---
title: "Compare calculation conventions or trusted signed releases"
method: POST
path: "/api/astro/convention-compare"
tags: ["Calculations"]
---

# Compare calculation conventions or trusted signed releases

`POST /api/astro/convention-compare`

## Request

- Base URL: `https://api.cosmicephemeris.com`
- URL: `https://api.cosmicephemeris.com/api/astro/convention-compare`
- Auth: one of:
  - HTTP bearer
  - API key in header `x-api-key`

Calculates the same birth under two explicit convention profiles, or verifies and compares two Cosmic Ephemeris-signed responses bound to the same route and canonical input. Release mode works for receipt-enabled releases and does not pretend to recalculate pre-receipt releases. It returns at most 500 field differences and never ranks conventions or provides interpretation. One standard quota unit per admitted request; failed or timed-out admitted attempts are not refunded. Do not automatically retry.
Historical mode uses an explicit BCE/CE date object and UT1 conventions. Its response is the versioned historical envelope, not the modern UTC envelope. Read result for calculation fields and metadata for limits and uncertainty.

## Headers

- `X-Cosmic-Ephemeris-Receipt` 'v1'

## Request body

- union
  - union
    - ConventionProfileCompareRequest
      - `birth` CalculationBirthInput, required: Strict nested birth input; no unknown properties, nulls, booleans or numeric strings. Known civil time required; semantic date/DST/undefined-angle validation occurs on the server.
        - `date` string, date, required: Valid Gregorian YYYY-MM-DD local civil date, inclusive 1800-01-01 through 2200-12-31. Calendar validity and timezone conversion are checked by the server.
        - `time` string, required: HH:MM or HH:MM:SS; no offset in this field. Use timezone to select the civil-time zone.
        - `timezone` string: Valid IANA zone; UTC when omitted. Ambiguous and nonexistent civil times are rejected.
        - `lat` number, required
        - `lon` number, required
      - `profiles` ConventionProfile[], required
        - `zodiac` 'tropical' | 'sidereal', required
        - `ayanamsa` 'lahiri' | 'raman' | 'krishnamurti' | 'fagan_bradley' | 'yukteshwar' | 'sassanian' | 'true_chitra' | 'true_revati' | 'true_pushya' | 'galactic_center_0_sagittarius' | 'galactic_alignment_mardyks'
        - `house_system` 'equal' | 'whole_sign' | 'placidus', required
    - ReleaseCompareRequest
      - `releases` SignedCalculationResponse[], required
        - `receipt` CalculationReceipt, required
          - `schema` 'cosmicephemeris-calculation-receipt-v1', required
          - `kid` string, required
          - `algorithm` 'Ed25519', required
          - `canonicalization` 'cosmicephemeris-canonical-data-v1', required
          - `input_normalization` 'public-request-canonical-data-v1', required
          - `route` string, required
          - `release` string, required
          - `issued_at` string, date-time, required
          - `normalized_input_sha256` string, required
          - `result_sha256` string, required
          - `calculation_profile` object, required
          - `service_dataset_versions` object, required
          - `calculation_fingerprint` string, required
          - `verification_uri` string, required
          - `signature` string, required
  - union: Explicit historical mode, 1000 BCE (BC)–2500 CE (AD). No year zero, implicit calendar, UTC or IANA zone. Preserve tool-specific mathematical, geographic and search limits; calendar/time conventions and estimated Delta-T are not certified historical accuracy.
    - object
      - `birth` object, required: Strict nested birth input; no unknown properties, nulls, booleans or numeric strings. Known civil time required; semantic date/DST/undefined-angle validation occurs on the server.
        - `date` HistoricalDate, required: Explicit civil date, 1000 BCE (BC)–2500 CE (AD); no year zero. Calendar validity is checked by the server. Available only on documented connected historical operations, with explicit UT1/fixed-offset conventions.
          - `year` integer, required
          - `era` 'BCE' | 'CE', required: Display BCE (BC) / CE (AD); API values remain BCE / CE. No year zero.
          - `month` integer, required
          - `day` integer, required
          - `calendar` 'proleptic_gregorian' | 'proleptic_julian', required: Explicit choice; applies the selected calendar rules throughout history without a regional adoption switch.
        - `time` string, required: HH:MM or HH:MM:SS; no offset in this field. Use timezone to select the civil-time zone.
        - `timezone` string, required: Explicit UT1 or fixed offset UT1+/-HH:MM[:SS], within 14 hours. Local clock minus offset yields UT1, not UTC. No IANA timezone inference. Original offset spelling is preserved.
        - `lat` number, required
        - `lon` number, required
      - `profiles` object[], required
        - `zodiac` 'tropical' | 'sidereal', required
        - `ayanamsa` 'lahiri' | 'raman' | 'krishnamurti' | 'fagan_bradley' | 'yukteshwar' | 'sassanian' | 'true_chitra' | 'true_revati' | 'true_pushya' | 'galactic_center_0_sagittarius' | 'galactic_alignment_mardyks'
        - `house_system` 'equal' | 'whole_sign' | 'placidus', required
    - object
      - `releases` object[], required
        - `receipt` object, required
          - `schema` 'cosmicephemeris-calculation-receipt-v1', required
          - `kid` string, required
          - `algorithm` 'Ed25519', required
          - `canonicalization` 'cosmicephemeris-canonical-data-v1', required
          - `input_normalization` 'public-request-canonical-data-v1', required
          - `route` string, required
          - `release` string, required
          - `issued_at` string, date-time, required
          - `normalized_input_sha256` string, required
          - `result_sha256` string, required
          - `calculation_profile` object, required
          - `service_dataset_versions` object, required
          - `calculation_fingerprint` string, required
          - `verification_uri` string, required
          - `signature` string, required

## Response `200`

Convention deltas or verified signed-release field differences

- union
  - ConventionProfileCompareResponse
    - `type` 'convention_compare', required
    - `status` 'current', required
    - `birth` object, required
    - `profiles` object[], required
    - `differences` object, required
    - `metadata` object, required
    - `receipt` CalculationReceipt
      - `schema` 'cosmicephemeris-calculation-receipt-v1', required
      - `kid` string, required
      - `algorithm` 'Ed25519', required
      - `canonicalization` 'cosmicephemeris-canonical-data-v1', required
      - `input_normalization` 'public-request-canonical-data-v1', required
      - `route` string, required
      - `release` string, required
      - `issued_at` string, date-time, required
      - `normalized_input_sha256` string, required
      - `result_sha256` string, required
      - `calculation_profile` object, required
      - `service_dataset_versions` object, required
      - `calculation_fingerprint` string, required
      - `verification_uri` string, required
      - `signature` string, required
  - ReleaseCompareResponse
    - `type` 'release_compare', required
    - `status` 'current', required
    - `route` string, required
    - `normalized_input_sha256` string, required
    - `releases` object[], required
    - `differences` object[], required
      - `path` string, required
      - `left` unknown, required
      - `right` unknown, required
    - `truncated` boolean, required
    - `metadata` object, required
    - `receipt` CalculationReceipt
      - `schema` 'cosmicephemeris-calculation-receipt-v1', required
      - `kid` string, required
      - `algorithm` 'Ed25519', required
      - `canonicalization` 'cosmicephemeris-canonical-data-v1', required
      - `input_normalization` 'public-request-canonical-data-v1', required
      - `route` string, required
      - `release` string, required
      - `issued_at` string, date-time, required
      - `normalized_input_sha256` string, required
      - `result_sha256` string, required
      - `calculation_profile` object, required
      - `service_dataset_versions` object, required
      - `calculation_fingerprint` string, required
      - `verification_uri` string, required
      - `signature` string, required
  - HistoricalConventionCompareConventionCompareResponse
    - `schema` 'cosmicephemeris-historical-calculation-v1', required
    - `status` 'historical', required
    - `type` 'convention-compare', required
    - `input` union, required: Explicit historical mode, 1000 BCE (BC)–2500 CE (AD). No year zero, implicit calendar, UTC or IANA zone. Preserve tool-specific mathematical, geographic and search limits; calendar/time conventions and estimated Delta-T are not certified historical accuracy.
      - object
        - `birth` object, required: Strict nested birth input; no unknown properties, nulls, booleans or numeric strings. Known civil time required; semantic date/DST/undefined-angle validation occurs on the server.
          - `date` HistoricalDate, required: Explicit civil date, 1000 BCE (BC)–2500 CE (AD); no year zero. Calendar validity is checked by the server. Available only on documented connected historical operations, with explicit UT1/fixed-offset conventions.
            - `year` integer, required
            - `era` 'BCE' | 'CE', required: Display BCE (BC) / CE (AD); API values remain BCE / CE. No year zero.
            - `month` integer, required
            - `day` integer, required
            - `calendar` 'proleptic_gregorian' | 'proleptic_julian', required: Explicit choice; applies the selected calendar rules throughout history without a regional adoption switch.
          - `time` string, required: HH:MM or HH:MM:SS; no offset in this field. Use timezone to select the civil-time zone.
          - `timezone` string, required: Explicit UT1 or fixed offset UT1+/-HH:MM[:SS], within 14 hours. Local clock minus offset yields UT1, not UTC. No IANA timezone inference. Original offset spelling is preserved.
          - `lat` number, required
          - `lon` number, required
        - `profiles` object[], required
          - `zodiac` 'tropical' | 'sidereal', required
          - `ayanamsa` 'lahiri' | 'raman' | 'krishnamurti' | 'fagan_bradley' | 'yukteshwar' | 'sassanian' | 'true_chitra' | 'true_revati' | 'true_pushya' | 'galactic_center_0_sagittarius' | 'galactic_alignment_mardyks'
          - `house_system` 'equal' | 'whole_sign' | 'placidus', required
      - object
        - `releases` object[], required
          - `receipt` object, required
            - `schema` 'cosmicephemeris-calculation-receipt-v1', required
            - `kid` string, required
            - `algorithm` 'Ed25519', required
            - `canonicalization` 'cosmicephemeris-canonical-data-v1', required
            - `input_normalization` 'public-request-canonical-data-v1', required
            - `route` string, required
            - `release` string, required
            - `issued_at` string, date-time, required
            - `normalized_input_sha256` string, required
            - `result_sha256` string, required
            - `calculation_profile` object, required
            - `service_dataset_versions` object, required
            - `calculation_fingerprint` string, required
            - `verification_uri` string, required
            - `signature` string, required
    - `result` object, required: Complete historical calculation adapter result. Times are explicit UT1 date records, never UTC strings; derived times may include fractional seconds and years outside the input range.
    - `metadata` object, required
      - `time_standard` 'UT1', required
      - `historical_accuracy_certified` unknown, required
      - `warnings` string[], required

## Other responses

- `400`: Invalid request, malformed JSON, out-of-range date/location, unknown model, invalid timezone or ambiguous/nonexistent clock-change time. Invalid attempts reaching quota reservation consume one unit.
- `401`: Missing, invalid, revoked API key or unavailable activated key owner. Dashboard cookies do not authenticate calculation routes.
- `403`: Origin not allowed by production CORS policy. Server-to-server requests can omit Origin.
- `429`: Monthly quota exhausted, per-user two-request concurrency reached, or nginx rate/connection admission refused. Retry-After: 2 is sent for application per-user concurrency only, not a promise that monthly quota resets in two seconds.
- `502`: Engine unavailable, unsuccessful internal server response or invalid upstream JSON. No engine internals are exposed.
- `503`: Four-request global calculation pool full (Retry-After: 2), maintenance or upstream service unavailable.
- `504`: Application engine timeout: 15 seconds normally; planetary events, house ingresses, aspect windows, event calendar, eclipse geometry, electional search, and event-rule search use 30 seconds; Nakshatra Timeline plus the explicitly enumerated readiness, robustness, location, uncertainty, and electional-audit family use 60 seconds. Timer includes response-body parsing; an admitted timeout consumes quota.

---

[API](https://skmtc.dev/cosmicephemeris/apis/cosmic-ephemeris-calculation-api.md) · [All operations](https://skmtc.dev/cosmicephemeris/apis/cosmic-ephemeris-calculation-api/llms.txt) · [OpenAPI document](https://skmtc.dev/cosmicephemeris/apis/cosmic-ephemeris-calculation-api/revisions/f041e924cea3?raw)