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get_card_for_birthdate returns five Western/sidereal sign blocks under astro_wheels. They are different systems, not five copies of one answer. On many dates the names match; on others they diverge — that is expected.

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The five wheels

Always read sign_name (and system_slug) on the wheel you care about. Do not treat sign_no as a universal zodiac index — see Field glossary. All five wheels ship in every birth-card payload. Tropical, Vedic, and Fagan-Bradley use equal 30° signs for seasons or tradition. sidereal_iau and sidereal_true use unequal widths that follow constellation position and size on the sky, including Ophiuchus. The cut lines differ; both try to reflect what is actually along the ecliptic. GEOMETRY recommends sidereal_true when you need a default — that is the wheel we use to reflect the sky as closely as we can. Use sidereal_iau for the IAU constellation map; use the equal-sign wheels when your users already expect those systems.

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Why the degrees differ

Each wheel assigns the Sun (and other bodies) to a sign by ecliptic longitude. The degree tables later on this page are the sign boundaries GEOMETRY uses, published in one shared tropical-longitude frame so you can compare them side by side. Same calendar date → same Sun longitude → can land in different named signs when the cuts differ. That is the whole point of returning five wheels. Membership rule: longitude λ is in a sign when start ≤ λ < end, with wrap-through 0° for Pisces on the sidereal equal wheels and IAU (end < start). These boundaries are standard astronomical / traditional reference frames unified in our catalog — not a secret recipe.

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“Wrong sign” is usually the wrong wheel

If a newspaper or app says “Pisces” and astro_wheels.sidereal_true.sign_name says something else (or Ophiuchus), you are comparing different cuts, not catching a GEOMETRY bug. Self-check before filing anything:
  1. Which wheel does your source use (tropical vs Vedic vs Fagan-Bradley vs IAU vs true sidereal)?
  2. Open the matching key under astro_wheels in the raw JSON.
  3. Optionally compare the Sun’s tropical longitude for that date to the degree tables below.
  4. For sky dates (moon / season / retro), also read Calendar boundaries — GMT day vs local almanac is a separate class of “off by one.”

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Degree tables

Wheel order in the tables follows how Aries is placed in the shared tropical-longitude frame — equal 30° wheels first, then unequal IAU and true sidereal. Jump to a table:
  1. tropical
  2. vedic_rasi
  3. fagan_bradley
  4. sidereal_iau
  5. sidereal_true

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tropical (12)

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vedic_rasi (12)

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fagan_bradley (12)

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sidereal_iau (13)

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sidereal_true (13) — preferred

GEOMETRY’s recommended astrology default when you want a 13-sign true-sidereal reading.

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Coverage

All five wheels ship on the published 1900–2100 focus window. See Data coverage.