Research

War Time 1941–45 and Calcutta Time to 1948 shift charts by 23–60 minutes. Our corrections — verified at all four War-Time boundaries, announced on every corrected chart — with the arithmetic in full and the same certificates put to ProKerala, Drik and AstroSage, credit given wherever due.

41% by one rule, 50% by another, 88.7% by the broadest — the Manglik rate is a property of the rule-set, not the population. 10,000 uniform births through our DE440 engine, severity tiers, couple-level cancellation odds, and the astronomical Venus anomaly nobody has published.

±15 minutes flips the ascendant in 1 chart of 8; an hour makes it a coin flip — yet your star and poruthams survive almost anything. All 1,440 minutes computed at two latitudes, the flip-probability law, dasa-shift arithmetic, and the honest triage grid.

South and North India's matching systems reach opposite verdicts for one couple in four and correlate at only r = 0.29. The agreement quadrants, the one perfect 36/36 pairing (a mere 8/12 in porutham), and what cross-regional couples should read first.

The heaviest verdict in guna milan fires at exactly the one-third rate its arithmetic dictates — and 56% of cases cancel under the classical parihāra rules. Plus a new invariant: no surviving nadi dosha exists in an otherwise-strong match.

One couple in five flips between the two Tamil almanac schools — yet nadi agrees 100% and yoni disagrees 64%, proving the divide is inherited matrices, not astronomy. The first measured map, with the five-point Shravana–Magha flip dissected.

The ayanamsa setting silently decides your nakshatra, Moon sign and dasa dates. We measure the gaps between the major conventions and compute exactly how many charts each gap flips — KP−Lahiri moves every dasa boundary by weeks; Raman−Lahiri flips one nakshatra in nine.

The two zodiacs measure the same sky from starting points now ~24°13′ apart. What each system actually measures, the full 2026 conversion table, why Pongal's date is the ayanamsa — and why your rasi was never your Sun sign in the first place.

Apps place Rahu up to 1°45′ apart — different signs ≈3.7% of the time, sign-change dates a month apart, Kala Sarpa verdicts flipping with a setting. Both models stated fairly, and the classical case for the mean node we compute with.

Historical daylight saving is a database, not a number. US War Time, UK double summer time, Singapore 1982, Sri Lanka's two changes, Indiana — the full trap catalogue, with the damage per hour of error quantified and a one-minute test for any tool.

For three years India's clocks ran an hour ahead of IST. Same date, same clock, same city: our engine shows Rishaba lagna in 1943 where 1946 shows Mithuna — the war hour, visible in computation. How to re-check an elder's chart, respectfully.

Tamil Nadu's beloved almanacs run on chantable Sanskrit verses — katapayadi-encoded lunar tables from Vararuci's 248 chandravākyas and the medieval Vākya-karana. How the memorised algorithm works, why its minutes drift, and why temples keep vākya time on purpose.

The received Surya-Siddhanta school versus the drik reform — why the two panjikas' tithis diverge, how fractions of an hour become two festival dates, and how Bengal's argument mirrors Tamil Nadu's vākya-vs-thirukanitha divide.

A solar era whose months are the zodiac, birthdays kept by nakshatra, farming time told in the Sun's 27 fortnights — and Parameshvara's fifteenth-century drik reform: the province that settled the almanac wars six hundred years early.

India's most comprehensive free engine — and we credit it. But two things keep it from the last word: a nuance (it misses US daylight saving, flipping a diaspora birth's star, dasa and ascendant) and accuracy (an arc-second short at a cusp reads Mula where DE440 reads Purva Ashadha). We verify both against JPL DE440 — and reproduce AstroSage's own chart to the arc-second.

Clickastro is the direct brand of Astro-Vision — the Kochi engine other sites resell. We reproduced its own Super Horoscope against our DE440 engine to the arc-second, so the math is settled. The critique is access: the free tier gives a correct chart and a matching teaser, routing every koota, dosha and prediction into a Rs 399+ funnel of reports, consultations and pujas. We show the same depth, free.

Verified against our DE440 engine, ProKerala handles US daylight saving correctly — matching us to ~15 seconds on a boundary birth. Its paid Rs 999 report (an Astro-Vision LifeSign document) is comprehensive but a fifty-page data dump; we keep all of it, reorganised into six reader-facing sections, free.

We don't only flag errors. Verified against our own engine, drikpanchang handles location, timezone and daylight saving correctly — the first reference in this series to pass every check.

A strong, free Drik-based Tamil almanac — and a demonstrated weakness: omitting DST can move a boundary birth into a different nakshatra or rasi, changing the match.

Unusually rich, forgiving gendered matching — undermined in the matching tool by a forced Local Mean Time correction that over-precises clock-recorded births.