//Julianische Tageszahl JD

if (mon <= 2) {
    this->Y = this->jahr - 1;
    this->M = this->mon + 12;
    //Tagesbruch berechnen + Tag
    this->tagbruch = this->std / 24 + this->minuten / 1440;
    this->D = this->tagbruch + this->tag;
}

if (mon > 2) {
    this->Y = this->jahr;
    this->M = this->mon;
    //Tagesbruch berechnen + Tag
    this->tagbruch = this->std / 24 + this->minuten / 1440;
    this->D = this->tagbruch + this->tag;
}
this->B = 0; //julianischer Kalender 
this->JD = (365.25 * (Y + 4716)) + (30.6001 * (M + 1)) + this->D + this->B - 1524.5;
this->n = this->JD - 2451545.0;