The Photographer's Ephemeris: Sun and Moon Position Tool for Geolocation OSINT

When image claims hinge on a photo's location or timestamp, solar geometry comes into play. The Photographer's Ephemeris, or TPE, is the tool for that. Most investigators know SunCalc for quick sun checks. TPE is ideal for map-centric workflows and detailed planning, offering clean directional overlays.

What The Photographer's Ephemeris Does

The Photographer's Ephemeris is an interactive map that shows precise sun and moon position for any location and date. It provides values OSINT analysts care about for light-based verification: azimuth, elevation, rise and set direction, and timing windows such as golden hour. The values are placed directly onto a map so you can reason spatially.

The spatial view is the key feature. TPE draws sun and moon rise/set azimuths as directional lines over the map, with satellite imagery. If you are comparing a building shadow, a ridgeline, a coastline, or a road orientation to expected lighting, those lines are immediately useful. You do not need to mentally translate a compass bearing into how it would look on the ground.

TPE is available as a free web app, with iOS and Android apps for field use. It was built for photographers planning shoots, but the design makes it valuable in geolocation and verification work. Investigators use it to test whether observed light conditions in an image are compatible with a claimed place and timestamp.

Compared with simpler calculators, TPE focuses on how light will hit an exact spot on a specific date. Sun and moon positions, elevation, azimuth, and times are provided. The app is a strong fit for shadow analysis.

Geolocation OSINT Applications

Verifying Photo Locations with TPE

Verifying photo locations is a key OSINT use case. Shadow direction in a photo can be matched to sun azimuth at a given time and place. If a post claims a photo was taken in central Madrid at 09:00, but shadows suggest a different sun bearing, the claim is questionable.

Filtering Locations with Shadow Angles

TPE helps when the shadow angle is known but not the location. It becomes a filtering tool. Test candidate areas to see if the camera was here, on this date, at this time, and if shadows align with the image; if not, eliminate that location.

Directional Clues in Urban Areas

This is especially useful in cities or mountains. Features such as roads, rooftops, towers, fences, and poles provide directional clues. A vertical object and a shadow in an image can give an approximate azimuth; compare it to TPE's solar data.

Cross-Referencing with Google Maps

Using TPE and Google Maps satellite view together is a powerful approach. TPE provides light geometry; Google Maps provides terrain and environment. They can be used to test if visible features match the calculated sun position; often, this is stronger than using either alone.

TPE vs SunCalc

SunCalc still works great for quick checks. It loads fast and gives you a rough idea, often that's all you need.

The Photographer's Ephemeris (TPE) shines when you need more data. TPE provides civil, nautical, and astronomical twilight, moon phases, and golden hour. For OSINT, those details matter when images are supposedly taken near dawn, dusk, or under moonlight.

Claims might pass a crude daylight test but fail when twilight or moon position are considered.

TPE's design helps when checking multiple sites or dates. The map-centric approach makes it easy to compare and maintain context.

The Photographer's Ephemeris 3D (TPE3D) takes analysis to the next level with 3D terrain. Raw solar azimuth isn't everything; mountains, ridgelines, and buildings can block light and change illumination. For precise analysis, especially in valleys or cities, a 3D simulation makes a difference.

TPE3D can answer questions like "Does sunlight hit this façade at that time?" SunCalc can't match that capability.

Practical Workflow

A sensible workflow starts before using TPE. First, obtain a geographic area from other OSINT signals, such as language on signs, architectural style, visible transit infrastructure, vegetation, weather, plate formats, and prior geotagged posts.

TPE works best when narrowing down possibilities, not inventing them from scratch. Next, determine the shadow direction from an image by selecting a vertical feature, such as a pole, building corner, tower, or person, and measuring the shadow direction, which can be aided by road edge or wall alignment.

The goal is to eliminate scenarios with rough angles. Compare the shadow direction to TPE's solar azimuth to identify candidate locations and date/time ranges. For example, if the observed shadow indicates southeast and TPE indicates southwest, eliminate that location.

This process saves time and removes impossible options. Combine TPE with map and infrastructure checks using Google Maps or satellite basemaps, and verify terrain alignment. Use Street View to validate camera perspective, road curvature, and building placement.

Overpass Turbo queries infrastructure, including schools, rail lines, fuel stations, power features, and religious buildings. TPE sharpens other tools, particularly when lighting geometry is a factor.

For OSINT analysts familiar with SunCalc, TPE may not be the fastest initial resource; it's often more effective as a second step. However, when light, shadows, moon position, or terrain-blocked sun are relevant, TPE provides a rigorous, map-based test.