Vedic timekeeping contains questions with more than one respected answer: three sunrise definitions span about seven minutes, ayanāṁśas differ by degrees, and regional schools attribute months to different days. Most software silently picks answers and shows you numbers. We refuse to: every contested question is an explicit setting, a convention presetis a named, sourced bundle of those settings, and every computed result carries a stamp naming the preset that produced it. If our pañcāṅga differs from your family's printed one, you don't have to wonder who is wrong — switch the preset to your tradition and compare like with like.
Rāṣṭrīya Pañcāṅga (Govt. of India)
The Positional Astronomy Centre / Indian Astronomical Ephemeris convention: dṛk gaṇita with the Lahiri ayanāṁśa as fixed by the Calendar Reform Committee (Saha, CSIR 1955), tabulated for the 82°30′E standard meridian. Its rise/set tables state that refraction and semi-diameter are already merged in — and the RP gives that total as −47′, not the −50′ everyone else uses.
The Positional Astronomy Centre / Indian Astronomical Ephemeris convention: dṛk gaṇita with the Lahiri ayanāṁśa as fixed by the Calendar Reform Committee (Saha, CSIR 1955), tabulated for the 82°30′E standard meridian. Its rise/set tables state that refraction and semi-diameter are already merged in — and the RP gives that total as −47′, not the −50′ everyone else uses.
Sources: Calendar Reform Committee report (Saha, CSIR 1955) · research/deep/20-rashtriya-panchang-official-standard.md §4 (h₀ = −47′), §5 · research/deep/21-drik-vs-vakya-and-regional-siddhanta.md §4.2
Krishnamurti Paddhati
K.S. Krishnamurti’s stellar system. Three axes move: the KP ayanāṁśa (Swiss Ephemeris mode 5, ≈348.7″ below Lahiri in 2026), Placidus houses ("the Semi Arc System", KP Reader 1 p.44), and the MEAN node — KP’s tables were built from Raphael’s Ephemeris, which is apparent geocentric with the mean node. Sub and sub-sub lords are emitted for every body and cusp by default.
K.S. Krishnamurti’s stellar system. Three axes move: the KP ayanāṁśa (Swiss Ephemeris mode 5, ≈348.7″ below Lahiri in 2026), Placidus houses ("the Semi Arc System", KP Reader 1 p.44), and the MEAN node — KP’s tables were built from Raphael’s Ephemeris, which is apparent geocentric with the mean node. Sub and sub-sub lords are emitted for every body and cusp by default.
Sources: research/deep/24-kp-krishnamurti-paddhati.md §1.5 (ayanāṁśa), §4.1 (Placidus), §4.3 (mean node) · K.S. Krishnamurti, KP Reader 1, pp. 44, 55-59, 88-89
B. V. Raman
The convention set of B.V. Raman’s Astrological Magazine school: the Raman ayanāṁśa (≈21°25′ in 2000, about 2.3° below Lahiri), Raman’s ṣaḍbala modifications (double Sun Ayana Bala, double Moon Pakṣa Bala), his anti-zodiacal D11, and Raman’s ekādhipatya reduction.
The convention set of B.V. Raman’s Astrological Magazine school: the Raman ayanāṁśa (≈21°25′ in 2000, about 2.3° below Lahiri), Raman’s ṣaḍbala modifications (double Sun Ayana Bala, double Moon Pakṣa Bala), his anti-zodiacal D11, and Raman’s ekādhipatya reduction.
Sources: B.V. Raman, Graha and Bhava Balas · research/raw/09-vargas-and-dashas.md (D11 variants) · packages/jyotisha/src/shadbala.ts option docs
Jagannatha Hora bit-compatibility
Reproduces the choices Jagannatha Hora makes where they differ from the primary-source reading this engine defaults to. Use it when you must match JHora output field-for-field; use `bphs` or `drik` when you want the reading the text actually supports.
Reproduces the choices Jagannatha Hora makes where they differ from the primary-source reading this engine defaults to. Use it when you must match JHora output field-for-field; use `bphs` or `drik` when you want the reading the text actually supports.
Sources: research/raw/09-vargas-and-dashas.md (Vimśopaka weighting readings A and B) · packages/jyotisha/src/vargas.ts VIMSHOPAKA_WEIGHTS commentary
Bṛhat Parāśara Horā Śāstra, literal reading
Every contested axis set to what the text says, including where the text is inconvenient: D60 counted from the SIGN (BPHS’s own worked example does this), the deity lists reversed for even signs, the non-uniform 5-5-8-7-5 trimśāṁśa, and the BPHS ekādhipatya reduction. On the current axis set this coincides with `drik`, which is itself a statement: the modern default IS the textual reading wherever the text is unambiguous.
Every contested axis set to what the text says, including where the text is inconvenient: D60 counted from the SIGN (BPHS’s own worked example does this), the deity lists reversed for even signs, the non-uniform 5-5-8-7-5 trimśāṁśa, and the BPHS ekādhipatya reduction. On the current axis set this coincides with `drik`, which is itself a statement: the modern default IS the textual reading wherever the text is unambiguous.
Sources: BPHS 6.42-53 (varga groups), 7 (trimśāṁśa), Santhanam translation notes · packages/jyotisha/src/vargas.ts DEFAULT_VARGA_OPTIONS commentary
Classical Hindu sunrise (madhyalimba darśana)
Sunrise as the classical texts define it: geocentric disc CENTRE on the mathematical horizon, no refraction (Swiss Ephemeris SE_BIT_HINDU_RISING). About 4 minutes later than the refracted upper-limb sunrise at Indian latitudes, which shifts the vāra boundary, every kāla window and the whole dinamāna/rātrimāna denominator. Offered because some pañcāṅgas genuinely use it — but it is NOT what Drik Panchang’s published day lengths show.
Sunrise as the classical texts define it: geocentric disc CENTRE on the mathematical horizon, no refraction (Swiss Ephemeris SE_BIT_HINDU_RISING). About 4 minutes later than the refracted upper-limb sunrise at Indian latitudes, which shifts the vāra boundary, every kāla window and the whole dinamāna/rātrimāna denominator. Offered because some pañcāṅgas genuinely use it — but it is NOT what Drik Panchang’s published day lengths show.
Sources: research/raw/04-rise-set-transit.md · packages/core-astro/src/riseset.ts SunriseConvention docs
LeoStar / Future Point
The convention set used by LeoStar (Future Point), one of the oldest Indian astrology software houses. Its sunrise is disc CENTRE WITH refraction (h0 = -34′) — a third position, distinct from both Drik Panchang’s refracted upper limb and the classical unrefracted disc centre. Identified by day length, which is immune to their arcminute coordinate rounding: against their published 11:47:11 for Jeypore on 1987-03-05, disc-centre+refraction is +20.0 s while upper-limb is +157.1 s and unrefracted disc-centre is -264.6 s. Matching it reproduces their printed sunrise/sunset to -8 s / +12 s.
The convention set used by LeoStar (Future Point), one of the oldest Indian astrology software houses. Its sunrise is disc CENTRE WITH refraction (h0 = -34′) — a third position, distinct from both Drik Panchang’s refracted upper limb and the classical unrefracted disc centre. Identified by day length, which is immune to their arcminute coordinate rounding: against their published 11:47:11 for Jeypore on 1987-03-05, disc-centre+refraction is +20.0 s while upper-limb is +157.1 s and unrefracted disc-centre is -264.6 s. Matching it reproduces their printed sunrise/sunset to -8 s / +12 s.
Sources: research/05-leostar-validation.md · https://www.leostarastrology.com/sample-horoscope (14_janam-kundli_English.pdf) · packages/validation/src/leostar.test.ts
Tamil (Tirukkaṇita)
The dṛk-gaṇita reckoning used by the overwhelming majority of Tamil pañcāṅgams (Kāñcī ruled for it in 1935; TTD adopted it ≈2014). Numerically difference is the SOLAR MONTH rule: a saṅkrānti before sunset starts the month that day, otherwise the next day. That rule is now implemented and driven by this preset via the `solarDayRule` axis.
The dṛk-gaṇita reckoning used by the overwhelming majority of Tamil pañcāṅgams (Kāñcī ruled for it in 1935; TTD adopted it ≈2014). Numerically difference is the SOLAR MONTH rule: a saṅkrānti before sunset starts the month that day, otherwise the next day. That rule is now implemented and driven by this preset via the `solarDayRule` axis.
Sources: research/deep/21-drik-vs-vakya-and-regional-siddhanta.md §4.2 · research/deep/22-regional-calendar-variants.md §1 (Chatterjee, Tamil school), §2.2
Bengali (Viśuddha Siddhānta)
The Viśuddha Siddhānta Pañjikā line (from 1890): dṛk-siddhānta with Lahiri. The Bengali difference is the month-attribution rule, now driven by this preset, which provably collapses to "civil date of the saṅkrānti + 1 day, always" (research/deep/22 §2.4) — i.e. exactly one day later than the Odia school, every month, forever.
The Viśuddha Siddhānta Pañjikā line (from 1890): dṛk-siddhānta with Lahiri. The Bengali difference is the month-attribution rule, now driven by this preset, which provably collapses to "civil date of the saṅkrānti + 1 day, always" (research/deep/22 §2.4) — i.e. exactly one day later than the Odia school, every month, forever.
Sources: S.K. Chatterjee, Indian Calendric System, pp. 14-15 (Bengal School) · research/deep/22-regional-calendar-variants.md §2.4 (proof), F2
Malayali (Kerala, Kaṇippayyūr)
Dṛk gaṇita with Lahiri, Kerala Parahita tradition. The Kerala difference is the aparāhṇa month rule — the month begins the same day only if the saṅkrānti precedes 3/5 of the daylight span — and this preset drives it.
Dṛk gaṇita with Lahiri, Kerala Parahita tradition. The Kerala difference is the aparāhṇa month rule — the month begins the same day only if the saṅkrānti precedes 3/5 of the daylight span — and this preset drives it.
Sources: S.K. Chatterjee, Indian Calendric System, pp. 14-15 (Malayali School) · research/deep/22-regional-calendar-variants.md §2.2
Nepali (Bikram Sambat)
Orissa-school month attribution computed for Kathmandu at +05:45. The offset is not cosmetic: Karka saṅkrānti 2026 falls at 23:54:22 NPT, six minutes from flipping a month boundary. Note that official BS month lengths are DECREED, not computed — a grid search over 5 rules × 145 offsets reproduces at best 53/60 official month starts, and two of them are mutually contradictory.
Orissa-school month attribution computed for Kathmandu at +05:45. The offset is not cosmetic: Karka saṅkrānti 2026 falls at 23:54:22 NPT, six minutes from flipping a month boundary. Note that official BS month lengths are DECREED, not computed — a grid search over 5 rules × 145 offsets reproduces at best 53/60 official month starts, and two of them are mutually contradictory.
Sources: research/deep/22-regional-calendar-variants.md §7.3, F3, §7 (Nepal)
Śrīpati bhāva
Lahiri with Śrīpati houses, so the chalit bhāva can differ from the rāśi — the classic North Indian bhāva chart.
Traditional / classical
Abhijit printed on Wednesday and Chara read as auspicious, as most printed North Indian pañcāṅgas do.
The machine-readable catalogue — all 18 axes, their legal values and every preset's resolved settings — is published at /api/v1/conventions. An unsupported convention is refused with the list of what would be accepted, never silently substituted. Try any preset live on the pañcāṅga or kundali page.