PrimeBite Fishing Solunar Windows (Baseline) Full Transparency

Solunar Windows (Baseline) — Full Transparency

Last updated: 2026-02-04

This page documents the Solunar Windows (Baseline) profile: classic solunar timing only (Major/Minor windows, dawn/dusk overlap, moon phase curve). Best for freshwater when your species isn't listed (e.g. bass, crappie, bluegill). It is not species-verified.

Below: exact equations, every variable, open-access URLs, verbatim quotes (with page pointers), and what is research-backed vs calibrated.

On this page

The exact math (Solunar Windows Baseline)

Baseline is a Major + Minor window rating: each solunar window gets a 1.0–5.0 score via evidence-backed window-scale calibration, and the day score is the duration-weighted average of all window scores. 

// Per-window lift (Baseline)
L_total = L_base + L_phase + L_overlap

// Window-scale calibration (scale choice; evidence-backed floor/ceiling logic)
// Major: L_total [0.082, 0.122] → rating [2.0, 5.0] (floor 2.0 — Shaw 2021: Major always a lift)
// Minor: Piecewise — [0.022, 0.026] → [1.0, 1.3], [0.026, 0.09] → [1.3, 3.0]
rating = mapBaselineLiftToRating(L_total, windowType)

// Calibrated trust rule (Major-only display gate):
// In the quarter band (near 1st/3rd quarter), Major ratings are capped at ≤ 4.2 (after display rounding).

// Day rating
day_rating = duration-weighted average of all window ratings

Research-backed: L_base Major = 0.10 (Shaw 2021: ~10–12% success lift when moon overhead/underfoot). Calibrated: L_base Minor, L_phase magnitudes (±0.018), L_overlap max (0.04), and the exact mapping ranges.

Key design choice: Moon phase (±0.018) is the dominant driver; twilight overlap (max 0.04) is secondary.

Calculation methodology

Step-by-step reference for Solunar Windows (Baseline).

Step 1) Base lift (per window type)
L_base = 0.10 for Major (moon overhead/underfoot) — research-backed (Shaw 2021)
L_base = 0.04 for Minor (moonrise/moonset) — calibrated (conservative)

Step 2) Moon phase lift (smooth curve; evidence-direction)
Use moon phase position (0=new, 0.25/0.75=quarters, 0.5=full):
- Quarter phases are lowest (down to −0.018)
- Gibbous phases are higher (up to +0.018; peaks around waxing/waning gibbous)
- Smooth curve transitions between; no hard steps

Step 3) Dawn/dusk overlap lift
overlap_fraction = fraction of window inside civil twilight (sun 0° to −6°)
L_overlap = 0.04 × overlap_fraction   // 0..0.04 (calibrated; direction from Shaw)

Step 4) Total lift
L_total = L_base + L_phase + L_overlap

Step 5) Window-scale calibration (scale choice)
Major: rating = 2.0 + 3.0 × (L_total - 0.082) / (0.122 - 0.082)  → [2.0, 5.0]
Minor: piecewise —
  if L_total < 0.026: rating = 1.0 + 0.3 × (L_total - 0.022) / (0.026 - 0.022)  → [1.0, 1.3]
  else: rating = 1.3 + 1.7 × (L_total - 0.026) / (0.09 - 0.026)  → [1.3, 3.0]

Step 5b) Calibrated trust rule (Major-only)
If moon phase is in the quarter band (near 1st/3rd quarter), Major window ratings are capped at ≤ 4.2 (after display rounding).

Step 6) Day rating
day_rating = duration-weighted average of all window ratings

Window-scale calibration (why Major floor 2.0, Minor ceiling 3.0)

Major floor = 2.0: Shaw et al. 2021 found that anglers were ~10–12% more likely to be successful when the moon was overhead or underfoot rather than when neither lunar event occurred. So being in a Major window is always a lift vs no event; we do not map worst Major to 1.0.

Minor ceiling = 3.0: We have no open-access PDF that compares Major vs Minor effect size. By caution we cap Minor ratings at 3.0 so we do not present Minor windows as equivalent to the best Major conditions.

Rarity targets (calibrated): 1.0 Minor ~2.7% of days (~once every 36.5 days); 5.0 Major ~1.8% of days (~once every 56 days).

Variables (what's research-backed vs calibrated)

Research-backed = driver/pattern supported by open-access source with quote. Calibrated = we chose the exact value/cap for a stable 1–5 score; direction may still match literature.

Moon position — Major (L_base = 0.10)

Research-backed: ~10–12% higher success when moon overhead/underfoot.

Source (open access): Shaw et al. 2021 — PLOS ONE

"Anglers were observed to be about 10–12% more likely to be successful when the moon was overhead or underfoot during their trip rather than when neither lunar event occurred during an angling event (Fig 2D)."

(PDF p.13)

Moon position — Minor (L_base = 0.04)

Calibrated: Moonrise/moonset has less direct evidence than overhead/underfoot; 0.04 is conservative relative to 0.10.

Moon phase (L_phase ±0.018)

Calibrated (direction from Shaw): Gibbous highest, quarter lowest in source; we use a smooth phase curve (±0.018) so moon phase is the dominant driver over twilight overlap.

Source (open access): Shaw et al. 2021 — PDF (printable)

"The odds of a successful trip were highest during the gibbous phases… and lowest during the quarter phases…"

(PDF p.13)

Dawn/dusk overlap (L_overlap max 0.04)

Calibrated (direction from Shaw): Lower solar intensity → higher success; we use civil twilight overlap as proxy. Magnitude 0.04 is calibrated to keep twilight secondary to phase.

Source (open access): Shaw et al. 2021 — PDF (printable)

"Mean daily solar radiation had a negative effect on walleye trip success… The observed percent of successful trips tended to increase with decreasing solar intensity …"

(PDF p.11)

Window-scale calibration

Evidence-backed + calibrated: Major floor from Shaw 2021 (Major always a lift vs no event). Minor ceiling by caution (no evidence Minor = best). Scale endpoints calibrated to achieve rarity targets.

Current values:

Major quarter cap (≤ 4.2 in quarter band)

Calibrated (trust rule; not a biological claim): If moon phase is in the quarter band (near 1st/3rd quarter), Major window ratings are capped at ≤ 4.2 (after display rounding). This prevents quarter-phase windows from being “near-perfect” due to overlap alone.

Key definitions & verification sources

Civil twilight (overlap window)

Used for: Defining when a solunar window "overlaps" dawn/dusk (overlap_fraction).

Source (open access): NWS/NOAA — Twilight definitions

"Morning civil twilight begins when the geometric center of the sun is 6 degrees below the horizon, and ends at sunrise. Evening civil twilight begins at sunset, and ends when the geometric center of the sun is 6 degrees below the horizon."

Worked example (inputs → lift → rating)

Example: Major window, no overlap, neutral phase.

Example: Major window, strongest conditions (gibbous peak + strong twilight overlap).

Model changelog (Solunar Windows Baseline)

Canonical doc source

Canonical content lives in the app repository docs (mirrored here for public transparency):

PrimeBite Fishing — Transparency pages are living documents. If you spot an error, please report it.