Our method — chart calculation and interpretation

Natal Blueprint builds every reading from Swiss Ephemeris–class astronomical data. A language model then writes under astrologer-designed rules — grounded in that calculated chart, never in improvised sky. The same fact sheet powers Natal Lite, Natal Heavy, the Compatibility Report, and consultation with Mara Vance. Later chapters and later questions resume that sheet; they do not get a second natal.

This page is Natal Blueprint’s canonical public methodology document: what we calculate, which schools orient the reading, what we refuse to invent, and how we use AI without letting the model become the astronomer. Technique tables continue on the astrology methodology companion.

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Table of Contents

• How to cite this document
• Scope
• How we use AI
• Your chart, not a guess
• Method layers
• Data integrity
• Standing chart, per-question sky
• Place, timezone, and birth-time honesty
• How a report is built
• One stack, two interfaces
• Portrait and operational voice
• Compatibility sittings
• Methods we use
• Whole Sign as a check ledger
• Local parans and the 10-minute clock
• Interpretation policy
• Field, not verdict
• Count honesty
• Two element counts
• Aspect honesty
• Living sky — birth chart plus current and future
• What we never invent / out of scope
• How to verify a provider
• See it in practice

How to cite this document

Title: Our method — chart calculation and interpretation methodology
Publisher: Natal Blueprint
Canonical URL: https://www.natalblueprint.com/our-method
First published: 5 August 2026
Last revised: 16 September 2026

Suggested citation: Natal Blueprint, Our method — chart calculation and interpretation methodology, https://www.natalblueprint.com/our-method, revised 16 September 2026.

Use this URL when comparing providers, briefing editors, or grounding AI Overview–style summaries in a primary source. Named figures below are orienting influences on calculation or synthesis — not celebrity endorsements of any author’s complete system.

Scope

This document covers data integrity, how calculation and language stay separate, the shared report/consultation stack, method layers, the core chart and selective schools, public interpretation policy, living-sky evidence, and explicit non-claims.

Orb tables, school-by-school technique wording, and a plain-language midpoints explainer live on the astrology methodology article. The product catalogue — what we sell, includes/excludes, and calculator comparison — is what we offer.

How we use AI

Natal Blueprint is built so the language model never has to be the astronomer. A sentence model can look at an engine and still corrupt the list. Software owns facts; the model owns prose under written rules; finished claims are checked against the facts. That is ordinary disciplined AI practice, applied to a chart.

• Calculation is software. Positions, houses, aspects, ages, and dated sky come from an astronomical engine. The model does not look up the sky.
• Interpretation is synthesis under written rules. An astrologer-designed policy says what a placement can mean and what it cannot claim — field, not fate; labeled schools; no invented contacts.
• The chart is a single source of truth. One calculated fact sheet is pinned for the report or the sitting. Later chapters and later questions resume it. Today’s transit is added beside it, never instead of it.
• Claims are closed-world. A planet, aspect, age, or between-you contact ships only if it is on that sheet. If the engine did not name it, the reading does not.
• Quality is checked against the chart, not against a longer prompt. Paid reports are audited for placements, counts, aspect types, and ages before delivery. Consultation uses the same chart; a post-check is alert-only so chat is not delayed. When a class of error appears, we fix the calculation layer — we do not paper over it in wording.
• Limits are published. Birth-time honesty, parked techniques, and non-claims live on this page. We would rather name a method we do not use than imply a silent mash-up.

That is the public contract. The internals of how software and models are arranged stay in-house. You can verify the contract from the reading, the wheel, and the sky archive — not from a recipe.

Your chart, not a guess

Here is the shortest way to watch that contract fail or hold — on your sky, in one sitting, with no sales pitch in between.

You sign up, load your blueprint in the consultation, and tick the 10-minute box if you want the bonus star list. You download the natal blueprint PNG and attach that wheel picture in ChatGPT — do not type your birth details there. You give Mara the same list question. Then you find one placement ChatGPT got wrong. If the placements are wrong, the interpretation is on a bad map. Fixed stars are extra: they are not drawn on the wheel.

Natal Blueprint calculated that list. Software owns it. The writer interprets it. That gap is this method, happening in five minutes, not a slogan. Run the ChatGPT natal test — pin the chart and find one wrong placement.

Method layers

Three layers must not be conflated:

• Voice / persona — psychological + evolutionary synthesis with traditional care for planetary condition (sect, essential dignity, reception named as reception, dispositors). Orienting influences: Liz Greene (psychological), Robert Hand (traditional rigour), Jeff Green (evolutionary). Meaning leads; mechanics support. Field, not verdict.
• Structural spine — luminaries, Ascendant, chart ruler and dispositor chain, planetary condition (sect, dignity, angularity), the chart’s central contradiction, and — when a question or focus is supplied — the topic houses first. The spine is the story scaffold.
• Factor schools — how selective data (fixed stars, goddess asteroids, midpoints, declinations, antiscia, lots, planetary lines) is calculated and labeled so the synthesis knows which school it is using. Schools decorate the spine; they do not replace it.

Same methodology on every channel; depth of prose differs. Browser Individual Consultation, Compatibility Consultation, and Telegram Deep receive the same calculated schools. Deep writes denser sitting-level prose. It does not invent a second calculation method.

Data integrity

Engine-backed means every planet, house cusp, aspect type, and fixed-star contact in the reading comes from the calculated chart — not from a language model guessing the sky. Element shares name the Sun-through-Pluto bodies. When Mara answers a dated transit question, she uses a dated transit-to-natal lookup from that same stack. Ages on a transit date are derived from your date of birth. Lord of the Year is the engine year-lord, not a guessed planet. The year’s Moon, a return Moon, or a progressed Moon is not the natal Moon.

Paid reports are checked against that ledger before delivery. A draft that hangs “the one fire planet” on an air Sun, or names Venus conjunct Saturn when the tables show quincunx, does not ship as written. Mara’s post-check on the assembled reply is alert-only so chat is not delayed.

Birth-time honesty matters more than ephemeris polish. A precise engine with a wrong time still misplaces houses and angles. If your time is unknown or left blank, we noon-fill the clock, stamp a time-quality watermark, and treat angular, house, and year-lord claims as provisional rather than overselling certainty.

Standing chart, per-question sky

The calculated fact sheet is not rebuilt from scratch on every writing pass. Reports and Mara pin one natal (or two-chart) ledger for the job. Later report chapters still see the same planets, orbs, and aspect types as the opening. Mara’s seventh question still reads the same chart as her first.

What changes per turn sits beside that ledger: dated transit-to-natal sky, and the kind of answer the question needs. Today’s weather cannot rewrite the natal census. A new question cannot reassign a planet’s house. The standing block belongs only to the native — or to the two people already in a Compatibility sitting. A spouse’s birth details pasted into Individual Consultation are not a second natal.

Place, timezone, and birth-time honesty

Birth place is geocoded to latitude, longitude, and an IANA timezone name (for example Australia/Sydney). Those coordinates and the timezone string go to the chart engine with date and time. House cusps and angles are therefore computed for the actual local instant, not a guessed zone.

If the city string is ambiguous, the order form asks you to pick a candidate. If birth time is blank, we default to noon, stamp a time-quality watermark on the report, and still print the calculated houses so the ledger is complete. Tropical planetary longitudes for the date still stand; rising sign and house overlays do not. Local parans are not fetched on a noon-fill or an unattested clock — see local parans.

How a report is built

The language model writes from a verified fact sheet. It does not invent placements. The public sequence is:

1. Calculate and validate — Swiss Ephemeris–class natal (or two natals for synastry) from date, time, coordinates, and timezone.
2. Identify strongest structures — luminaries, Ascendant, chart ruler, close aspects, central contradiction; for synastry, contacts and overlays between the two charts.
3. Keep figures honest — named aspect types match the calculated pair. Published orbs: 8° for majors involving Sun, Moon, Ascendant, MC, or Descendant; 6° for other majors; 2° for star ecliptic conjunctions. We write exact or within a degree only when that orb is under 1.0°. Mixed-sign degree aspects are named out of sign. A star overlay on a planet is not a planet-to-planet conjunction.
4. Add selective texture — fixed stars, asteroids, midpoints, and related layers only when they earn a place beside the spine. Default stars are ecliptic overlays. When you attest the clock within 10 minutes, Brady natal parans lead and overlays stay labeled texture.
5. Synthesise one narrative — lived meaning, not a keyword dump. Natal Heavy’s Next Chapter names one through-line, then timing windows — not a filing cabinet of techniques.
6. Check the prose against the chart — automated editorial gates, then a chart-backed audit of placements, named census, aspect types, occupied houses, verified stars, ages, and year-lord. A human astrologer does not sign each PDF.
7. Deliver — HTML and PDF, typically within two hours. The PDF attachment is yours to keep. Hosted links last 7 days; sign in with the order email within 7 days to keep the HTML in Your reports. Optional Mara questions reuse the same engine fact sheet.

Product list, includes/excludes, and calculator comparison: what we offer.

One stack, two interfaces

Reports and consultation are not two different astrology products glued together.

• Rich astrological reports — Natal Lite, Natal Heavy, and Compatibility deliver a synthesised narrative from the full enriched chart (and timing layers on Heavy), as HTML for reading online and PDF when you want a download.
• Consultation interface — Natal Blueprint Now in the browser (Individual Consultation or Compatibility Consultation) and Telegram Deep attach the same natal enrichment. You ask questions; dated sky for that turn sits beside the pinned chart. Browser and Deep differ in depth of prose. The calculation method does not.

Astrocartography on Mara is on-ask only. Planetary lines are not standing chart texture. Paid reports do not ship a dedicated Earth chapter by default — that technique is parked, not deleted. Consultation injects lines only when the question asks about place or already turns on a named city.

Portrait and operational voice

This is not a SKU. Identity and synastry portrait chapters read as meaning — who this person is, how the bond feels. Timing chapters and Practical Instructions stay operational — the nature of the time, and how the chart actually works day to day. Mara follows the same split: a meaning question is answered as portrait; a what-should-I-do question is answered as a move. The calculated chart does not change with the beat.

Compatibility sittings

A Compatibility Report and a Compatibility Consultation sitting both hold two calculated charts. Synastry is the technique: contacts and house overlays between those charts. A labeled composite (the midpoint relationship entity) may be cited when the engine returns it. That is a school inside this offering, not a fourth product and not a composite-only PDF.

When you ask how you two actually live together — where it is easy, where it costs — the answer is a map of the contacts the engine found, with both people named. Soft contacts stay on the easy side of that map; hard contacts stay on the work side. We do not invent a pair the ledger does not list, swap one person’s star or planet onto the other, or fill the gap with one natal leftover house.

An Individual Consultation sitting cannot invent the other person’s chart. If the question needs two people, that is Compatibility Consultation — pin both, then ask.

Methods we use

Short account of what is in production. Each named figure is an orienting influence on how we calculate or synthesise — not a claim that we reproduce that author’s complete system.

Core chart — planets, signs, houses

This is how we put the primary fact sheet together before any selective school is woven in:

• Western tropical zodiac — planetary longitudes anchored to the seasons, calculated with Swiss Ephemeris–class data. Standard for Western natal work; not a sidereal / Vedic claim.
• Placidus houses — quadrant house cusps from birth time and place, so planets are read in both sign (character / style) and house (life domain). This is the published house system; there is no customer toggle.
• Planets in signs and houses, plus major aspects — the ten planets Sun through Pluto, the angles, Nodes, and the major aspect web as one interconnected system. Each named pair uses the engine aspect type. Element tallies use those ten bodies only and name them.
• Chart ruler, dispositors, sect, dignity, and reception — who rules the Ascendant, how planets condition each other through rulership, day/night sect, and essential dignity as planetary condition. Being in each other’s signs is reception; we do not call that essential dignity. Orienting influence: Robert Hand.
• Whole-chart psychological + evolutionary synthesis — identity, emotion, relationship, vocation, and growth tension, including the chart’s central contradiction. Orienting influences: Liz Greene, Jeff Green.

Whole Sign as a check ledger

Whole Sign occupancy is computed from the Ascendant sign and each planet’s sign. It is not the published house system and does not overwrite Placidus house numbers. When a Sun-through-Pluto body (or MC / IC) sits in a different Whole Sign house than its Placidus house, the reading may name that split as a labeled check. If there are no splits, Whole Sign stays out of the prose. No customer house-system toggle.

Selective techniques below decorate this spine. They do not replace planets, signs, houses, or the chart-ruler chain.

Selective schools — texture on the spine

• Fixed stars — Diana K. Rosenberg (longitude overlay) by default — ecliptic-longitude conjunctions of catalogue stars to natal planets or angles. First use in prose names the contact as a zodiacal overlay: doctrine is a rhyme the life may echo, not a governor welded to the planet, and not the living sky at the birth place. Polaris, if listed, is projected ecliptic longitude, not the pole overhead. We say exact only when the orb is under 1.0°. Stars are a natal technique, not a synastry SKU: we do not sell a Fixed-Star Synastry Report. When the clock is attested, these overlays stay as labeled texture beside Brady parans — see local parans.
• Goddess asteroids — Demetra George — Ceres, Pallas, Juno, and Vesta as archetypal voices. Juno is not a replacement for Venus; Ceres is not a second Moon. Foreground only when they add insight the overlapping personal planet does not already carry. Chiron and Mean Black Moon Lilith sit alongside as modern counseling bodies.
• Key midpoints — Reinhold Ebertin (cosmobiology) — a focused set of synthesis pairs (for example Sun/Moon, Venus/Mars, Asc/MC), woven where they clarify the core story. Midpoints support the reading; they do not open it. Not a full COSI encyclopaedia and not a Lang–Wescott / Uranian dial tree.
• Declinations, antiscia, and lots — traditional + modern texture — parallels / out-of-bounds and antiscia as emphasis when the engine returns them; Fortune, Spirit, and focus-linked lots in the Hellenistic / medieval lots tradition. Used to reinforce themes already live in the luminaries, angles, and major aspects.
• Planetary lines — Jim Lewis / Astro*Carto*Graphy — AC, MC, DC, and IC lines for natal planets, plus power-zone crossings where two lines meet. Lines colour places; they do not prescribe a move. Lewis latitude crossings are not Brady fixed-star parans. Not a checkout SKU. Dedicated Earth chapter parked in paid reports by default; Mara on-ask.
• Composite — Compatibility school — the midpoint relationship entity (Ascendant / Sun / Moon summary) when the engine returns it, inside the Compatibility Report and Compatibility Consultation. Not a fourth SKU.

Local parans and the 10-minute clock

A paran (Bernadette Brady’s diurnal method) is a star and a natal planet simultaneously angular at the birth place — co-rising, co-culminating, co-setting, or on the IC — not a shared ecliptic longitude. That is a stronger stellar contact than a zodiacal overlay when the birth clock is tight enough. A 10-minute error moves the angles enough that a paran can appear or vanish. We never infer clock quality from the time field alone.

Natal Blueprint therefore uses two star schools, gated by an explicit attest:

• Default — Rosenberg ecliptic overlays. Tight longitude conjunctions, written as overlay: a rhyme the life may echo, not the living sky, not a paran, not a governor. This is the honest school when time is blank, noon-filled, uncertain, or unattested — including the free chart and every old order that never asked.
• Attested — Brady natal parans. If you tick that this time is from a certificate or hospital record and accurate within 10 minutes (or answer yes on Telegram /chart), and you actually entered a time, parans become the primary star school. Overlays remain in inventory as zodiacal texture, labeled as overlays, never as parans.

Noon-fill is not good enough. A blank time that we store as 12:00 is not a documented clock. Skipping the question defaults to no. Once you attest on a paid order form or a Mara consultation, we remember that flag on your member account (not extra birth PII) and prefill later sittings and orders. Compatibility person two’s attest stays on that order only.

We do not claim Jim Lewis / Astro*Carto*Graphy paran maps (place maps of star angularity). Those stay out. Natal local parans are a birth-sky technique, not a relocation product.

For orb wording and midpoints in plain terms, see astrology methodology.

Interpretation policy

Selective factors keep a full engine inventory — we do not silent-drop real contacts. Before a non-core factor becomes central story, we ask whether it helps the native understand their life in a way the spine does not already cover. If not, it stays inventory or light texture.

• Core — luminaries, angles, chart ruler, major aspects, central contradiction: always eligible for full interpretation.
• Selective — fixed stars, goddess asteroids, midpoints, declinations, antiscia, lots, planetary lines: foreground only when they earn unique meaning.
• Midpoints — support and clarify; they do not lead the reading.
• Meaning-to-mechanics — prose leads with lived meaning; technical scaffolding supports. Language preference on the order form (Clear, Balanced, more technical) changes how much warrant stays visible — not the calculated chart.
• Timing placement — profections, progressions, solar return, eclipses, and upcoming transit texture belong in Natal Heavy’s Next Chapter or in dated consultation sky — not as a substitute for the natal spine in the main body.

Field, not verdict

The chart is a field of cost and availability, not a legislator. We prefer tends, expensive, available, and also on the list. We do not write that the sky is not offering a life, or appoint “the operation this season.” Both directions of a lifetime trade-off have been done well and badly; which side is funded this season stays choosable.

Natal Heavy’s Next Chapter opens that field once, then applies it. Timing windows name the nature of the time, more than one expression that share that tone, and a question left unanswered. A transit is not narrated as a scheduled event. Behaviour circuits name the operating moves in the chart, including when the old move is still the right tool.

Count honesty

Element balance and planet counts use Sun through Pluto only (ten bodies) and name those bodies — Fire is whoever is actually in a fire sign, not “the Sun” by default. Angles, nodes, Chiron, asteroids, and Arabic parts do not join the percentage. If water is empty, we do not call Pluto — or any air, fire, or earth body — a water planet. A thin-fire chart with Neptune in Sagittarius keeps fire on Neptune, not on an Aquarius Sun.

Reception is named as reception. Saturn in Gemini received by Mercury is not “real dignity.” In a night chart (Sun below the horizon, including pre-dawn) Mars is in sect and Saturn is out of sect; Venus is the sect benefic. Mixed-sign squares are named out of sign.

Two element counts — both valid

A natal wheel from the chart engine often prints its own element bars. The report census for the same chart may read a different percentage. Neither number is a lie. They are different recipes:

• Report census (Sun–Pluto headcount). Ten named planets, one vote each, then a percentage. That is the count the prose, the appendix, and Mara must match. Angles, nodes, and Chiron stay outside the percentage.
• Engine wheel (weighted mix). The render library weights luminaries and angles more heavily and can fold in extra points. The sky positions are the same; the share recipe is not.

We no longer stamp a second gold census over the wheel. The blueprint sits on the page in full, including the engine’s left-hand bars. When you compare the two percentages, read this section — not a painted-over graphic.

Aspect honesty

Every named natal (or synastry) contact uses the engine aspect type for that pair. Venus conjunct the Ascendant can be a conjunction while Venus–Saturn in the same chart is a quincunx. A fixed-star overlay on Saturn is not a Venus–Saturn conjunction. We do not write within a degree or exact unless the engine orb is under 1.0°. Consultation uses the same ledger.

Living sky — birth chart plus current and future

We do not stop at the birth moment. Reports and the consultation interface also calculate current and future sky against your natal chart from the same engine.

• Reports — Natal Heavy includes timing layers (progressions, profections, solar return, eclipses, upcoming transit texture) written as windows on one through-line, then behaviour circuits. Lord of the Year is the engine year-lord. The return Moon, the year’s Moon, and progressed luminaries are not the natal Moon or natal Sun–Moon pair.
• Consultation — each Mara ask can sight dated transit-to-natal sky for the date your question needs. This is how we deliver rich transit and “what’s ahead” guidance in place of standalone transit or daily PDF order forms.
• Account portal evidence — successful consultation sky sightings are archived. Open Sky sightings in your member account to list them and email the full engine snapshot Mara used for that question.

What we never invent / out of scope

• No improvised planetary positions, house cusps, aspect types, or ages.
• No planet assigned to the wrong element (the Sun is not a fire planet unless the Sun–Pluto census lists the Sun under Fire).
• No star overlay counted as a planet-to-planet aspect, treated as a living pole, a paran we did not calculate, or “the tightest contact in your chart.”
• No invented cities, countries, or relocation destinations — planetary lines come from the engine or they are omitted.
• No silent mash-up that treats longitude fixed stars as Brady parans when the clock was not attested, Lewis planetary line crossings as Brady parans, or key midpoints as a full Uranian dial tree.
• No invented planet counts, dignity claimed for reception, or “exact” for aspects wider than 1.0°.
• No legislator pull quote or appointed operation (“the operation this season is”, “the correct move is”).
• No Sabian degree imagery in paid PDF reports — never; consultation may use Sabians only when the engine injects them for that ask.
• No second calculation method for chat versus reports — only depth of prose differs.
• No second natal ledger for a later Mara question or later report chapter — dated sky sits beside the standing chart.
• No invented between-you contacts, and no swapping one person’s placement onto the other, on a Compatibility sitting.
• No claim that we reproduce Greene, Hand, Jeff Green, Rosenberg, Brady, George, Ebertin, or Lewis as complete copied systems.

How to verify a provider

When you compare astrology apps and report services, ask for a methodology page that names calculation, not only marketing adjectives — and that does not confuse a recipe dump with a contract:

• Does it name the ephemeris class and admit birth-time limits?
• Does it name which bodies join an element tally, and quote those names rather than hanging fire on the Sun by default?
• Do named aspect types match an engine list, or can Venus–Saturn become “conjunct” while the tables show quincunx?
• Does it say exact or within a degree only under 1.0°, or inflate a 2.2° contact?
• Does it label selective techniques and say what it does not claim — including overlay stars versus parans, and whether parans require an attested clock?
• Do reports and consultation share one fact sheet, or invent a second sky for chat?
• Do later chapters and later questions resume that fact sheet, or can a new prompt rewrite the natal ledger?
• On a two-person sitting, are both charts calculated, or is the partner guessed?
• Can you inspect living-sky evidence (for us: member sky archives)?
• Is the language model described as the astronomer, or as a writer grounded in calculated facts?

This page is Natal Blueprint’s answer to that test. Technique detail: astrology methodology. Buying checklist context: best astrology reports for 2026. Samples: sample reports.

See it in practice

• What we offer — complete catalogue, includes/excludes, names, and calculator comparison.
• Natal Basic (free) — Swiss Ephemeris wheel and starter aspects.
• Natal Lite / Natal Heavy — rich astrological reports from the same engine.
• Ask Mara — Individual Consultation or Compatibility Consultation on your chart.
• Member account — Sky sightings — archived consultation sky evidence.
• Astrology methodology — technique companion (orbs, schools, midpoints).
• vs traditional reports & human astrologers — category comparison.
• vs Co-Star, The Pattern & ChatGPT — named consumer-app comparison.
• The natal test — pin your chart, attach the natal blueprint PNG in ChatGPT, ask Mara the same list, and find one wrong placement.
• Sample reports — illustrative Jobs / Jackson demos (sample only).