astro_calendar.py

# esempio: come usare questa classe in una funzione esterna
# from calendar import sun
# s = sun()
# oppore s = (latitudine,longitudine)
# alba = s.sunrise()                                    restituisce oggetto time
# tramonto = s.sunset()                                 restituisce oggetto time
# zenith = s.solarnoon()                                restituisce oggetto time
# local_time = datetime.datetime.now()                  restituisce oggetto datatime
# utc_time = datetime.datetime.utcnow()                 restituisce oggetto datatime
# oppure utc_time = s. timeutc()                        restituisce oggetto datatime

from math import cos,sin,acos,asin,tan
from math import degrees as deg, radians as rad
from datetime import date,datetime,time
import datetime
import urllib2
import string

class sun:
        def __init__(self,lat=43.252,long=13.5097): # default Corridonia
                # __init__      Costruttore di oggetto
                self.lat=lat
                self.long=long

        # MIA FUNZIONE: data e ora UTC presa da internet
        # esempio chiamata alla funzione self.timeutc()
        def timeutc(self):
                nomefile = "http://just-the-time.appspot.com/"
                line = urllib2.urlopen(nomefile).read()
                line = line[:-1]
                [data,ora,description] = string.split(line," ") # separo le variabili
                [anno,mese,giorno] = string.split(data,"-")
                [ore,minuti,secondi] = string.split(ora,":")
                millisecondi = 0
                return datetime.datetime(int(anno),int(mese),int(giorno),int(ore),int(minuti),int(secondi),millisecondi)

        # alba
        def sunrise(self,when=None):
#               if when is None : when = datetime.datetime.now()
#               datetime.datetime.now() mi restituisce data eora attuale
#               datetime.datetime.utcnow() mi restituisce data e ora UTC (di Greenwich)
                if when is None : when = datetime.datetime.utcnow()
                self.__preptime(when)
                self.__calc()
                return sun.__timefromdecimalday(self.sunrise_t)

        # tramonto
        def sunset(self,when=None):
                if when is None : when = datetime.datetime.utcnow()
                self.__preptime(when)
                self.__calc()
                return sun.__timefromdecimalday(self.sunset_t)

        # mezzogiorno solare
        def solarnoon(self,when=None):
                if when is None : when = datetime.datetime.utcnow()
                self.__preptime(when)
                self.__calc()
                return sun.__timefromdecimalday(self.solarnoon_t)

        @staticmethod
        def __timefromdecimalday(day):
                # day formatta i tre valori di self.solarnoon_t self.sunrise_t self.sunset_t
                hours  = 24.0*day
                h      = int(hours)
                minutes= (hours-h)*60
                m      = int(minutes)
                seconds= (minutes-m)*60
                s      = int(seconds)
                return time(hour=h,minute=m,second=s)

        def __preptime(self,when):
                # datetime days are numbered in the Gregorian calendar
                # while the calculations from NOAA are distibuted as
                # OpenOffice spreadsheets with days numbered from
                # 1/1/1900. The difference are those numbers taken for
                # 18/12/2010
                self.day = when.toordinal()-(734124-40529) # la data attuale in giorni dai primi del 1900
                t=when.time() # t a come valore l'ora attuale
                self.time= (t.hour + t.minute/60.0 + t.second/3600.0)/24.0
# timezone ora solare +1 ora legale +2
#               imposto timezone a 0 cosi ottengo ora UTC rispetto a Greenwich
                self.timezone=0
                offset=when.utcoffset() # offset vale None
                if not offset is None:
                        self.timezone=offset.seconds/3600.0

    def __calc(self):
            timezone = self.timezone # in hours, east is positive
                longitude= self.long     # in decimal degrees, east is positive
                latitude = self.lat      # in decimal degrees, north is positive

                time  = self.time # percentage past midnight, i.e. noon  is 0.5
                day      = self.day     # daynumber 1=1/1/1900

                Jday     =day+2415018.5+time-timezone/24 # Julian day
                Jcent    =(Jday-2451545)/36525    # Julian century

                Manom    = 357.52911+Jcent*(35999.05029-0.0001537*Jcent)
                Mlong    = 280.46646+Jcent*(36000.76983+Jcent*0.0003032)%360
                Eccent   = 0.016708634-Jcent*(0.000042037+0.0001537*Jcent)
                Mobliq   = 23+(26+((21.448-Jcent*(46.815+Jcent*(0.00059-Jcent*0.001813))))/60)/60
                obliq    = Mobliq+0.00256*cos(rad(125.04-1934.136*Jcent))
                vary     = tan(rad(obliq/2))*tan(rad(obliq/2))
                Seqcent  = sin(rad(Manom))*(1.914602-Jcent*(0.004817+0.000014*Jcent))+sin(rad(2*Manom))*(0.019993-0.000101*Jcent)+sin(rad(3*Manom))*0.000289

                Struelong= Mlong+Seqcent
                Sapplong = Struelong-0.00569-0.00478*sin(rad(125.04-1934.136*Jcent))
                declination = deg(asin(sin(rad(obliq))*sin(rad(Sapplong))))

                eqtime   = 4*deg(vary*sin(2*rad(Mlong))-2*Eccent*sin(rad(Manom))+4*Eccent*vary*sin(rad(Manom))*cos(2*rad(Mlong))-0.5*vary*vary*sin(4*rad(Mlong))-1.25*Eccent*Eccent*sin(2*rad(Manom)))

                hourangle= deg(acos(cos(rad(90.833))/(cos(rad(latitude))*cos(rad(declination)))-tan(rad(latitude))*tan(rad(declination))))

                self.solarnoon_t=(720-4*longitude-eqtime+timezone*60)/1440
                self.sunrise_t  =self.solarnoon_t-hourangle*4/1440
                self.sunset_t   =self.solarnoon_t+hourangle*4/1440