Panchang Calculator

The Panchang Calculator is a JavaScript library for calculating various elements of the Hindu Panchang (calendar), such as Tithi, Nakshatra, Karana, Yoga, and Raasi. It uses both traditional Vedic and modern astronomical methods to provide accurate results. Additionally, it includes support for converting Gregorian dates to the Bikram Sambat (Vikram Sambat) calendar, the traditional Nepali calendar.

Features

Panchang Calculations:
- Tithi: Lunar day based on the angular distance between the Moon and Sun.
- Nakshatra: Lunar mansion based on the Moon's position.
- Karana: Half of a Tithi.
- Yoga: Combination of the Sun and Moon's positions.
- Raasi: Zodiac sign based on the Moon's position.
Bikram Sambat Conversion:
- Converts Gregorian dates to the Bikram Sambat calendar.
- Supports all timezones automatically using the JavaScript Date object.
- Uses sunrise-based day boundaries for accurate results.
Astronomical Precision:
- Calculates the Sun and Moon's positions using modern astronomical algorithms.
- Accounts for precession (ayanamsa) and nutation.
Timezone Support:
- Automatically adjusts for the local timezone using the JavaScript Date object.

Installation

You can install the library via npm:

npm install panchang-calculator

Or include it directly in your project:

<script src="path/to/panchang.js"></script>

Usage

1. Panchang Calculation

import { PanchangCalculator } from "panchang-calculator";

const date = new Date(); // Current date
const panchang = new PanchangCalculator().calculate(date);

console.log(panchang);

Example Output:

{
  "day": { "name": "Sunday" },
  "tithi": {
    "name": "Shukla Paksha Pratipada",
    "start": "2023-10-15T06:00:00.000Z",
    "end": "2023-10-16T06:30:00.000Z"
  },
  "nakshatra": {
    "name": "Ashwini",
    "start": "2023-10-15T06:00:00.000Z",
    "end": "2023-10-16T06:30:00.000Z"
  },
  "karana": {
    "name": "Bava",
    "start": "2023-10-15T06:00:00.000Z",
    "end": "2023-10-15T18:00:00.000Z"
  },
  "yoga": {
    "name": "Vishkambha",
    "start": "2023-10-15T06:00:00.000Z",
    "end": "2023-10-16T06:30:00.000Z"
  },
  "raasi": { "name": "Aries" },
  "ayanamsa": { "name": "23° 51' 12\"" }
}

2. Bikram Sambat Conversion

import { gregorianToBS, formatBSDate } from "panchang-calculator";

const date = new Date(2023, 11, 26); // December 26, 2023
const bsDate = gregorianToBS(date);

console.log(formatBSDate(bsDate)); // "11 Poush 2080"

Example Output:

11 Poush 2080

3. Custom Location (Sunrise Calculation)

If you want to use a specific location for sunrise calculations (e.g., Kathmandu), you can override the default sunrise function:

import { gregorianToBS, formatBSDate } from "panchang-calculator";

function getKathmanduSunrise(date) {
  // Custom sunrise calculation for Kathmandu
  const dayOfYear = Math.floor(
    (date.getTime() - new Date(date.getFullYear(), 0, 0).getTime()) / 86400000
  );
  const approxSunrise = 6.5; // Average sunrise time in Nepal
  const variation = 0.5 * Math.sin((2 * Math.PI * (dayOfYear - 80)) / 365); // Seasonal adjustment
  return (approxSunrise + variation + 5.75) / 24; // UTC+5:45
}

const date = new Date(2023, 11, 26); // December 26, 2023
const bsDate = gregorianToBS(date, getKathmanduSunrise);

console.log(formatBSDate(bsDate)); // "11 Poush 2080"

API Reference