Initial commit

tools/julian.py

@@ -0,0 +1,58 @@
+# tools/julian.py
+
+from datetime import datetime, timedelta
+import math
+
+
+def julian_date(date: datetime | None = None):
+    """Given any date in the future or past, return julian date"""
+    if date is None:
+        date = datetime.now()
+
+    time = date.timestamp() * 1000
+
+    offset = date.utcoffset()
+    tzoffset = offset.total_seconds() // 60 if offset is not None else 0
+
+    return (time / 86400000) - (tzoffset / 1440) + 2440587.5
+
+
+def CJDN(date: datetime | None = None):
+    return round(julian_date(date))
+
+
+def current_julian_date():
+    """Returns current julian date"""
+    return julian_date()
+
+
+def tomorrow_julian_date():
+    """returns tomorrow's julian date"""
+    date = datetime.now() + timedelta(days=1)
+    return julian_date(date)
+
+
+def future_julian_date(hoursadd=0, minutesadd=0, secondsadd=0):
+    """defaults to current if no specifications made. HOURS, MINUTES, AND SECONDS CANNOT BE NEGATIVE"""
+    date = datetime.now() + timedelta(
+        hours=hoursadd, minutes=minutesadd, seconds=secondsadd
+    )
+    return julian_date(date)
+
+
+def epoch_days(date: datetime | None = None):
+    """returns days since Jan 1st, 2000. Negative if before this date"""
+    return julian_date(date) - 2451545
+
+
+def day_percent(date: datetime | None = None):
+    """Returns decimal portion of Julian Date"""
+    whole = julian_date(date)
+    return whole - math.floor(whole)
+
+
+def from_julian(j):
+    """Returns datetime.datetime object given julian date J"""
+    J1970 = 2440588
+    dayMs = 24 * 60 * 60 * 1000
+    return datetime.fromtimestamp((j + 0.5 - J1970) * dayMs / 1000.0)