{
 "id": "source/bss-sundial-equations",
 "class": "source",
 "slug": "bss-sundial-equations",
 "label": {
  "ar": "جمعية الساعات الشمسية البريطانية: معادلات",
  "en": "British Sundial Society: Equations",
  "ur": "برطانوی سن ڈائل سوسائٹی: مساوات"
 },
 "summary": {
  "ar": "مرجع حديث لزاوية خطوط الساعات والقطب وتمييز أنظمة الزمن، لا نص ابن الشاطر.",
  "en": "Modern hour-line/style-angle and time-system reference, not Ibn al-Shatir's text.",
  "ur": "گھنٹہ خطوط، محور زاویہ و نظام وقت کا جدید مرجع، ابن شاطر کا متن نہیں۔"
 },
 "stub": false,
 "wings": [],
 "regions": [],
 "periods": [],
 "tags": [],
 "aliases": [],
 "themes": [],
 "data": {
  "kind": "secondary",
  "type": "book",
  "title": "BSS Sundial Glossary and Sourcebook of Dialling Data: Equations Excerpt, Third Edition",
  "author": [
   {
    "literal": "The British Sundial Society; editor John Davis"
   }
  ],
  "publisher": "The British Sundial Society",
  "issued": {
   "date-parts": [
    [
     2020
    ]
   ]
  },
  "language": "en",
  "URL": "https://sundialsoc.org.uk/documents/BSS_Glossary_Equations.pdf",
  "open_access": true,
  "reliability_note": "Actual institutional equations landing page and selected PDF cover/colophon/printed39–41 read, printed41 visually checked. Third edition2020 per colophon, not PDF file's2024 metadata date. Horizontal SH=latitude and X=atan(sin(latitude)*tan(hour angle)); local apparent hour convention, afternoon positive and−90<h<90 branch explicit. Phi30 teaching calculation modern, not medieval layout reconstruction or actual Damascus survey. No copyrighted page/figure/text republished; only cited facts/formula paraphrased. Remaining excerpt equations not claimed as full reading.",
  "status": {
   "review": "published",
   "completeness": 3,
   "generated_by": "Copilot SDK in VS Code"
  },
  "provenance": {
   "generated_by": "Copilot SDK in VS Code",
   "model": "unknown",
   "run": "inventions-p3-b65",
   "source": "Actual selected BSS PDF symbols/time definitions/horizontal formula and institutional landing page"
  }
 },
 "prose": {},
 "degree": 0,
 "contemporaries": [],
 "updated": "2026-11-06",
 "connections": [],
 "related": [],
 "license": {
  "prose": "CC BY-SA 4.0",
  "data": "CC0 1.0"
 }
}