---
title: "Calculate Natal Transits"
method: POST
path: "/comparative/natal-transits"
tags: ["comparative"]
---

# Calculate Natal Transits

`POST /comparative/natal-transits`

## Request

- Base URL: `https://api.openephemeris.com`
- URL: `https://api.openephemeris.com/comparative/natal-transits`
- Auth: one of:
  - HTTP bearer
  - API key in header `X-OpenEphemeris-API-Key`
  - API key in header `X-API-Key`
  - API key in header `X-Service-Key`

Calculate a synastry-style overlay between a natal chart and transits.

- Chart A: natal subject at birth
- Chart B: the same subject/location at transit_datetime (defaults to now UTC)

## Query parameters

- `format` string

## Request body

- NatalTransitsRequest: Transit overlay request using a natal subject plus a target datetime.
  - `configuration` ChartConfiguration: Legacy configuration model. New integrations should use NatalConfig with object_set and node_source instead of include_* booleans.
    - `additional_objects` string[]: Explicit body slugs to compute in addition to the base 10-planet roster (comparative/synastry and comparative/composite only compute the classical planets by default). Ephemeris body slugs: sun, moon, mercury, venus, mars, jupiter, saturn, uranus, neptune, pluto, north_node, true_node, lilith, lilith_true, lilith_interpolated, chiron, pholus, eris, sedna, makemake, haumea, quaoar, orcus, ixion, varuna, cupido, hades, zeus, kronos, apollon, admetos, vulkanus, poseidon, eros, sappho, lilith_asteroid, nessus, chariklo, amor, betulia, icarus, apollo, adonis, phaethon, astraea, hebe, flora, metis, parthenope, victoria, egeria, irene, massalia, isis, anubis, odysseus, tolosa, medusa, ambrosia, aletheia, thule, polyxo, myrrha, valentine, hercynia, nestor, siva, atlantis, aphrodite, prometheus, epimetheus, shaposhnikov, lick, huya, ceres, pallas, juno, vesta, hygiea, eunomia, psyche, europa_asteroid, cybele, sylvia, thisbe, camilla, iris, davida, euphrosyne, interamnia. Unknown slugs are ignored.
    - `ascendant_on_left` boolean: When true (default), the Ascendant is placed at the 9 o'clock (West/left) position � matching the convention used by Astro.com, Solar Fire, and all major astrology software. Set to false to use the ecliptic-fixed (Aries-pinned) orientation instead.
    - `aspect_orbs` object: Caller-supplied orb allowances in degrees, keyed by aspect name (conjunction, opposition, trine, square, sextile, and the minors quincunx, semisextile, semisquare, sesquiquadrate, quintile, biquintile). Overrides the default table for the aspects named; aspects not named keep their defaults, and naming a minor is what turns it on. An unknown aspect name is rejected with 422 rather than ignored, because a silently dropped override returns a chart scored against a table the caller did not choose. Setting an orb to 0 turns that aspect off entirely. Honoured on the routes that compute an aspect grid: /comparative/composite, /comparative/natal-transits, /comparative/synastry and /ephemeris/progressed.
    - `asteroid_groups` AsteroidGroupEnum[]: Optional thematic asteroid groups to include, additive on top of the base 10-planet roster: major (Ceres/Pallas/Juno/Vesta), centaur (Chiron/Pholus), main_belt (the 12 sb441-n16 minor asteroids), tno (the 8 trans-Neptunian objects: Eris, Sedna, Makemake, Haumea, Quaoar, Orcus, Ixion, Varuna). muse is accepted but not yet computed (no kernel loaded).
    - `ayanamsa` string: Ayanamsa for sidereal calculations
    - `house_system` 'P' | 'K' | 'O' | 'R' | 'C' | 'E' | 'W': Supported house systems.
    - `include_chiron` boolean: Include Chiron in calculations
    - `include_lilith` boolean: Include Black Moon Lilith
  - `enhanced_options` EnhancedCalculationOptions: Options for enhanced natal chart calculations.
    - `aspect_patterns` boolean: Identify aspect patterns
    - `element_balance` boolean: Calculate elemental balance
    - `elongations` boolean: Compute Sun-relative elongation metrics for major bodies (separation, signed delta, east/west).
    - `harmonic_numbers` integer[]: Harmonic numbers to calculate (default: [4, 5, 7, 9])
    - `hemisphere_emphasis` boolean: Analyze hemisphere emphasis
    - `hermetic_lots_selection` string[]: Optional list of Hermetic lot identifiers to calculate (aliases accepted: arabic_parts_selection). If omitted, defaults to the canonical selection.
    - `human_design_gates` boolean: Compute Human Design / I Ching gate + line mappings from ecliptic longitude.
    - `include_fixed_stars` boolean: DEPRECATED. Fixed-star computation is configured via configuration.fixed_star_options.include. This field is accepted for backward compatibility and may be removed in a future release.
    - `include_harmonics` boolean: Include harmonic chart positions
    - `include_hermetic_lots` boolean: Calculate Hermetic lots
    - `include_midpoints` boolean: Calculate midpoints between planet pairs
    - `lunar_phase` boolean: Compute lunar phase (name, illumination, phase angle, waxing/waning, and days-to-new/full).
    - `sect_determination` boolean: Perform sect determination
    - `solar_relationships` boolean: Compute solar relationship / visibility classifications (e.g., cazimi/combust/under-beams) and Mercury/Venus morning/evening star context.
    - `void_of_course` boolean: Compute Void-of-Course Moon status and window (bounded search within current sign).
  - `include_visual` boolean: If true, a full visual SVG or PNG output will be rendered and returned alongside the chart data. Note: Visuals incur a +2 credit surcharge.
  - `subject` SubjectRequest, required: Subject identity and birth data used to compute a chart.
    - `birth_datetime` DateTimeInput, required: Date/time input in ISO-8601, component, or Julian day form. A value that states a clock time must also state its zone, either as a suffix on the string or via the `timezone` field below.
      - `components` object: Date/time components (year, month, day, and optionally hour, minute, second). If hour/minute are present, pass `timezone` alongside them; without it the request is rejected with 400 ambiguous_datetime. Omit the clock entirely and the date resolves to 12:00 UTC.
      - `iso` string: ISO-8601 datetime (supported range 1550–2650 CE, JPL DE440). If it states a clock time it must carry its zone: either a 'Z'/±HH:MM suffix on the string ("1987-07-15T09:01:00-05:00"), or a `timezone` passed alongside it. A zone-less clock time is rejected with 400 ambiguous_datetime — it is not read as UTC. A date-only value ("1987-07-15") has no clock to be ambiguous about and resolves to 12:00 UTC.
      - `julian_day` number, double: Julian Day Number (always UTC-based, so it needs no zone)
      - `timezone` TimezoneInput: Timezone input using IANA names or UTC offsets.
        - `fold_preference` 'earlier' | 'later': Which occurrence to use when the naive local datetime falls in a fall-back fold (a repeated hour): 'earlier' (default — first occurrence) or 'later'. Only meaningful for naive datetimes; the response reports datetime_status=ambiguous_fold either way so the ambiguity can be surfaced to the user.
        - `iana_name` string: IANA timezone name
        - `time_standard` 'auto' | 'standard' | 'daylight': How to interpret a naive local datetime when this zone is applied. 'auto' (default): resolve through the historical-correction overlay where one covers the region/era, then IANA tzdata. 'standard': force the zone's standard (non-daylight) offset — for callers who KNOW the recorded time was standard time regardless of what tzdata believes. 'daylight': force standard+1h. Forcing either marks the resolution tz_confidence=client_override. Ignored when the datetime carries its own Z/±HH:MM suffix or when utc_offset is used.
        - `utc_offset` number: UTC offset in hours
    - `birth_location` BirthLocation, required: Location context for birth data: coordinates plus timezone.
      - `city` string: City name
      - `country` string: Country
      - `elevation` number: Elevation in meters. Accepted and echoed back unchanged; it does not affect planetary positions, which are computed geocentrically. Elevation changes results only where it is taken as the `elev` query parameter: /eclipse/solar/local (local circumstances) and /time/solar-event plus /ephemeris/agro/* (horizon rise/set times).
      - `latitude` CoordinateInput, required: Flexible coordinate input supporting multiple formats.
        - `components` object: Separate degree components with direction
        - `decimal` number: Decimal degrees (-90 to 90 for lat, -180 to 180 for lon)
        - `dms` string: Degrees, minutes, seconds string (e.g., '40°42'46"N')
      - `location_name` string: Birthplace display name (e.g. "Dallas, TX"). Never affects calculations — coordinates and timezone are the only location facts the engine reads. Echoed back verbatim where the response carries an echo block: as subject.location_name on chart routes that echo a subject (natal, draconic, progressed, synastry, natal-transits, overlay, natal/batch items, predictive transit-chart), inside search_summary on /electional/natal-angle-crossings, metadata on /acg/midpoints, and natal on /human-design/transit-chart. Omitted from the response when not sent.
      - `longitude` CoordinateInput, required: Flexible coordinate input supporting multiple formats.
        - `components` object: Separate degree components with direction
        - `decimal` number: Decimal degrees (-90 to 90 for lat, -180 to 180 for lon)
        - `dms` string: Degrees, minutes, seconds string (e.g., '40°42'46"N')
      - `region` string: State/region
      - `timezone` TimezoneInput, required: Timezone input using IANA names or UTC offsets.
        - `fold_preference` 'earlier' | 'later': Which occurrence to use when the naive local datetime falls in a fall-back fold (a repeated hour): 'earlier' (default — first occurrence) or 'later'. Only meaningful for naive datetimes; the response reports datetime_status=ambiguous_fold either way so the ambiguity can be surfaced to the user.
        - `iana_name` string: IANA timezone name
        - `time_standard` 'auto' | 'standard' | 'daylight': How to interpret a naive local datetime when this zone is applied. 'auto' (default): resolve through the historical-correction overlay where one covers the region/era, then IANA tzdata. 'standard': force the zone's standard (non-daylight) offset — for callers who KNOW the recorded time was standard time regardless of what tzdata believes. 'daylight': force standard+1h. Forcing either marks the resolution tz_confidence=client_override. Ignored when the datetime carries its own Z/±HH:MM suffix or when utc_offset is used.
        - `utc_offset` number: UTC offset in hours
    - `gender` string: Gender (optional)
    - `name` string, required: Subject name
    - `notes` string: Additional notes
  - `transit_datetime` DateTimeInput: Date/time input in ISO-8601, component, or Julian day form. A value that states a clock time must also state its zone, either as a suffix on the string or via the `timezone` field below.
    - `components` object: Date/time components (year, month, day, and optionally hour, minute, second). If hour/minute are present, pass `timezone` alongside them; without it the request is rejected with 400 ambiguous_datetime. Omit the clock entirely and the date resolves to 12:00 UTC.
    - `iso` string: ISO-8601 datetime (supported range 1550–2650 CE, JPL DE440). If it states a clock time it must carry its zone: either a 'Z'/±HH:MM suffix on the string ("1987-07-15T09:01:00-05:00"), or a `timezone` passed alongside it. A zone-less clock time is rejected with 400 ambiguous_datetime — it is not read as UTC. A date-only value ("1987-07-15") has no clock to be ambiguous about and resolves to 12:00 UTC.
    - `julian_day` number, double: Julian Day Number (always UTC-based, so it needs no zone)
    - `timezone` TimezoneInput: Timezone input using IANA names or UTC offsets.
      - `fold_preference` 'earlier' | 'later': Which occurrence to use when the naive local datetime falls in a fall-back fold (a repeated hour): 'earlier' (default — first occurrence) or 'later'. Only meaningful for naive datetimes; the response reports datetime_status=ambiguous_fold either way so the ambiguity can be surfaced to the user.
      - `iana_name` string: IANA timezone name
      - `time_standard` 'auto' | 'standard' | 'daylight': How to interpret a naive local datetime when this zone is applied. 'auto' (default): resolve through the historical-correction overlay where one covers the region/era, then IANA tzdata. 'standard': force the zone's standard (non-daylight) offset — for callers who KNOW the recorded time was standard time regardless of what tzdata believes. 'daylight': force standard+1h. Forcing either marks the resolution tz_confidence=client_override. Ignored when the datetime carries its own Z/±HH:MM suffix or when utc_offset is used.
      - `utc_offset` number: UTC offset in hours
  - `visual_config` VisualRenderConfig: Optional rendering preferences for inline chart visuals.
    - `format` 'svg' | 'png': Output encoding: "svg" (default) or "png". PNG requires resvg on the server.
    - `layout` 'graph' | 'mandala': Bodygraph composition: "graph" (default) is the classic layout; "mandala" nests the same diagram inside concentric rings. Ignored for wheel renders. Honored on natal and overlay (transit, connection) bodygraph paths.
    - `size` integer: Canvas pixel dimension. Range [200, 4000]. Default 800.
    - `theme` 'light' | 'dark': Colour palette: "light" (default) or "dark".

## Response `200`

Successful Response

- NatalTransitsResponse: Response for natal-to-transits overlay.
  - `aspects` AspectResponse[], required: Cross-aspects between natal and transits
    - `angle` number, required: Aspect angle in degrees
    - `applying` boolean, required: Is aspect applying
    - `aspect` string, required: Aspect name
    - `object1` string, required: First object name
    - `object2` string, required: Second object name
    - `orb` number, required: Orb in degrees
  - `chart_a` LightChartResponse, required: Lightweight chart representation for overlay-style comparisons. Includes houses + angles to support chart rendering in comparative responses.
    - `angles` AnglesResponse, required: Chart angles data in response.
      - `ascendant` number, required: Ascendant longitude in degrees
      - `descendant` number, required: Descendant longitude in degrees
      - `imum_coeli` number, required: Imum Coeli longitude in degrees
      - `midheaven` number, required: Midheaven longitude in degrees
    - `houses` HousesResponse, required: House system data in response.
      - `cusps` number[], required: House cusp longitudes in degrees
      - `system` string, required: House system code
    - `planets` object, required: Planetary positions keyed by name
    - `subject` SubjectResponse, required: Normalized subject data in response.
      - `altitude` number, required: Altitude in meters
      - `datetime` string, required: ISO format datetime
      - `julian_day` number, double, required: Julian Day Number
      - `latitude` number, required: Latitude in decimal degrees
      - `longitude` number, required: Longitude in decimal degrees
      - `name` string, required: Subject name
      - `timezone_name` string: Timezone name if available
      - `utc_offset` number: UTC offset in hours
  - `chart_b` LightChartResponse, required: Lightweight chart representation for overlay-style comparisons. Includes houses + angles to support chart rendering in comparative responses.
    - `angles` AnglesResponse, required: Chart angles data in response.
      - `ascendant` number, required: Ascendant longitude in degrees
      - `descendant` number, required: Descendant longitude in degrees
      - `imum_coeli` number, required: Imum Coeli longitude in degrees
      - `midheaven` number, required: Midheaven longitude in degrees
    - `houses` HousesResponse, required: House system data in response.
      - `cusps` number[], required: House cusp longitudes in degrees
      - `system` string, required: House system code
    - `planets` object, required: Planetary positions keyed by name
    - `subject` SubjectResponse, required: Normalized subject data in response.
      - `altitude` number, required: Altitude in meters
      - `datetime` string, required: ISO format datetime
      - `julian_day` number, double, required: Julian Day Number
      - `latitude` number, required: Latitude in decimal degrees
      - `longitude` number, required: Longitude in decimal degrees
      - `name` string, required: Subject name
      - `timezone_name` string: Timezone name if available
      - `utc_offset` number: UTC offset in hours
  - `visual` VisualResult: Embedded diagram payload returned alongside chart data when include_visual=true.
    - `content_type` string, required: MIME type of the data payload.
    - `credits_charged` integer, required: Additional credits consumed to render the visual: 2, or 0 on a re-render that presented a valid render_token.
    - `data` string, required: Raw SVG string (format=svg) or standard base64-encoded PNG bytes (format=png, no data: URI prefix).
    - `format` string, required: Output format: "svg" or "png".
    - `render_token` string: Short-lived (15 min) token for re-rendering this same chart. Send it back in the X-OE-Render-Token header (or a top-level render_token body field) with a request for the same chart inputs — e.g. the same birth data in a different theme or layout — and that request is not charged again. Bound to your account and to the chart-defining inputs; any other request is charged normally.
    - `type` string, required: Diagram kind: "wheel" or "bodygraph".

## Other responses

- `422`: Validation Error

---

[API](https://skmtc.dev/openephemeris/apis/open-ephemeris-api.md) · [All operations](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/llms.txt) · [OpenAPI document](https://skmtc.dev/openephemeris/apis/open-ephemeris-api/revisions/d195a769cb89?raw)