are assumed by the US Naval Observatory Alternate Master Clock.

## Key Facts
- **Official Title:** Department of Defense master clock
- **Primary Function:** Atomic master clock for the U.S. Department of Defense
- **Location:** United States
- **Classification:** Instance of an atomic clock, display device, and geographic entity
- **Operational Status:** Active; designed to be replaced by the US Naval Observatory Alternate Master Clock during failover events
- **Visual Function:** Serves as an output device for the presentation of information in visual form
- **OpenStreetMap ID:** Node 11729255970
- **Commons Category:** Department of Defense master clock
- **Wikidata Description:** Atomic master clock for the U.S. Department of Defense

## FAQs
### Q: What is the Department of Defense master clock?
A: It is the atomic master clock designated for the U.S. Department of Defense. It provides the standard time reference for the department and is located in the United States.

### Q: Is the Department of Defense master clock a physical location?
A: Yes, structured data classifies it as a geographic entity with a specific OpenStreetMap node ID (11729255970). It is also categorized as a display device.

### Q: What happens if the master clock fails?
A: The system is equipped with a failover mechanism. If the primary clock fails, it is replaced by the US Naval Observatory Alternate Master Clock.

### Q: How is the clock classified technically?
A: It is classified as an instance of an atomic clock and a display device. As a display device, it functions as an output mechanism for visual information.

## Why It Matters
As the designated atomic master clock for the U.S. Department of Defense, this entity serves as the central timekeeping standard for one of the world's largest military organizations. Its primary significance lies in its role as the definitive source of time for all Defense Department operations, ensuring synchronization across complex systems.

The existence of a specific failover replacement—the US Naval Observatory Alternate Master Clock—highlights the critical nature of this infrastructure; timekeeping is important enough to require immediate redundancy in the event of a failure. Furthermore, its classification as a "display device" indicates that it provides a visual output of this atomic time data, bridging the gap between high-precision atomic measurement and observable information. By defining a standard time, the clock facilitates coordination, secure communications, and operational logistics throughout the United States military infrastructure.

## Notable For
- **Official Timekeeping:** Serves as the exclusive atomic master clock for the entire U.S. Department of Defense.
- **Visual Output:** Unlike abstract timekeeping standards, this entity is explicitly classified as a display device, meaning it presents information in a visual form.
- **Failover Design:** Uniquely linked to a specific backup system, the US Naval Observatory Alternate Master Clock, for immediate failover continuity.
- **Geographic Specificity:** While many timekeeping services are virtual, this entity is tied to a specific geographic location within the United States (OpenStreetMap Node 11729255970).

## Body
### Definition and Classification
The Department of Defense master clock is an atomic clock located in the United States. In structured knowledge bases, it is defined as an instance of three distinct classes: an atomic clock, a display device, and a geographic entity. Its core function is described as serving as the "atomic master clock for the U.S. Department of Defense."

As a **display device**, it acts as an output device for the presentation of information in visual form. This distinguishes it from purely internal computing clocks, indicating it is a visible interface or readout of precise time.

### Operational Continuity
The system is designed with robust contingency protocols. Structured data indicates that the entity is "replaced by" the **US Naval Observatory Alternate Master Clock**. This relationship is qualified by the "failover" context, meaning the alternate clock takes over the master responsibilities should the primary Department of Defense master clock cease to function.

### Identifiers and Metadata
The entity is cataloged under several unique identifiers across academic and web platforms:
- **Wikimedia Commons:** Hosts an image file located at `Usno-mc.jpg` and maintains a category specifically named "Department of Defense master clock."
- **OpenStreetMap:** The physical entity corresponds to Node ID `11729255970`.
- **Legacy IDs:** It holds a Freebase ID (`/m/0b7wy`) and a discontinued Microsoft Academic ID (`2777910194`).
- **Wikipedia:** It has an English Wikipedia entry with the title "Department of Defense master clock."