{
  "default": "pac-rp",
  "profiles": [
    {
      "id": "pac-rp",
      "version": "2026.1",
      "title": "Rashtriya Panchang",
      "purpose": "Parity with the Positional Astronomy Centre and the Rashtriya Panchang.",
      "ayanamsa": "lahiri-iae1985",
      "solarAyanamsa": "fixed-23-15",
      "rise": {
        "sun": {
          "limb": "upper",
          "refractionArcmin": 31,
          "semidiameter": 16,
          "dip": false
        },
        "moon": {
          "limb": "centre",
          "refractionArcmin": 31,
          "semidiameter": 16,
          "dip": false
        }
      },
      "kala": {
        "arunodaya": "prev-night-muhurta-14-15",
        "pratah": "day-muhurta-1-3",
        "sangava": "day-muhurta-4-6",
        "madhyahna": "midday-pm-1-ghatika",
        "aparahna": "day-muhurta-10-12",
        "sayahna": "day-muhurta-13-15",
        "pradosha": "night-muhurta-1-2",
        "nishita": "midnight-pm-1-ghatika"
      },
      "monthSystem": "amanta",
      "dayBoundary": "sunrise",
      "notes": [
        "Moonrise and moonset: the sources read do not state the Rashtriya Panchang convention; the centre of the disc with 31′ refraction is assumed.",
        "Pradoṣa and aruṇodaya are two muhūrtas of the night (one fifteenth of the night each), which the CRC text glosses as \"about 4 ghatikas\"."
      ]
    },
    {
      "id": "classical",
      "version": "2026.1",
      "title": "Classical sunrise",
      "purpose": "The traditional sunrise: centre of the disc on the geometric horizon, no refraction.",
      "ayanamsa": "lahiri-iae1985",
      "solarAyanamsa": "fixed-23-15",
      "rise": {
        "sun": {
          "limb": "centre",
          "refractionArcmin": 0,
          "semidiameter": 16,
          "dip": false
        },
        "moon": {
          "limb": "centre",
          "refractionArcmin": 31,
          "semidiameter": 16,
          "dip": false
        }
      },
      "kala": {
        "arunodaya": "prev-night-muhurta-14-15",
        "pratah": "day-muhurta-1-3",
        "sangava": "day-muhurta-4-6",
        "madhyahna": "midday-pm-1-ghatika",
        "aparahna": "day-muhurta-10-12",
        "sayahna": "day-muhurta-13-15",
        "pradosha": "night-muhurta-1-2",
        "nishita": "midnight-pm-1-ghatika"
      },
      "monthSystem": "amanta",
      "dayBoundary": "sunrise",
      "notes": [
        "Moonrise and moonset: the sources read do not state the Rashtriya Panchang convention; the centre of the disc with 31′ refraction is assumed."
      ]
    },
    {
      "id": "iskcon-gcal",
      "version": "2026.1",
      "title": "Vaiṣṇava (GCal)",
      "purpose": "The astronomical basis for Vaiṣṇava rulings reconciled to the Gaurabda Calendar.",
      "ayanamsa": "lahiri-iae1985",
      "solarAyanamsa": "fixed-23-15",
      "rise": {
        "sun": {
          "limb": "upper",
          "refractionArcmin": 31,
          "semidiameter": 16,
          "dip": false
        },
        "moon": {
          "limb": "centre",
          "refractionArcmin": 31,
          "semidiameter": 16,
          "dip": false
        }
      },
      "kala": {
        "arunodaya": "sunrise-minus-4-ghatika",
        "pratah": "day-muhurta-1-3",
        "sangava": "day-muhurta-4-6",
        "madhyahna": "midday-pm-1-ghatika",
        "aparahna": "day-muhurta-10-12",
        "sayahna": "day-muhurta-13-15",
        "pradosha": "night-muhurta-1-2",
        "nishita": "midnight-pm-1-ghatika"
      },
      "monthSystem": "amanta",
      "dayBoundary": "sunrise",
      "notes": [
        "Only aruṇodaya (4 ghaṭikās before sunrise) is set from the source so far; the rise model and month naming are those of pac-rp until reconciled against GCal output.",
        "Moonrise and moonset: the sources read do not state the Rashtriya Panchang convention; the centre of the disc with 31′ refraction is assumed."
      ]
    },
    {
      "id": "compat-drikpanchang",
      "version": "2026.1",
      "title": "Comparison: DrikPanchang",
      "purpose": "Comparison only, never a default: the conventions inferred from that site’s printed values.",
      "ayanamsa": "lahiri-iae1985",
      "solarAyanamsa": "lahiri-iae1985",
      "rise": {
        "sun": {
          "limb": "upper",
          "refractionArcmin": 34,
          "semidiameter": "true",
          "dip": false
        },
        "moon": {
          "limb": "centre",
          "refractionArcmin": 0,
          "semidiameter": "true",
          "dip": false
        }
      },
      "kala": {
        "arunodaya": "prev-night-muhurta-14-15",
        "pratah": "day-muhurta-1-3",
        "sangava": "day-muhurta-4-6",
        "madhyahna": "day-muhurta-7-9",
        "aparahna": "day-muhurta-10-12",
        "sayahna": "day-muhurta-13-15",
        "pradosha": "night-muhurta-1-3",
        "nishita": "night-muhurta-8"
      },
      "monthSystem": "purnimanta",
      "dayBoundary": "sunrise",
      "notes": [
        "The site prints an ayanāṃśa about 15″ larger than lahiri-iae1985 and does not define it; saṅkrānti instants can differ by several minutes.",
        "Aruṇodaya is not defined by the site; two night muhūrtas are assumed. The Moon convention rests on one city-day."
      ]
    }
  ],
  "models": {
    "ephemeris": "JPL DE440, SPK type 2 excerpt (Sun, Earth-Moon barycentre, Moon); Earth from EMRAT",
    "precession": "IAU 2006, Fukushima-Williams angles with frame bias",
    "nutation": "IAU 2000B (77 luni-solar terms)",
    "siderealTime": "Earth rotation angle + IAU 2006 GMST + equation of the equinoxes",
    "aberration": "annual, special-relativistic; light-time iterated",
    "earthFigure": "WGS84",
    "deltaT": {
      "source": "US Naval Observatory, https://maia.usno.navy.mil/ser7/ (historic_deltat.data, deltat.data)",
      "tableVersion": "usno-ser7-2026-10-15",
      "lastTabulated": "2026-10-01",
      "extrapolation": "beyond the table: last value + its mean rate over the final 10 years + ½·0.0065 s/yr²·τ²"
    },
    "leapSeconds": {
      "tableVersion": "usno-ser7-2026-10-15",
      "lastStep": "2017-01-01",
      "assumption": "no leap second after the last step; before 1972 the input is read as UT1"
    },
    "omitted": [
      "gravitational light deflection (< 0.01″ for the Moon, nil for the Sun)",
      "diurnal aberration (≤ 0.32″, topocentric only)",
      "polar motion (≤ 0.3″ in altitude, up to 0.3″·tan φ in azimuth; topocentric only)"
    ]
  },
  "engine": {
    "version": "0.1.0",
    "ruleset": "2026.3-draft",
    "kernel": "de440-1900-2100",
    "kernel_sha256": "7eef444f9e5bd8786b8b5b72e775ecc376991b953a6246ec7a49d2c37434ea74",
    "tzdata": "2026f"
  }
}