# The Celestial Theodolite
A method of measuring the precise timing of celestial occlusions, which are moments when a celestial object intersects with a terrestrial reference point. By recording when and where these intersections occur, we can compare the observed timing against predictions made by two competing geometric models. Whichever horizontal reference is correct, whether a plane or a sphere, the geometric alignment at the time of occlusion can distinguish between them.
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## I. Foundations
Start here. These pages establish the historical and conceptual groundwork that the entire method is built on.
**[[00_Introduction]]**
Where it all begins. Traces the two-sphere model (celestial sphere + terrestrial sphere) from Ptolemy through modern celestial navigation. Establishes that apparent star positions keep the system internally consistent, and introduces the key insight: using the star's true position instead of its apparent position creates an external test of the system. Covers the link between archaeoastronomy and the Cel Theo method.
**[[03_Celestial_Sphere_Equivalences]]**
Shows the mathematical equivalence between using a physical elevation of 6,371 km and a sphere with a radius of 6,371 km. Explains why the radius of vision and the radius of Earth produce the same angular relationships, which is what makes the celestial sphere model work on both a plane and a globe.
**[[04_Principles_of_Occlusions]]**
Covers the optics behind what we're actually measuring. Real images vs virtual images, how shadows form, Snell's law as it relates to the bending of light, and the boundary conditions that matter when a star is being occluded by a terrestrial feature.
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## II. The Method
How the test actually works. Read these in order.
**[[01_Cel_Theo_Process]]**
Step by step process and methodology for building a celestial theodolite measurement. How to gather coordinates, distances, elevations, and how to use Stellarium + Google Earth + the spreadsheet to generate predictions.
**[[02_Null_Hypothesis]]**
Sets up the formal hypothesis test. H0: Earth is a globe. H1: Earth is not a globe. Defines the independent variables (observer distance and elevation), the control (known peak elevation), and the dependent variable (occlusion time/angle). Covers the Fisher and Neyman-Pearson frameworks and Popper's falsifiability criterion.
**[[Why_the_Globe_Predicts_an_Earlier_Time]]**
The core geometric explanation of why the two models produce different predictions. On a globe, the central angle between observer and peak creates a drop that lowers the predicted star intersection angle, meaning the globe expects the occlusion to happen earlier. Walks through the Pikes Peak data cell by cell.
**[[Cel_Theo_And_Central_Angle]]**
Breaks down the central angle theorem as it applies to Cel Theo. Shows the full central angle (gamma), the half central angle (gamma/2), and how the flat earth prediction requires the star to traverse the entire angular separation while the globe prediction subtracts the curvature drop.
**[[FE_and_the_Central_Angle]]**
Round Table 121 summary. Ties together the three Euclid theorems with the cel theo analysis in plain terms. Covers why the globe predicts earlier, what happens when the arc length is added back, why refraction geometrically recovers the flat baseline, the emergence reversal, and the null hypothesis implications.
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## III. Refraction
The atmosphere bends light. This section examines whether refraction can account for the discrepancy between globe predictions and observations.
**[[093_Celestial_Refraction]]**
Comprehensive overview of refraction: Snell's law, terrestrial vs astronomical refraction, the empirical formulas used, and why the two types are mechanistically different. Covers the boundary layer, Laplace's theorem, and the assumptions baked into standard refraction corrections. Note: Contains outdated info graphs. Physics summary of astro refraction still holds.
**[[Refraction_and_Half_Gamma]]**
Compares measured astronomical refraction against the half central angle (gamma/2) for each observation. If refraction consistently matches gamma/2, it's doing the work of compensating for curvature rather than describing an independent atmospheric phenomenon. Includes ratio analysis across all peaks.
**[[Refraction_and_Gamma]]**
Same analysis but against the full central angle (gamma). Tests whether refraction exceeds the total arc between observer and peak. Companion piece to the half-gamma page.
**[[Emergence_vs_Occlusion]]**
The directional test that breaks refraction as a rescue. 11 occlusions and 7 emergences produce contradictory refraction requirements depending on whether the star is appearing or disappearing. If refraction were a real atmospheric correction, it couldn't flip behavior based on direction. Demonstrates that the true position produces a clean geometric result while refraction introduces noise with no pattern.
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## IV. Data and Analysis
The measurements, the graphs, and the statistical analysis backing it all up.
**[[86_Peak_Star_Analysis]]**
32 observations across 14 peaks. Each entry compares the FE and GE predicted peak elevation angles against the star's true geocentric position at the time of occlusion. Includes per-peak plots and residual tables.
**[[85_Inscribed_Angle_Residual]]**
Decomposes each observation's GE residual into its two algebraic components: the FE residual plus the curvature drop (theta_drop). Proves this is an identity, not an approximation. The GE residual is always the FE residual plus the full drop correction across all 29 included observations.
**[[87_Intersection_Analysis]]**
Visual walkthrough of specific star-peak intersections using Stellarium screenshots. Shows the true position intersection before emergence, the timing gaps, and how the half central angle shows up in the elevation error.
**[[88_Planar_Math_vs_Globe]]**
Desmos graph and PDF showing the geometric comparison of planar trigonometry vs globe trigonometry for peak elevation calculations.
**[[Central_Angle_Test]]**
Tests how refraction changes the central angle upon intersection relative to the arc length of the ground. Uses Pikes Peak / 39 Aquarii and Blodgett Peak / LP Aquarii as examples with apparent vs geocentric position comparisons.
**[[89_RSS_Error_Analysis_Guide]]**
Full documentation of the Root Sum Square error propagation methodology. Covers partial derivatives, how each source of measurement uncertainty (elevation, distance, timing) feeds into the final distance and angle predictions for both models.
**[[90_Error_Bars]]**
The graphs. Distance and elevation error bar plots for each peak (Pikes Peak, Blodgett, Blue Mtn, Cheyenne, Ediz-Blyn, Getaway, Green Mtn, Hounds Tooth, Mount Rosa, North Peak, Old Blyn, Varley SE2 Squamish). Generated from the RSS analysis.
**[[Distances_on_FE]]**
Notes on using the Haversine formula for computing distances between observer and peak coordinates on the celestial/terrestrial sphere.
### Data Processing Logs
Session-by-session records of data reduction work.
- [[Data_Processing/2025-12-31]]
- [[Data_Processing/2026_1_24]]
- [[Data_Processing/2026_1_25-26]]
- [[Data_Processing/2026-2-5]]
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## V. Extended Applications
**[[92_Eclipses]]**
The same Cel Theo technique applied to solar eclipses. Includes the 2024 and Oct 2023 eclipse data. The 2023 analysis yielded an average sun height of 6,367,512 m with a standard deviation of 7,506 m across 4,550 data points.
**[[91_Celestial_Bounty]]**
The Celestial Theodolite Measurement Reward Program. Up to $200 per qualifying recording for independent observers. Includes eligibility requirements, equipment specs, and example recordings.
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## VI. Debate and Critique
Responses to objections and the strongest version of the argument.
**[[Steel_Man_Celestial_Theodolite]]**
The strongest possible presentation of the Cel Theo case, compiled from Updates XXVII through XXXVII. Covers the methodology, null hypothesis framework, how predictions are generated, and the core findings in a concise format.
**[[96_FAQ]]**
Responses to common questions and YouTube comments. Covers negative angles, "where is the star" objections, and detailed refutations of refraction-based counterarguments.
**[[Cel_Theo_Questions]]**
Five foundational questions designed to establish agreed-upon premises before a debate. Covers geocentric motion at 60 NMi/degree, topocentric-to-geocentric transformations, geographic position of a star, eclipse predictions, and the observer's local horizon.
### Critiques and Responses
- [[Critiques/Cele_Theo_Spreadsheet_v911_ Critiques]] — Specific critiques of the spreadsheet v9.1.1
- [[Critiques/Roohif_and_Co]] — Response to Roohif et al.
- [[Critiques/Randy-McRanderson]] — Response to Randy McRanderson
- [[Critiques/New-Sheet-Analysis]] — Analysis of the revised spreadsheet
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## VII. Reference
**[[99_Definitions]]**
Glossary of all terms used across the project. Aberration, archaeoastronomy, azimuth, celestial refraction, celestial sphere, terrestrial sphere, occlusion, apparent vs true position, and more.
**[[97_Notation_Index_1]]** and **[[97_Notation_Index_2]]**
Full index of every symbol, variable, and equation used in the spreadsheet and across the Cel Theo pages.
**[[97_Resources]]**
External links: the main spreadsheet, definition glossaries (USNO, NED/IPAC, BAA), and refraction references.
**[[Spreadsheet_Change_Log]]**
Version history and changes to the Cel Theo Calculator spreadsheet.
**[[94_Geometric_vs_Apparent]]**
(Stub) Geometric vs apparent star positions.
**[[95_Occlusion_Results]]**
(Stub) Occlusion results.
**[[98_Starlogs]]**
(Stub) Star observation logs.
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