PNT Toolkit · GPS-Denied Positioning, Navigation, Timing

A hub of operator-usable methods that a soldier with a phone, a compass, and a watch can use to derive heading or position when GPS is unavailable. Every method on this page labels what it gives you, what accuracy to expect, what it requires, and runs entirely in your browser — no backend, no telemetry, no external calls. This is decision support: the operator confirms before any fires-related action.

Seven Methods · Operator-Usable, Offline, No Special Hardware

METHOD 1

Sun Azimuth (NOAA SPA)

What it gives you True azimuth and elevation of the sun at your location and time.
Accuracy ±0.01° from algorithm; field accuracy ±1° once you put a compass on it.
What it requires Your approximate lat/lon, the local date/time, and a visible sun.
Awaiting input — set lat/lon/date/time and press Compute.
Operator instruction. Point your lensatic compass at the sun. Read the magnetic bearing. Subtract magnetic declination from method 7 to get true heading. Compare to the azimuth above; the difference confirms or corrects your compass.
Decision support. Operator confirms before any fires-related action.
METHOD 2

Shadow-Stick Method

What it gives you True east–west line, and from that, true north.
Accuracy ±2°, depending on stick verticality and shadow definition.
What it requires A stick (≥30 cm), 15–30 minutes, visible sun, no overcast.
ground stick T1 (West) T2 (East) E – W line N
  1. Plant a vertical stick (≥30 cm). Verticality matters — eyeball or string-and-rock plumb.
  2. Mark the tip of its shadow on the ground. Call this T1.
  3. Wait 15–30 minutes. Mark the new shadow tip T2.
  4. The line from T1 → T2 runs west to east in the Northern Hemisphere (T1 is west, T2 is east). South of the equator, T1 is east and T2 is west — flip it.
  5. Stand with the sun on your back, perpendicular to the T1–T2 line. You are facing north (south, in Southern Hemisphere).
Operator instruction. Cross-check the heading with your lensatic compass + the declination from method 7. Two independent methods agreeing = confidence. Disagreement = pick a third method before you commit a movement order.
Works any latitude. Requires visible sun and no overcast. ±2° depending on stick verticality and shadow definition. Takes 15–30 min. Decision support.
METHOD 3

Polaris Fix (Northern Hemisphere)

What it gives you True north, plus a free latitude check.
Accuracy ±1° for hand-held use; the 0.7° pole-offset is included as a small constant.
What it requires Clear night sky, latitude greater than ~5° N (Polaris below horizon at the equator).
Polaris's elevation above the horizon equals your latitude. Enter your approximate latitude and press the button to see the expected horizon angle for Polaris tonight.
  1. Find the Big Dipper (Ursa Major). Locate the two "pointer stars" at the end of the bowl — Dubhe (top) and Merak (bottom).
  2. Extend the pointer line upward (out of the bowl) about 5× the distance between the pointers. You arrive at Polaris.
  3. Polaris's elevation above the horizon equals your latitude. If they don't match within ±1°, you have the wrong star (often Kochab) — verify the Big Dipper extension.
  4. Polaris currently sits ~0.7° from true celestial north (epoch 2026; drifts slowly over decades). Drop a vertical from Polaris straight down to the horizon — that point is true north, accurate to ±1° for hand-held use.
Operator instruction. Take a back-azimuth from true north, cross-reference with method 7 (declination) for your magnetic compass, and confirm with Method 1 at sunrise. Three independent fixes = navigation confidence.
Requires clear night. Latitude > ~5° N (Polaris below horizon at equator). The 0.7° offset is approximate for the 2026 epoch and drifts over decades.
METHOD 4

Southern Cross Fix (Southern Hemisphere)

What it gives you True south.
Accuracy ±1.5° for hand-held use.
What it requires Clear night sky, southern latitudes (typically below ~25° N).
Enter your latitude. Crux is fully visible at all southern latitudes and as far north as ~25° N (briefly, low on horizon).
  1. Find the Southern Cross (Crux) — four bright stars in a kite shape. Do not confuse with the False Cross (Vela/Carina), which is larger, dimmer, and lacks a fifth star (Epsilon Crucis) inside the kite.
  2. Find the two pointer stars Alpha and Beta Centauri nearby — the brightest pair pointing toward Crux.
  3. Extend the long axis of the Cross 4.5× its length toward the foot.
  4. From the midpoint between Alpha and Beta Centauri, draw a perpendicular line. The intersection with the extended Crux axis approximates the south celestial pole.
  5. Drop a vertical from that point to the horizon — true south, accurate to ±1.5° for hand-held use.
Operator instruction. Add 180° to the south-bearing to derive a true-north reference; cross-check with method 7 for magnetic compass correction. The False Cross is the most common error source — verify Epsilon Crucis is inside the kite.
Requires clear night, southern latitudes (typically below ~25° N). The False Cross is a common error source.
METHOD 5

Two-Landmark Resection

What it gives you Your own lat/lon from bearings to two known landmarks, plus a ±1°-bearing-error uncertainty radius.
Accuracy ~10–200 m typical for landmarks 1–10 km away with ±1° bearing precision.
What it requires Two visible landmarks of known coordinates and accurate true-bearings (compass + declination from method 7).
Awaiting input — fill landmark coords + bearings and press Compute.
Operator instruction. The estimated radius assumes ±1° bearing error. If your compass is older / un-calibrated / near steel, double it. Use a third landmark when uncertainty matters; the inverse problem (project a target from a known anchor) is on /field.
Flat-earth approximation valid for distances under ~20 km. Bearings within 5° of parallel will be rejected.
METHOD 6

Dead Reckoning · Pace Count

What it gives you Cumulative projected position from a starting point and a series of (heading, distance) legs.
Accuracy Drift bound shown in two columns: foot-mobile (~5%/dist) and wheeled (~2%/dist).
What it requires A known start point, a compass with declination applied, a pace count (or odometer).
Add a segment to start tracking.
Operator instruction. Re-anchor whenever you can — visible landmark (method 5), sun (methods 1–2), Polaris (method 3) — drift is monotonic and only resets on a fix.
Drift estimates are illustrative. Real drift depends on terrain, fatigue, terrain compensation discipline, IMU grade, vehicle dynamics, and aiding sources.
METHOD 7

Magnetic Declination Lookup

What it gives you Approximate magnetic declination (deg E or W) at your lat/lon for the 2025–2030 epoch.
Accuracy ±2–3° (sanity-check grade). USE YOUR MAP'S MARGINAL DATA for precision navigation.
What it requires Lat / lon and the operation date.
Enter lat/lon and press Lookup.
Honesty footer. This is a coarse interpolation accurate to ±2–3° for use as a sanity check. For precision navigation, USE THE DECLINATION PRINTED IN YOUR MAP'S MARGINAL DATA — it is the authoritative value for your AO and operation date.
Built from a ~22-point worldwide grid for the 2026 epoch. Polar regions (lat >|85°|) flagged as unstable; use celestial.

Cross-Link · Existing Surfaces That Pair With This Toolkit

/fieldAnchor + bearing + range PROJECTION (the inverse of resection — known anchor, derive target). When you have a known surveyed point and need to project a target's coordinates from a measured bearing and range — use field. Counterpart to method 5 above (resection). /phonePhoto intake; EXIF GPS auto-extract when present; falls back to anchor + bearing + range or map tap. Use this when the soldier in the field is the sensor and the EOC needs the cue on the COP. /gps-deniedJammer awareness + uncertainty growth simulator (R-330Zh, Pole-21, Iranian, DPRK profiles). See how your position uncertainty cone grows under specific adversary jammer profiles — useful for SIGINT/EW awareness training. Methods 1–7 above let you re-anchor when uncertainty grows past acceptable bounds.

Hard Rules · Honest Disclosures

What this page is, and what it is not

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