Panchang API Accuracy: Verified Against Drikpanchang.com for Every Timezone on Earth

The standard we held ourselves to

Drikpanchang.com is the most widely trusted Panchang reference on the internet. Millions of users in India check it daily. Professional astrologers cite it. Temples use it. If your API does not match Drikpanchang, it does not match reality.

Most Vedic astrology APIs are built for Indian cities only and tested only against IST. The moment a developer in New York, Sydney, or Auckland calls the same endpoint, the times are wrong — sometimes by hours — because the computation was never designed with UTC in mind.

We built VedIntel™ AstroAPI differently. Swiss Ephemeris runs locally. All times are returned in UTC with Unix timestamps. Timezone conversion is the developer's responsibility, not ours. And every computation is verified — not just for India, but for every timezone on earth.

The verification — 7 cities, head to head

Below is the raw comparison. API values converted to local time, placed next to Drikpanchang. These are not cherry-picked cities — they were chosen specifically to stress-test edge cases: quarter-hour UTC offset (Kathmandu), DST (Sydney), negative UTC (New York), polar day (Reykjavik), and the International Date Line (Auckland).

The 1-minute residual on some values is Drikpanchang's own display rounding — it shows HH:MM with no seconds. The underlying Swiss Ephemeris computation is exact. Mumbai was independently verified with full seconds precision: Sunrise 06:00:16 IST, Sunset 19:15:36 IST, Rahu Kaal 12:37:56–14:17:21 IST — all matching exactly.

Edge cases that break most APIs

Quarter-hour timezone offset — Kathmandu (UTC+5:45)

Nepal Standard Time is UTC+5:45 — not a whole hour, not a half hour. Many APIs hardcode 30-minute offsets and silently return wrong times for Nepal. We pass tz=5.75 and compute correctly. Sunrise matches Drikpanchang exactly.

Daylight Saving Time — Sydney (UTC+10 winter, UTC+11 summer)

Sydney observes AEST (UTC+10) in winter and AEDT (UTC+11) in summer. A developer building an Australian astrology app needs to pass the correct offset for the date. Our API accepts the offset as a parameter — it does not try to auto-detect DST, which would be a source of bugs. Both winter and summer results match Drikpanchang within 1 minute.

Polar day — Reykjavik (UTC+0, 21 hours of daylight in June)

On June 10, Reykjavik has sunrise at 03:04 and sunset at 23:51 — nearly 21 hours of daylight. Rahu Kaal spans 13:28–16:04, a 2.5-hour window. Most Vedic astrology APIs are never tested for polar latitudes and return null or garbage. Ours computes correctly.

International Date Line — Auckland (UTC+12)

Auckland sits at UTC+12, meaning its calendar day starts 12 hours ahead of UTC. Sunrise and sunset in Auckland's local time can correspond to the previous or next UTC calendar day. Computing Panchang here requires getting the day boundaries exactly right. We verified: 07:29 sunrise (API) vs 07:30 (Drikpanchang) — 1-minute rounding only.

Negative UTC — New York (UTC−4 EDT)

Western hemisphere cities have negative timezone offsets. tz=-4.0 for New York in June (Eastern Daylight Time). Sunrise 05:24, Sunset 20:26 — exact match on sunrise, 1-minute rounding on sunset and Rahu Kaal.

How the computation works

Every Panchang value is computed by Swiss Ephemeris running locally on our servers — no third-party API calls, no external dependencies. Sunrise and sunset use swe_rise_trans() with the SE_BIT_NO_REFRACTION flag, which is the Vedic panchang convention (atmospheric refraction excluded, matching how traditional almanacs are computed).

All times are returned in UTC with Unix timestamps. No local time conversion happens on our side — that is intentional. A developer in Auckland, New York, and Mumbai all get the same UTC value for the same astronomical event. They convert to their user's local time using standard timezone libraries. This is the global industry standard and the only approach that works correctly for every city on earth.

Response format

{
  "sunrise": { "utc": "00:30:16", "unix": 1781051416 },
  "sunset":  { "utc": "13:45:36", "unix": 1781099136 },
  "rahu_kaal": {
    "start_utc":  "07:07:56",
    "start_unix": 1781075276,
    "end_utc":    "08:47:21",
    "end_unix":   1781081241
  }
}

Converting to local time in JavaScript: new Date(unix * 1000).toLocaleTimeString('en-IN', { timeZone: 'Asia/Kolkata' })

667 automated regression tests — on every deployment

Accuracy is not a one-time claim. It needs to stay accurate as the codebase evolves. We maintain 667 automated integration checks that run on every push to production:

• ✓ HTTP 200 on every endpoint
• ✓ Every time field returns {utc, unix} — never a plain string
• ✓ UTC and Unix timestamps are internally consistent
• ✓ No AM/PM strings anywhere in any response (recursive scan)
• ✓ Choghadiya returns exactly 8 daytime and 8 nighttime slots with no gaps
• ✓ Rahu Kaal, Yamagandam, Gulikai all fall within sunrise–sunset
• ✓ Brahma Muhurta ends before sunrise
• ✓ Birmingham sunrise locked to 03:45:xx UTC (Drikpanchang-verified)
• ✓ All 9 edge case cities snapshotted and enforced on every future run

If any future code change causes a regression — even 1 minute off on Reykjavik — the deployment fails automatically. No manual testing required.

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