Berikut adalah seri postingan tentang astronomi praktis. Seri ini memiliki tujuan akhir yaitu membuat class Java yang berisi perhitungan-perhitungan dari buku Practical Astronomy with your calculator or spreadsheet 4th Edition by Peter Duffett and Jonathan Zwart.
Kali ini menghitung Julian Day dari kalender gregorian day.
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| public class ShowJulianDay | |
| { | |
| // arguments are passed using the text field below this editor | |
| public static void main(String[] args) | |
| { | |
| PracticalAstronomy astro = new PracticalAstronomy(2009,6,19,18,0,0); | |
| System.out.print(astro.getJulianDay()); | |
| } | |
| } | |
| public class PracticalAstronomy | |
| { | |
| private int year; | |
| private int month; | |
| private int day; | |
| private int hour; | |
| private int minute; | |
| private int second; | |
| public PracticalAstronomy(int year,int month,int day,int hour,int minute,int second) | |
| { | |
| this.year = year; | |
| this.month = month; | |
| this.day = day; | |
| this.hour = hour; | |
| this.minute = minute; | |
| this.second = second; | |
| } | |
| public double getJulianDay() | |
| { | |
| boolean julian = true; | |
| if (year < 1582 || (year == 1582 && month <= 10) || (year == 1582 && month == 10 && day < 15)) julian = false; | |
| int D = day; | |
| int M = month; | |
| int Y = year; | |
| if (M < 3) | |
| { | |
| Y--; | |
| M += 12; | |
| } | |
| int A = Y / 100; | |
| int B = julian ? 2 - A + A / 4 : 0; | |
| int C = Y < 0 ? (int)((365.25 * Y) - 0.75) : (int)(365.25 * Y); | |
| int F = (int)(30.6001 * (M + 1)); | |
| double dayFraction = (hour + (minute + (second / 60.0)) / 60.0) / 24.0; | |
| double jd = B + C + F + D + dayFraction + 1720994.5; | |
| return jd; | |
| } | |
| } |
by Untuk testing code diatas bisa menggunakan java compiler dan executor disini https://www.compilejava.net/
