diff options
Diffstat (limited to 'org')
| -rw-r--r-- | org/madore/ephem/Time.java | 50 |
1 files changed, 45 insertions, 5 deletions
diff --git a/org/madore/ephem/Time.java b/org/madore/ephem/Time.java index 3d2cb3e..b5af9c4 100644 --- a/org/madore/ephem/Time.java +++ b/org/madore/ephem/Time.java @@ -2,8 +2,11 @@ package org.madore.ephem; public final class Time { - public static final class LeapSecond { + public static abstract class UtcRegion { public int mjd; + } + + public static final class LeapSecond extends UtcRegion { public int offset; public LeapSecond(int mjd, int offset) { this.mjd = mjd; @@ -11,7 +14,33 @@ public final class Time { } } - public static final LeapSecond[] leapSecondsTable = new LeapSecond[] { + public static final class RubberSecond extends UtcRegion { + public double offset0; + public int mjd0; + public double scale0; + public RubberSecond(int mjd, double offset0, int mjd0, double scale0) { + this.mjd = mjd; + this.offset0 = offset0; + this.mjd0 = mjd0; + this.scale0 = scale0; + } + } + + public static final UtcRegion[] leapSecondsTable = new UtcRegion[] { + // From <URL: http://maia.usno.navy.mil/ser7/tai-utc.dat > + new RubberSecond(37300, 1.4228180, 37300, 0.001296 ), + new RubberSecond(37512, 1.3728180, 37300, 0.001296 ), + new RubberSecond(37665, 1.8458580, 37665, 0.0011232), + new RubberSecond(38334, 1.9458580, 37665, 0.0011232), + new RubberSecond(38395, 3.2401300, 38761, 0.001296 ), + new RubberSecond(38486, 3.3401300, 38761, 0.001296 ), + new RubberSecond(38639, 3.4401300, 38761, 0.001296 ), + new RubberSecond(38761, 3.5401300, 38761, 0.001296 ), + new RubberSecond(38820, 3.6401300, 38761, 0.001296 ), + new RubberSecond(38942, 3.7401300, 38761, 0.001296 ), + new RubberSecond(39004, 3.8401300, 38761, 0.001296 ), + new RubberSecond(39126, 4.3131700, 39126, 0.002592 ), + new RubberSecond(39887, 4.2131700, 39126, 0.002592 ), new LeapSecond(41317, 10), new LeapSecond(41499, 11), new LeapSecond(41683, 12), @@ -40,8 +69,8 @@ public final class Time { new LeapSecond(56109, 35), }; - public static double utcToTt(int utcMjd, double utcSeconds) { - // Returns JD in TT + public static double utcOffset(int utcMjd, double utcSeconds) { + // Returns TAI-UTC in seconds int i0 = 0; int i1 = leapSecondsTable.length; while ( i1-i0 > 1 ) { int i = (i0+i1)/2; @@ -50,7 +79,18 @@ public final class Time { else i1 = i; } - return ( utcSeconds + leapSecondsTable[i0].offset + 32.184 )/86400. + utcMjd + 2400000.5; + double utcOffset; + if ( leapSecondsTable[i0] instanceof LeapSecond ) + utcOffset = ((LeapSecond)leapSecondsTable[i0]).offset; + else + utcOffset = ((RubberSecond)leapSecondsTable[i0]).offset0 + + (utcMjd - ((RubberSecond)leapSecondsTable[i0]).mjd0) * ((RubberSecond)leapSecondsTable[i0]).scale0; + return utcOffset; + } + + public static double utcToTt(int utcMjd, double utcSeconds) { + // Returns JD in TT + return ( utcSeconds + utcOffset(utcMjd, utcSeconds) + 32.184 )/86400. + utcMjd + 2400000.5; } } |