//***************************************************
//the following scripts are used by andi boesch 2008
//as basic algorithms in the astro tools:
//http://www.cybervisuals.ch/astro
//***************************************************
//
//the functions are originaly written in javascript
//they are used by cybervisuals without any changes as actionscript in flash
//for function declaration javasrcipt and actionscript use the same syntax
//
//following functions are published by ole nielsen under the GNU GPL.
//http://www.ngc7000.org
//
//***************************************************
//part 1
//
// Copyright Ole Nielsen 2002-2003, Peter Hayes 1999-2001
//
//
function sunxyz(jday) {
	// return x,y,z ecliptic coordinates, distance, true longitude
	// days counted from 1999 Dec 31.0 UT
	var d = jday-2451543.5;
	var w = 282.9404+4.70935E-5*d;
	// argument of perihelion
	var e = 0.016709-1.151E-9*d;
	var M = rev(356.0470+0.9856002585*d);
	// mean anomaly
	var E = M+e*RAD2DEG*sind(M)*(1.0+e*cosd(M));
	var xv = cosd(E)-e;
	var yv = Math.sqrt(1.0-e*e)*sind(E);
	var v = atan2d(yv, xv);
	// true anomaly
	var r = Math.sqrt(xv*xv+yv*yv);
	// distance
	var lonsun = rev(v+w);
	// true longitude
	var xs = r*cosd(lonsun);
	// rectangular coordinates, zs = 0 for sun 
	var ys = r*sind(lonsun);
	return new Array(xs, ys, 0, r, lonsun, 0);
}
function SunAlt(jday, obs) {
	// return alt, az, time angle, ra, dec, ecl. long. and lat=0, illum=1, 0, dist, brightness 
	var sdat = sunxyz(jday);
	var ecl = 23.4393-3.563E-7*(jday-2451543.5);
	var xe = sdat[0];
	var ye = sdat[1]*cosd(ecl);
	var ze = sdat[1]*sind(ecl);
	var ra = rev(atan2d(ye, xe));
	var dec = atan2d(ze, Math.sqrt(xe*xe+ye*ye));
	var topo = radec2aa(ra, dec, jday, obs);
	return new Array(topo[0], topo[1], topo[2], ra, dec, sdat[4], 0, 1, 0, sdat[3], -26.74);
}
// Sun rise and set times (if twilight==-0.833) or desired twilight time. Return julian days
function sunrise(obs, twilight) {
	// obs is a reference variable make a copy
	var obscopy = new Object();
	for (var i in obs) {
		obscopy[i] = obs[i];
	}
	obscopy.hours = 12;
	obscopy.minutes = 0;
	obscopy.seconds = 0;
	var riseset = new Array(0.0, 0.0, false, 0.0, 0.0);
	var lst = local_sidereal(obscopy);
	var jday = jd(obscopy);
	var radec = SunAlt(jday, obscopy);
	var ra = radec[3];
	var dec = radec[4];
	var UTsun = 12.0+ra/15.0-lst;
	if (UTsun<0.0) {
		UTsun += 24.0;
	}
	if (UTsun>24.0) {
		UTsun -= 24.0;
	}
	var cosLHA = (sind(twilight)-sind(obs.latitude)*sind(dec))/(cosd(obs.latitude)*cosd(dec));
	// Check for midnight sun and midday night. "riseset[2]" false if no rise and set found
	riseset[2] = false;
	if (cosLHA<=1.0 && cosLHA>=-1.0) {
		// rise/set times allowing for not today.
		riseset[2] = true;
		var lha = acosd(cosLHA)/15.0;
		if ((UTsun-lha)<0.0) {
			var rtime = 24.0+UTsun-lha;
		} else {
			var rtime = UTsun-lha;
		}
		riseset[0] = jday+rtime/24.0-0.5;
		if ((UTsun+lha)>24.0) {
			var stime = UTsun+lha-24.0;
		} else {
			var stime = UTsun+lha;
			riseset[4] = stime;
		}
		riseset[1] = jday+stime/24.0-0.5;
		// riseset[3] and [4] are times in UT hours
		riseset[3] = rtime;
		riseset[4] = stime;
	}
	return (riseset);
}
function MoonPos(jday, obs) {
	// MoonPos calculates the Moon position and distance, based on Meeus chapter 47
	// and the illuminated percentage from Meeus equations 48.4 and 48.1
	// OPN: This version of MoonPos calculates the position to a precision of about 2' or so
	// All T^2, T^3 and T^4 terms skipped. NB: Time is not taken from obs but from jday (julian day)
	// Returns alt, az, hour angle, ra, dec (geocentr!), eclip. long and lat (geocentr!), 
	// illumination, distance, brightness and phase angle 
	var T = (jday-2451545.0)/36525;
	// Moons mean longitude L'
	var LP = rev(218.3164477+481267.88123421*T);
	// Moons mean elongation
	var D = rev(297.8501921+445267.1114034*T);
	// Suns mean anomaly
	var M = rev(357.5291092+35999.0502909*T);
	// Moons mean anomaly M'
	var MP = rev(134.9633964+477198.8675055*T);
	// Moons argument of latitude
	var F = rev(93.2720950+483202.0175233*T);
	// The "further arguments" A1, A2 and A3  and the term E have been ignored
	// Sum of most significant terms from table 45.A and 45.B (terms less than 0.004 deg / 40 km dropped)
	var Sl = 6288774*sind(MP)+1274027*sind(2*D-MP)+658314*sind(2*D)+213618*sind(2*MP)-185116*sind(M)-114332*sind(2*F)+58793*sind(2*D-2*MP)+57066*sind(2*D-M-MP)+53322*sind(2*D+MP)+45758*sind(2*D-M)-40923*sind(M-MP)-34720*sind(D)-30383*sind(M+MP)+15327*sind(2*D-2*F)-12528*sind(MP+2*F)+10980*sind(MP-2*F)+10675*sind(4*D-MP)+10034*sind(3*MP)+8548*sind(4*D-2*MP)-7888*sind(2*D+M-MP)-6766*sind(2*D+M)-5163*sind(D-MP)+4987*sind(D+M)+4036*sind(2*D-M+MP);
	var Sb = 5128122*sind(F)+280602*sind(MP+F)+277602*sind(MP-F)+173237*sind(2*D-F)+55413*sind(2*D-MP+F)+46271*sind(2*D-MP-F)+32573*sind(2*D+F)+17198*sind(2*MP+F)+9266*sind(2*D+MP-F)+8822*sind(2*MP-F)+8216*sind(2*D-M-F)+4324*sind(2*D-2*MP-F)+4200*sind(2*D+MP+F);
	var Sr = (-20905355)*cosd(MP)-3699111*cosd(2*D-MP)-2955968*cosd(2*D)-569925*cosd(2*MP)+246158*cosd(2*D-2*MP)-152138*cosd(2*D-M-MP)-170733*cosd(2*D+MP)-204586*cosd(2*D-M)-129620*cosd(M-MP)+108743*cosd(D)+104755*cosd(M+MP)+79661*cosd(MP-2*F)+48888*cosd(M);
	// geocentric longitude, latitude
	var mglong = rev(LP+Sl/1000000.0);
	var mglat = Sb/1000000.0;
	// Obliquity of Ecliptic
	var obl = 23.4393-3.563E-7*(jday-2451543.5);
	var ra = rev(atan2d(sind(mglong)*cosd(obl)-tand(mglat)*sind(obl), cosd(mglong)));
	var dec = asind(sind(mglat)*cosd(obl)+cosd(mglat)*sind(obl)*sind(mglong));
	var moondat = radec2aa(ra, dec, jday, obs);
	// phase angle (48.4)
	var pa = Math.abs(180.0-D-6.289*sind(MP)+2.100*sind(M)-1.274*sind(2*D-MP)-0.658*sind(2*D)-0.214*sind(2*MP)-0.11*sind(D));
	var k = (1+cosd(pa))/2;
	var mr = Math.round(385000.56+Sr/1000.0);
	var h = moondat[0];
	// correct for parallax, equatorial horizontal parallax, see Meeus p. 337
	h -= asind(6378.14/mr)*cosd(h);
	// brightness, use Paul Schlyter's formula (based on common phase law for Moon)
	var sdat = sunxyz(jday);
	var r = sdat[3];
	// Earth (= Moon) distance to Sun in AU
	var R = mr/149598000;
	// Moon distance to Earth in AU
	var mag = 0.23+5*log10(r*R)+0.026*pa+4.0E-9*pa*pa*pa*pa;
	return new Array(h, moondat[1], moondat[2], ra, dec, mglong, mglat, k, r, mr, mag);
}
// Moonpos()
function radec2aa(ra, dec, jday, obs) {
	// Convert ra/dec to alt/az, also return hour angle, azimut = 0 when north
	// DOES NOT correct for parallax!
	// TH0=Greenwich sid. time (eq. 12.4), H=hour angle (chapter 13)
	var TH0 = 280.46061837+360.98564736629*(jday-2451545.0);
	var H = rev(TH0-obs.longitude-ra);
	var alt = asind(sind(obs.latitude)*sind(dec)+cosd(obs.latitude)*cosd(dec)*cosd(H));
	var az = atan2d(sind(H), (cosd(H)*sind(obs.latitude)-tand(dec)*cosd(obs.latitude)));
	return new Array(alt, rev(az+180.0), H);
}
// radec2aa()
//
//
//***************************************************
//part 2
//
// Copyright Ole Nielsen 2002-2003, Peter Hayes 1999-2001
//
// The place, observatory definitions and daylight savings functions
function place(name, latitude, ns, longitude, we, zone, dss, dse) {
	this.name = name;
	this.latitude = latitude;
	this.ns = ns;
	this.longitude = longitude;
	this.we = we;
	this.zone = zone;
	this.dss = dss;
	this.dse = dse;
}
// A selection of places
// Please leave Greenwich in the first entry as the default
// The second entry is my home town, I suggest you change it to yours
// is you keep a copy for your personal use.
// This database is based on Peter Hayes' original database with several places added
var atlas = new Array(new place("UK:Greenwich", "51:28:38", 0, "00:00:00", 0, 0, "3:5:0", "10:5:0"), new place("NL:Rijswijk", "52:02:00", 0, "4:19:00", 1, -60, "3:5:0", "10:5:0"), new place("AT:Vienna", "48:13:00", 0, "16:22:00", 1, -60, "3:5:0", "10:5:0"), new place("AU:Melbourne", "37:48:00", 1, "144:58:00", 1, -600, "10:5:0", "03:5:0"), new place("AU:Perth", "31:58:00", 1, "115:49:00", 1, -480, "10:5:0", "03:5:0"), new place("BE:Brussels", "50:50:00", 0, "4:21:00", 1, -60, "3:5:0", "10:5:0"), new place("BR:Rio de Janeiro", "22:54:00", 1, "43:16:00", 0, 180, "", ""), new place("CA:Calgary", "51:03:00", 0, "114:05:00", 0, 420, "04:1:0", "10:5:0"), new place("CA:Halifax", "44:35:00", 0, "63:39:00", 0, 240, "04:1:0", "10:5:0"), new place("CA:Toronto", "43:39:00", 0, "79:23:00", 0, 300, "04:1:0", "10:5:0"), new place("CH:Zurich", "47:22:40", 0, "08:33:04", 1, -60, "3:5:0", "10:5:0"), new place("CL:Santiago", "33:30:00", 1, "70:40:00", 0, 240, "10:5:0", "03:5:0"), new place("DE:Berlin", "52:32:00", 0, "13:25:00", 1, -60, "3:5:0", "10:5:0"), new place("DE:Frankfurt/Main", "50:06:00", 0, "8:41:00", 1, -60, "3:5:0", "10:5:0"), new place("DE:Hamburg", "53:33:00", 0, "10:00:00", 1, -60, "3:5:0", "10:5:0"), new place("DE:Munich", "48:08:00", 0, "11:35:00", 1, -60, "3:5:0", "10:5:0"), new place("DK:Copenhagen", "55:43:00", 0, "12:34:00", 1, -60, "3:5:0", "10:5:0"), new place("DK:Kolding", "55:31:00", 0, "9:29:00", 1, -60, "3:5:0", "10:5:0"), new place("DK:Aalborg", "57:03:00", 0, "9:51:00", 1, -60, "3:5:0", "10:5:0"), new place("DK:Århus", "56:10:00", 0, "10:13:00", 1, -60, "3:5:0", "10:5:0"), new place("EG:Cairo", "30:03:00", 0, "31:15:00", 1, -120, "", ""), new place("ES:Madrid", "40:25:00", 0, "03:42:00", 0, -60, "3:5:0", "10:5:0"), new place("ES:Malaga", "36:43:00", 0, "04:25:00", 0, -60, "3:5:0", "10:5:0"), new place("ES:Las Palmas", "28:08:00", 0, "15:27:00", 0, 60, "3:5:0", "10:5:0"), new place("FI:Helsinki", "60:08:00", 0, "25:00:00", 1, -120, "3:5:0", "10:5:0"), new place("FR:Bordeaux", "44:50:00", 0, "0:34:00", 0, -60, "3:5:0", "10:5:0"), new place("FR:Brest", "48:24:00", 0, "4:30:00", 0, -60, "3:5:0", "10:5:0"), new place("FR:Lille", "50:38:00", 0, "03:04:00", 1, -60, "3:5:0", "10:5:0"), new place("FR:Lyon", "45:46:00", 0, "04:50:00", 1, -60, "3:5:0", "10:5:0"), new place("FR:Marseille", "43:18:00", 0, "5:22:00", 1, -60, "3:5:0", "10:5:0"), new place("FR:Paris", "48:48:00", 0, "02:14:00", 1, -60, "3:5:0", "10:5:0"), new place("FR:Puimichel", "43:58:00", 0, "06:01:00", 1, -60, "3:5:0", "10:5:0"), new place("FR:Strasbourg", "48:35:00", 0, "7:45:00", 1, -60, "3:5:0", "10:5:0"), new place("GL:Nuuk", "64:15:00", 0, "51:34:00", 0, 180, "3:5:0", "10:5:0"), new place("GR:Athens", "38:00:00", 0, "23:44:00", 1, -120, "3:5:0", "10:5:0"), new place("HK:Hong Kong", "22:15:00", 0, "114:11:00", 1, -480, "", ""), new place("HR:Zagreb", "45:48:00", 0, "15:58:00", 1, -60, "3:5:0", "10:5:0"), new place("IE:Dublin", "53:19:48", 0, "06:15:00", 0, 0, "3:5:0", "10:5:0"), new place("IN:New Delhi", "28:22:00", 0, "77:13:00", 1, -330, "", ""), new place("IQ:Baghdad", "33:20:00", 0, "44:26:00", 1, -180, "", ""), new place("IR:Teheran", "35:44:00", 0, "51:30:00", 1, -210, "", ""), new place("IS:Reykjavik", "64:09:00", 0, "21:58:00", 0, 60, "3:5:0", "10:5:0"), new place("IT:Milan", "45:28:00", 0, "9:12:00", 1, -60, "3:5:0", "10:5:0"), new place("IT:Palermo", "38:08:00", 0, "13:23:00", 1, -60, "3:5:0", "10:5:0"), new place("IT:Rome", "41:53:00", 0, "12:30:00", 1, -60, "3:5:0", "10:5:0"), new place("JP:Tokyo", "35:70:00", 0, "139:46:00", 1, -540, "3:5:0", "10:5:0"), new place("LU:Luxembourg", "49:36:00", 0, "6:09:00", 1, -60, "3:5:0", "10:5:0"), new place("NL:Amsterdam", "52:22:23", 0, "4:53:33", 1, -60, "3:5:0", "10:5:0"), new place("NL:Apeldoorn", "52:13:00", 0, "5:57:00", 1, -60, "3:5:0", "10:5:0"), new place("NL:Maastricht", "50:51:00", 0, "5:04:00", 1, -60, "3:5:0", "10:5:0"), new place("NL:Groningen", "53:13:00", 0, "6:33:00", 1, -60, "3:5:0", "10:5:0"), new place("NL:The Hague", "52:05:00", 0, "4:29:00", 1, -60, "3:5:0", "10:5:0"), new place("NL:Utrecht", "52:05:10", 0, "05:07:45", 1, -60, "3:5:0", "10:5:0"), new place("NO:Bergen", "60:21:00", 0, "5:20:00", 1, -60, "3:5:0", "10:5:0"), new place("NO:Oslo", "59:56:00", 0, "10:45:00", 1, -60, "3:5:0", "10:5:0"), new place("NO:Tromsø", "69:70:00", 0, "19:00:00", 1, -60, "3:5:0", "10:5:0"), new place("NZ:Wellington", "41:17:00", 1, "174:47:00", 1, -720, "10:5:0", "03:5:0"), new place("PL:Warszawa", "52:15:00", 0, "21:00:00", 1, -60, "3:5:0", "10:5:0"), new place("PT:Faro", "37:01:00", 0, "7:56:00", 0, 0, "3:5:0", "10:5:0"), new place("PT:Lisbon", "38:44:00", 0, "9:08:00", 0, 0, "3:5:0", "10:5:0"), new place("PR:San Juan", "18:28:00", 0, "66:08:00", 0, 240, "04:1:0", "10:5:0"), new place("RO:Bucharest", "44:25:00", 0, "26:07:00", 1, -120, "3:5:0", "10:5:0"), new place("RU:Irkutsk", "52:18:00", 0, "104:15:00", 1, -480, "3:5:0", "10:5:0"), new place("RU:Moscow", "55:45:00", 0, "37:35:00", 1, -180, "3:5:0", "10:5:0"), new place("RU:Omsk", "55:00:00", 0, "73:22:00", 1, -360, "3:5:0", "10:5:0"), new place("SE:Gothenburg", "57:43:00", 0, "11:58:00", 1, -60, "3:5:0", "10:5:0"), new place("SE:Stockholm", "59:35:00", 0, "18:06:00", 1, -60, "3:5:0", "10:5:0"), new place("SE:Luleå", "65:35:00", 0, "22:09:00", 1, -60, "3:5:0", "10:5:0"), new place("SG:Singapore", "01:20:00", 0, "103:50:00", 1, -450, "", ""), new place("VC:Kingstown", "13:15:00", 0, "61:12:00", 0, 240, "", ""), new place("UK:Birmingham", "52:30:00", 0, "01:49:48", 0, 0, "3:5:0", "10:5:0"), new place("UK:Belfast", "54:34:48", 0, "05:55:12", 0, 0, "3:5:0", "10:5:0"), new place("UK:Cambridge", "52:10:00", 0, "00:06:00", 0, 0, "3:5:0", "10:5:0"), new place("UK:Cardiff", "51:30:00", 0, "03:12:00", 0, 0, "3:5:0", "10:5:0"), new place("UK:Edinburgh", "55:55:48", 0, "03:13:48", 0, 0, "3:5:0", "10:5:0"), new place("UK:London", "51:30:00", 0, "00:10:12", 0, 0, "3:5:0", "10:5:0"), new place("US:Anchorage", "61:10:00", 0, "149:53:00", 0, 560, "04:1:0", "10:5:0"), new place("US:Dallas", "32:48:00", 0, "96:48:00", 0, 360, "04:1:0", "10:5:0"), new place("US:Denver", "39:45:00", 0, "104:59:00", 0, 420, "04:1:0", "10:5:0"), new place("US:Honolulu", "21:19:00", 0, "157:86:00", 0, 600, "04:1:0", "10:5:0"), new place("US:Los Angeles", "34:03:15", 0, "118:14:28", 0, 480, "04:1:0", "10:5:0"), new place("US:Miami", "25:47:00", 0, "80:20:00", 0, 300, "04:1:0", "10:5:0"), new place("US:Minneapolis", "44:58:01", 0, "93:15:00", 0, 360, "04:1:0", "10:5:0"), new place("US:Seattle", "47:36:00", 0, "122:19:00", 0, 480, "04:1:0", "10:5:0"), new place("US:Washington DC", "38:53:51", 0, "77:00:33", 0, 300, "04:1:0", "10:5:0"), new place("VC:St Vincent", "13:15:00", 0, "61:12:00", 0, 240, "", ""), new place("ZA:Cape Town", "33:56:00", 1, "18:28:00", 1, -120, "", ""), new place("ZM:Lusaka", "15:26:00", 1, "28:20:00", 1, -120, "", ""));
//
function observatory(place, year, month, day, hr, min, sec) {
	// The observatory object holds local date and time,
	// timezone correction in minutes with daylight saving if applicable,
	// latitude and longitude (west is positive)
	this.name = place.name;
	this.year = year;
	this.month = month;
	this.day = day;
	this.hours = hr;
	this.minutes = min;
	this.seconds = sec;
	this.tz = place.tz;
	this.dst = false;
	// is it DST?
	this.latitude = place.latitude;
	this.longitude = place.longitude;
}
// The default observatory (Greenwich noon Jan 1 2000) 
// changed by user setting place and time from menu
var observer = new observatory(atlas[0], 2000, 1, 1, 12, 0, 0);
// Site name returns name and latitude / longitude as a string
function sitename() {
	var sname = observer.name;
	var latd = Math.abs(observer.latitude)+0.00001;
	var latdi = Math.floor(latd);
	sname += ((latdi<10) ? " 0" : " ")+latdi;
	latm = 60*(latd-latdi);
	latmi = Math.floor(latm);
	sname += ((latmi<10) ? ":0" : ":")+latmi;
	//  lats=60*(latm-latmi); latsi=Math.floor(lats);
	//  sname+=((latsi < 10) ? ":0" : ":") + latsi;
	sname += ((observer.latitude>=0) ? " N, " : " S, ");
	var longd = Math.abs(observer.longitude)+0.00001;
	var longdi = Math.floor(longd);
	sname += ((longdi<10) ? "0" : "")+longdi;
	longm = 60*(longd-longdi);
	longmi = Math.floor(longm);
	sname += ((longmi<10) ? ":0" : ":")+longmi;
	//  longs=60*(longm-longmi); longsi=Math.floor(longs);
	//  sname+=((longsi < 10) ? ":0" : ":") + longsi;
	sname += ((observer.longitude>=0) ? " W" : " E");
	return sname;
}
// sitename()
function checkdst(obs) {
	// Check DST is an attempt to check daylight saving, its not perfect.
	// Returns 0 or -60 that is amount to remove to get to zone time.
	// this function is now only called when selecting a place from the dropdown list. No dst check when updating the time!
	// We only know daylight saving if in the atlas
	if ((tbl.Place.selectedIndex<0) || (tbl.Place.selectedIndex>=atlas.length)) {
		return 0;
	}
	var dss = atlas[tbl.Place.selectedIndex].dss;
	var dse = atlas[tbl.Place.selectedIndex].dse;
	var ns = atlas[tbl.Place.selectedIndex].ns;
	if (dss.length == 0) {
		return 0;
	}
	if (dse.length == 0) {
		return 0;
	}
	// parse the daylight saving start & end dates
	var col1 = dss.indexOf(":");
	var col2 = dss.lastIndexOf(":");
	var col3 = dss.length;
	var dssm = parseInt(dss.substring(0, col1), 10);
	var dssw = parseInt(dss.substring(col1+1, col2), 10);
	var dssd = parseInt(dss.substring(col2+1, col3), 10);
	col1 = dse.indexOf(":");
	col2 = dse.lastIndexOf(":");
	col3 = dse.length;
	var dsem = parseInt(dse.substring(0, col1), 10);
	var dsew = parseInt(dse.substring(col1+1, col2), 10);
	var dsed = parseInt(dse.substring(col2+1, col3), 10);
	// Length of months
	// year,month,day and day of week
	var jdt = jd0(obs.year, obs.month, obs.day);
	var ymd = jdtocd(jdt);
	// first day of month - we need to know day of week
	var fymd = jdtocd(jdt-ymd[2]+1);
	// look for daylight saving / summertime changes
	// first the simple month checks
	// Test for the northern hemisphere
	if (ns == 0) {
		if ((ymd[1]>dssm) && (ymd[1]<dsem)) {
			return -60;
		}
		if ((ymd[1]<dssm) || (ymd[1]>dsem)) {
			return 0;
		}
	} else {
		// Southern hemisphere, New years day is summer.
		if ((ymd[1]>dssm) || (ymd[1]<dsem)) {
			return -60;
		}
		if ((ymd[1]<dssm) && (ymd[1]>dsem)) {
			return 0;
		}
	}
	// check if we are in month of change over
	if (ymd[1] == dssm) {
		// month of start of summer time
		// date of change over
		var ddd = dssd-fymd[3]+1;
		ddd = ddd+7*dssw;
		while (ddd>month_length[ymd[1]-1]) {
			ddd -= 7;
		}
		if (ymd[2]<ddd) {
			return 0;
		}
		// assume its past the change time, its impossible
		// to know if the change has occured.
		return -60;
	}
	if (ymd[1] == dsem) {
		// month of end of summer time
		// date of change over
		var ddd = dsed-fymd[3]+1;
		ddd = ddd+7*dsew;
		while (ddd>month_length[ymd[1]-1]) {
			ddd -= 7;
		}
		if (ymd[2]<ddd) {
			return -60;
		}
		// see comment above for start time
		return 0;
	}
	return 0;
}
// checkdst()
function jd(obs) {
	// The Julian date at observer time
	var j = jd0(obs.year, obs.month, obs.day);
	j += (obs.hours+((obs.minutes+obs.tz)/60.0)+(obs.seconds/3600.0))/24;
	return j;
}
// jd()
function local_sidereal(obs) {
	// sidereal time in hours for observer
	var res = g_sidereal(obs.year, obs.month, obs.day);
	res += 1.00273790935*(obs.hours+(obs.minutes+obs.tz+(obs.seconds/60.0))/60.0);
	res -= obs.longitude/15.0;
	while (res<0) {
		res += 24.0;
	}
	while (res>24) {
		res -= 24.0;
	}
	return res;
}
//
//
//***************************************************
//part 3
//
// Various date and time functions
// Copyright Peter Hayes 1999-2001, Ole Nielsen 2002-2004
// must be updated using leapyear() if year changed
var month_length = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);
var dow = ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"];
function leapyear(year) {
	var leap = false;
	if (year%4 == 0) {
		leap = true;
	}
	if (year%100 == 0) {
		leap = false;
	}
	if (year%400 == 0) {
		leap = true;
	}
	return leap;
}
function jd0(year, month, day) {
	// The Julian date at 0 hours(*) UT at Greenwich
	// (*) or actual UT time if day comprises time as fraction
	var y = year;
	var m = month;
	if (m<3) {
		m += 12;
		y -= 1;
	}
	var a = Math.floor(y/100);
	var b = 2-a+Math.floor(a/4);
	var j = Math.floor(365.25*(y+4716))+Math.floor(30.6001*(m+1))+day+b-1524.5;
	return j;
}
// jd0()
function jdtocd(jd) {
	// The calendar date from julian date, see Meeus p. 63
	// Returns year, month, day, day of week, hours, minutes, seconds
	var Z = Math.floor(jd+0.5);
	var F = jd+0.5-Z;
	if (Z<2299161) {
		var A = Z;
	} else {
		var alpha = Math.floor((Z-1867216.25)/36524.25);
		var A = Z+1+alpha-Math.floor(alpha/4);
	}
	var B = A+1524;
	var C = Math.floor((B-122.1)/365.25);
	var D = Math.floor(365.25*C);
	var E = Math.floor((B-D)/30.6001);
	var d = B-D-Math.floor(30.6001*E)+F;
	if (E<14) {
		var month = E-1;
	} else {
		var month = E-13;
	}
	if (month>2) {
		var year = C-4716;
	} else {
		var year = C-4715;
	}
	var day = Math.floor(d);
	var h = (d-day)*24;
	var hours = Math.floor(h);
	var m = (h-hours)*60;
	var minutes = Math.floor(m);
	var seconds = Math.round((m-minutes)*60);
	if (seconds>=60) {
		minutes = minutes+1;
		seconds = seconds-60;
	}
	if (minutes>=60) {
		hours = hours+1;
		minutes = 0;
	}
	var dw = Math.floor(jd+1.5)-7*Math.floor((jd+1.5)/7);
	return new Array(year, month, day, dw, hours, minutes, seconds);
}
// jdtocd()
function g_sidereal(year, month, day) {
	// sidereal time in hours for Greenwich
	var T = (jd0(year, month, day)-2451545.0)/36525;
	var res = 100.46061837+T*(36000.770053608+T*(0.000387933-T/38710000.0));
	return rev(res)/15.0;
}
//
//
//***************************************************
//part 4
//
// Utility functions
// Copyright Ole Nielsen 2002-2004, Peter Hayes 1999-2001
function datestring(obs) {
	// datestring provides a locale independent format
	var datestr = "";
	datestr += obs.year;
	datestr += ((obs.month<10) ? ":0" : ":")+obs.month;
	datestr += ((obs.day<10) ? ":0" : ":")+obs.day;
	return datestr;
}
// end datestring()
function datestring2(year, month, day) {
	var datestr = "";
	datestr += year;
	datestr += ((month<10) ? ":0" : ":")+month;
	datestr += ((day<10) ? ":0" : ":")+day;
	return datestr;
}
// end datestring2()
function adjustTime(obs, amount) {
	// update date and time, amount is in minutes (may be negative)
	// added 2004
	month_length[1] = leapyear(obs.year) ? 29 : 28;
	if (amount<0) {
		amount = Math.abs(amount);
		obs.minutes -= amount%60;
		amount = Math.floor(amount/60.0);
		obs.hours -= amount%24;
		amount = Math.floor(amount/24.0);
		obs.day -= amount;
		if (obs.minutes<0) {
			obs.minutes += 60;
			obs.hours -= 1;
		}
		if (obs.hours<0) {
			obs.hours += 24;
			obs.day -= 1;
		}
		while (obs.day<1) {
			obs.day += month_length[obs.month-2+(obs.month == 1 ? 12 : 0)];
			obs.month -= 1;
			if (obs.month == 0) {
				obs.year -= 1;
				obs.month = 12;
				month_length[1] = (leapyear(obs.year) ? 29 : 28);
			}
		}
	} else {
		obs.minutes += amount%60;
		amount = Math.floor(amount/60.0);
		obs.hours += amount%24;
		amount = Math.floor(amount/24.0);
		obs.day += amount;
		if (obs.minutes>59) {
			obs.minutes -= 60;
			obs.hours += 1;
		}
		if (obs.hours>23) {
			obs.hours -= 24;
			obs.day += 1;
		}
		while (obs.day>month_length[obs.month-1]) {
			obs.day -= month_length[obs.month-1];
			obs.month += 1;
			if (obs.month == 13) {
				obs.year += 1;
				obs.month = 1;
				month_length[1] = (leapyear(obs.year) ? 29 : 28);
			}
		}
	}
}
// end adjustTime()
function hmsstring(t) {
	// the caller must add a leading + if required.
	var hours = Math.abs(t);
	var minutes = 60.0*(hours-Math.floor(hours));
	hours = Math.floor(hours);
	var seconds = Math.round(60.0*(minutes-Math.floor(minutes)));
	minutes = Math.floor(minutes);
	if (seconds>=60) {
		minutes += 1;
		seconds -= 60;
	}
	if (minutes>=60) {
		hour += 1;
		minutes -= 60;
	}
	if (hours>=24) {
		hours -= 24;
	}
	var hmsstr = (t<0) ? "-" : "";
	hmsstr = ((hours<10) ? "0" : "")+hours;
	hmsstr += ((minutes<10) ? ":0" : ":")+minutes;
	hmsstr += ((seconds<10) ? ":0" : ":")+seconds;
	return hmsstr;
}
// end hmsstring()
function hmstring(t, plus) {
	// hmstring converts hours to a string (+/-)hours:minutes, used for relative time (TZ)
	var hours = Math.abs(t);
	var minutes = Math.round(60.0*(hours-Math.floor(hours)));
	hours = Math.floor(hours);
	if (minutes>=60) {
		hours += 1;
		minutes -= 60;
	}
	// minutes could be 60 due to rounding
	if (hours>=24) {
		hours -= 24;
	}
	var hmstr = (t<0) ? "-" : (plus ? "+" : "");
	hmstr += ((hours<10) ? "0" : "")+hours;
	hmstr += ((minutes<10) ? ":0" : ":")+minutes;
	return hmstr;
}
// end hmstring()
function hmstring2(hours, minutes, seconds) {
	// hmstring2 returns time as a string HH:MM (added 2004.01.02), seconds needed for rounding
	if (seconds>=30) {
		minutes++;
	}
	if (minutes>=60) {
		hours++;
		minutes = 0;
	}
	var timestr = ((hours<10) ? "0" : "")+hours;
	timestr += ((minutes<10) ? ":0" : ":")+minutes;
	return timestr;
}
// end hmstring2()
function dmsstring(d) {
	// dmsstring converts lat/long angle to unsigned string d:m:s
	var deg = Math.abs(d);
	var minutes = 60.0*(deg-Math.floor(deg));
	deg = Math.floor(deg);
	var seconds = Math.round(60.0*(minutes-Math.floor(minutes)));
	minutes = Math.floor(minutes);
	if (seconds>=60) {
		minutes += 1;
		seconds -= 60;
	}
	if (minutes>=60) {
		deg += 1;
		minutes -= 60;
	}
	hmsstr = ((deg<10) ? "0" : "")+deg;
	hmsstr += ((minutes<10) ? ":0" : ":")+minutes;
	hmsstr += ((seconds<10) ? ":0" : ":")+seconds;
	return hmsstr;
}
// end dmsstring()
function dmstring(d) {
	// dmstring converts lat/long angle to unsigned string d:m
	var deg = Math.abs(d);
	var minutes = 60.0*(deg-Math.floor(deg));
	deg = Math.floor(deg);
	var seconds = Math.round(60.0*(minutes-Math.floor(minutes)));
	minutes = Math.floor(minutes);
	if (seconds>=30) {
		minutes += 1;
	}
	if (minutes>=60) {
		deg += 1;
		minutes -= 60;
	}
	hmstr = ((deg<10) ? "0" : "")+deg;
	hmstr += ((minutes<10) ? ":0" : ":")+minutes;
	return hmstr;
}
// end dmstring()
function anglestring(a, circle, arcmin) {
	// Return angle as degrees:minutes. 'circle' is true for range between 0 and 360 
	// and false for -90 to +90, if 'arcmin' use deg and arcmin symbols
	var ar = Math.round(a*60)/60;
	var deg = Math.abs(ar);
	var min = Math.round(60.0*(deg-Math.floor(deg)));
	if (min>=60) {
		deg += 1;
		min = 0;
	}
	var anglestr = "";
	if (!circle) {
		anglestr += (ar<0 ? "-" : "+");
	}
	if (circle) {
		anglestr += ((Math.floor(deg)<100) ? "0" : "");
	}
	anglestr += ((Math.floor(deg)<10) ? "0" : "")+Math.floor(deg);
	if (arcmin) {
		anglestr += ((min<10) ? "&deg;0" : "&deg;")+(min)+"' ";
	} else {
		anglestr += ((min<10) ? ":0" : ":")+(min);
	}
	return anglestr;
}
// end anglestring()
function fixnum(n, l, d) {
	// convert float n to right adjusted string of length l with d digits after decimal point.
	// the sign always requires one character, allow for that in l!
	var m = 1;
	for (var i = 0; i<d; i++) {
		m *= 10;
	}
	var n1 = Math.round(Math.abs(n)*m);
	var nint = Math.floor(n1/m);
	var nfract = (n1-m*nint)+"";
	// force conversion to string
	while (nfract.length<d) {
		nfract = "0"+nfract;
	}
	var str = (n<0 ? "-" : " ")+nint;
	if (d>0) {
		str = str+"."+nfract;
	}
	while (str.length<l) {
		str = " "+str;
	}
	return str;
}
// end fixnum()
function fixstr(str, l) {
	// returns left-adjusted string of length l, pad with spaces or truncate as necessary
	if (str.length>l) {
		return str.substring(0, l);
	}
	while (str.length<l) {
		str += " ";
	}
	return str;
}
// end fixstr()
function parsecol(str) {
	// parsecol converts deg:min:sec or hr:min:sec to a number
	var col1 = str.indexOf(":");
	var col2 = str.lastIndexOf(":");
	if (col1<0) {
		return parseInt(str);
	}
	if (str.substring(0, 1) == "-") {
		var res = parseInt(str.substring(1, col1), 10);
	} else {
		var res = parseInt(str.substring(0, col1), 10);
	}
	if (col2>col1) {
		res += (parseInt(str.substring(col1+1, col2), 10)/60.0)+(parseInt(str.substring(col2+1, str.length), 10)/3600.0);
	} else {
		res += (parseInt(str.substring(col1+1, str.length), 10)/60.0);
	}
	if (str.substring(0, 1) == "-") {
		return -res;
	} else {
		return res;
	}
}
// end parsecol()
function interpol(n, y1, y2, y3) {
	// interpolate y (Meeus 3.3)
	var a = y2-y1;
	var b = y3-y2;
	var c = b-a;
	return y2+(n/2)*(a+b+n*c);
}
function nzero(y1, y2, y3) {
	// Calculate value of interpolation factor for which y=zero. n0 should be within [-1:1] 
	// Meeus formula (3.7)	
	var a = y2-y1;
	var b = y3-y2;
	var c = b-a;
	var n0 = 0;
	do {
		dn0 = -(2*y2+n0*(a+b+c*n0))/(a+b+2*c*n0);
		n0 += dn0;
	} while (Math.abs(dn0)>0.0001);
	return n0;
}
// end nzero()
function nextrem(y1, y2, y3) {
	// Calculate value of interpolation factor for which y reaches extremum (-1<n<1);
	var a = y2-y1;
	var b = y3-y2;
	var c = b-a;
	var nm = -(a+b)/(2*c);
	// (3.5)
	return nm;
}
// end nextrem();
function isort(arr) {
	// Sort 2D array in ascending order on first column of each element using insertion sort 
	for (var c = 0; c<arr.length-1; c++) {
		var tmp = arr[c+1];
		var a = c;
		while (a>=0 && arr[a][0]>tmp[0]) {
			arr[a+1] = arr[a];
			a--;
		}
		arr[a+1] = tmp;
	}
}
// end isort()
//
//
//***************************************************
//part 5
//
// Extensions to the Math routines - Trig routines in degrees
// Copyright Peter Hayes 1999-2001, Ole Nielsen 2003-2004
var DEG2RAD = Math.PI/180.0;
var RAD2DEG = 180.0/Math.PI;
function rev(angle) {
	return angle-Math.floor(angle/360.0)*360.0;
}
// 0<=a<360
function rev2(angle) {
	var a = rev(angle);
	return (a>=180 ? a-360.0 : a);
}
// -180<=a<180
function sind(angle) {
	return Math.sin(angle*DEG2RAD);
}
function cosd(angle) {
	return Math.cos(angle*DEG2RAD);
}
function tand(angle) {
	return Math.tan(angle*DEG2RAD);
}
function asind(c) {
	return RAD2DEG*Math.asin(c);
}
function acosd(c) {
	return RAD2DEG*Math.acos(c);
}
function atand(c) {
	return RAD2DEG*Math.atan(c);
}
function atan2d(y, x) {
	return RAD2DEG*Math.atan2(y, x);
}
function log10(x) {
	return Math.LOG10E*Math.log(x);
}
function sqr(x) {
	return x*x;
}
function cbrt(x) {
	return Math.pow(x, 1/3.0);
}
function SGN(x) {
	return (x<0) ? -1 : +1;
}
//
//
//***************************************************
//part 6
//
// FUNCTIONS FOR FINDING EVENTS
//
// Copyright Ole Nielsen 2002-2004
// Please read copyright notice in astrotools2.html source
//
// 'Meeus' means "Astronomical Algorithms", 2nd ed. by Jean Meeus
// standard altitudes for rise and set
var H0SUN = -0.833;
var H0STAR = -0.583;
//
//
function findEvents(obj, jday, obs) {
	// Version 2
	// Calculate daily events (rise, transit, set etc) for one day starting at jday
	// Returns chronological sorted array of records, each record comprising time [0<=t<1] relative to jday
	// and event type. Event type codes are: 
	//	0: transit; -1/1: rise/set; -2/2: civ. twil. start/end; -3/3 naut twil; -4/4: astr twil
	// The first record is different: Type code is 0 for object up, 1 for less than 6 deg below horizon etc
	// The code is a little bit 'hairy'. Basically, it determines the nearest transit time of the 
	// object at each side of the middle of the time interval, and from these transit times it 
	// calculates rise and set times (and twilights for the Sun).
	//
	// reference horizon h0 for Moon depends on parallax, see Meeus p. 102
	if (obj == MOON) {
		bodies[obj].update(jday+0.5, obs);
		var par = asind(6378.14/bodies[obj].dist);
		var h0moon = 0.7275*par-0.567;
	}
	// rise/set altitude depends on object
	var href0 = ((obj == SUN) ? H0SUN : H0STAR);
	if (obj == MOON) {
		href0 = h0moon;
	}
	// stores the various events in records of [t, type]
	var events = new Array();
	var count = 0;
	// find situation at start of interval (not currently used by AstroTools but needed by Skyplanner)
	bodies[obj].update(jday, obs);
	var altaz = radec2aa(bodies[obj].ra, bodies[obj].dec, jday, obs);
	var alt = altaz[0];
	var type = 4;
	// object is visible
	if (alt>href0) {
		type = 0;
	} else if (alt>-6) {
		// civil twilight
		type = 1;
	} else if (alt>-12) {
		// naut. twil.
		type = 2;
	} else if (alt>-18) {
		// astr. twil.
		type = 3;
	}
	events[count++] = new Array(0, type);
	bodies[obj].update(jday+0.5, obs);
	var dec1 = bodies[obj].dec;
	var altaz = radec2aa(bodies[obj].ra, bodies[obj].dec, jday+0.5, obs);
	// H is hour angle
	var H = altaz[2];
	// first transit approx.
	var m = -H/360.0;
	// check for events around first and second transit
	for (var i = 0; i<2; i++) {
		bodies[obj].update(jday+0.5+m, obs);
		var altaz = radec2aa(bodies[obj].ra, bodies[obj].dec, jday+0.5+m, obs);
		var H = altaz[2]>180.0 ? altaz[2]-360 : altaz[2];
		// correction to transit time (Meeus page 103)
		m0 = m-H/360.0;
		if (m0>=-0.5 && m0<0.5) {
			// save transit time
			events[count++] = new Array(m0+0.5, 0);
		}
		// find rise and set times (and start/end of twilights if sun)
		for (var j = 0; j<=(obj == SUN ? 3 : 0); j++) {
			// href is the desired reference horizon
			var href = -6.0*j;
			if (href == 0.0) {
				href = href0;
			}
			// (Meeus 15.1)
			var cosH0 = (sind(href)-sind(obs.latitude)*sind(dec1))/(cosd(obs.latitude)*cosd(dec1));
			if (cosH0>=-1.0 && cosH0<=1.0) {
				// this may miss occasional rises/sets in polar regions, especially for Moon
				var H0 = acosd(cosH0);
				// rise (Meeus 15.2)
				var m1 = m0-H0/360.0;
				bodies[obj].update(jday+0.5+m1, obs);
				var altaz = radec2aa(bodies[obj].ra, bodies[obj].dec, jday+0.5+m1, obs);
				H = altaz[2];
				// correction to rise time
				m1 += (altaz[0]-href)/(360*cosd(bodies[obj].dec)*cosd(obs.latitude)*sind(H));
				// only keep event within interval of interest
				if (m1>=-0.5 && m1<0.5) {
					events[count++] = new Array(m1+0.5, -j-1);
				}
				// set
				var m2 = m0+H0/360.0;
				bodies[obj].update(jday+0.5+m2, obs);
				var altaz = radec2aa(bodies[obj].ra, bodies[obj].dec, jday+0.5+m2, obs);
				H = altaz[2];
				// correction to set time
				m2 += (altaz[0]-href)/(360*cosd(bodies[obj].dec)*cosd(obs.latitude)*sind(H));
				if (m2>=-0.5 && m2<0.5) {
					events[count++] = new Array(m2+0.5, j+1);
				}
			}
		}
		// second transit approx.
		m += 1.0;
	}
	// end marker
	events[count++] = new Array(1.0, -9);
	// bring in chronological order
	isort(events);
	return events;
}
// end findEvents()
//
//
//***************************************************
//part 7
//
// Functions for the planets
// Copyright Ole Nielsen 2002-2004
// Please read copyright notice in astrotools2.html source
// Formulae and elements from Paul Schlyter's article "Computing planetary positions" available at 
// http://hem.passagen.se/pausch/comp/ppcomp.html
MERCURY = 0;
VENUS = 1;
EARTH = 2;
MARS = 3;
JUPITER = 4;
SATURN = 5;
URANUS = 6;
NEPTUNE = 7;
SUN = 9;
MOON = 10;
COMET = 15;
USER = 20;
// Planet diameters at 1 AU in arcsec (km for Moon)
var ndiam = [6.72, 16.68, 1, 9.36, 196.88, 165.46, 70.04, 67.0, 1, 1919.3, 716900000.0];
// The planet object
function planet(name, num, N, i, w, a, e, M) {
	this.name = name;
	this.num = num;
	this.N = N;
	// longitude of ascending node
	this.i = i;
	// inclination
	this.w = w;
	// argument of perihelion
	this.a = a;
	// semimajor axis
	this.e = e;
	// eccentricity
	this.M = M;
	// mean anomaly
}
// elements from Paul Schlyter
var planets = new Array();
planets[0] = new planet("Mercury", 0, new Array(48.3313, 3.24587E-5), new Array(7.0047, 5.00E-8), new Array(29.1241, 1.01444E-5), new Array(0.387098, 0), new Array(0.205635, 5.59E-10), new Array(168.6562, 4.0923344368));
planets[1] = new planet("Venus  ", 1, new Array(76.6799, 2.46590E-5), new Array(3.3946, 2.75E-8), new Array(54.8910, 1.38374E-5), new Array(0.723330, 0), new Array(0.006773, -1.302E-9), new Array(48.0052, 1.6021302244));
planets[2] = new planet("Earth  ", 2, new Array(0, 0), new Array(0, 0), new Array(0, 0), new Array(0.0, 0.0), new Array(0.0, 0.0), new Array(0, 0));
planets[3] = new planet("Mars   ", 3, new Array(49.5574, 2.11081E-5), new Array(1.8497, -1.78E-8), new Array(286.5016, 2.92961E-5), new Array(1.523688, 0), new Array(0.093405, 2.516E-9), new Array(18.6021, 0.5240207766));
planets[4] = new planet("Jupiter", 4, new Array(100.4542, 2.76854E-5), new Array(1.3030, -1.557E-7), new Array(273.8777, 1.64505E-5), new Array(5.20256, 0), new Array(0.048498, 4.469E-9), new Array(19.8950, 0.0830853001));
planets[5] = new planet("Saturn ", 5, new Array(113.6634, 2.38980E-5), new Array(2.4886, -1.081E-7), new Array(339.3939, 2.97661E-5), new Array(9.55475, 0), new Array(0.055546, -9.499E-9), new Array(316.9670, 0.0334442282));
planets[6] = new planet("Uranus ", 6, new Array(74.0005, 1.3978E-5), new Array(0.7733, 1.9E-8), new Array(96.6612, 3.0565E-5), new Array(19.18171, -1.55E-8), new Array(0.047318, 7.45E-9), new Array(142.5905, 0.011725806));
planets[7] = new planet("Neptune", 7, new Array(131.7806, 3.0173E-5), new Array(1.7700, -2.55E-7), new Array(272.8461, -6.027E-6), new Array(30.05826, 3.313E-8), new Array(0.008606, 2.15E-9), new Array(260.2471, 0.005995147));
// Body holds current data of planet, Sun or Moon), method .update(jday,obs)
function Body(name, number, colour, colleft, colright) {
	this.name = name;
	this.number = number;
	this.colour = colour;
	this.colleft = colleft;
	this.colright = colright;
	this.alt = 0;
	this.az = 0;
	this.dec = 0;
	this.ra = 0;
	this.H = 0;
	this.eclon = 0;
	this.eclat = 0;
	this.illum = 1;
	this.r = 1;
	// heliocentric distance
	this.dist = 1;
	//geocentric distance
	this.mag = -1.0;
	this.elong = 0;
	this.pa = 0;
	// position angle (elongation)
	this.update = updatePosition;
	this.elongupdate = updateElong;
}
bodies = new Array();
bodies[0] = new Body("Mercury", MERCURY, 0, 24, 25);
bodies[1] = new Body("Venus  ", VENUS, 1, 24, 25);
bodies[2] = new Body("Earth  ", 2, 3, 24, 25);
bodies[3] = new Body("Mars   ", MARS, 3, 24, 25);
bodies[4] = new Body("Jupiter", JUPITER, 4, 24, 25);
bodies[5] = new Body("Saturn ", SATURN, 5, 24, 25);
bodies[6] = new Body("Uranus ", URANUS, 6, 24, 25);
bodies[7] = new Body("Neptune", NEPTUNE, 7, 24, 25);
bodies[8] = new Body("", 8, 0, 0, 0);
bodies[9] = new Body("Sun    ", SUN, 9, 26, 27);
bodies[10] = new Body("Moon   ", MOON, 10, 28, 29);
bodies[COMET] = new Body("Comet  ", COMET, 2, 24, 25);
bodies[20] = new Body("User object", USER, 2, 24, 25);
function updatePosition(jday, obs) {
	// update body-object with current positions
	// elongation NOT calculated! (use updateElong for that)
	this.p = this.number;
	if (this.p == USER) {
		// fixed/user object
		var altaz = radec2aa(this.ra, this.dec, jday, obs);
		this.alt = altaz[0];
		this.az = altaz[1];
		this.H = altaz[2];
		return;
	}
	var dat = PlanetAlt(this.p, jday, obs);
	this.alt = dat[0];
	this.az = dat[1];
	this.H = dat[2];
	this.ra = dat[3];
	this.dec = dat[4]-(dat[4]>180.0 ? 360 : 0);
	this.eclon = rev(dat[5]);
	this.eclat = dat[6];
	this.r = dat[8];
	this.dist = dat[9];
	this.illum = dat[7];
	this.mag = dat[10];
}
function updateElong(jday, obs) {
	// calculate elongation for object
	if (this.number == SUN) {
		return;
	}
	bodies[SUN].update(jday, obs);
	var ra2 = bodies[SUN].ra;
	var dec2 = bodies[SUN].dec;
	this.update(jday, obs);
	var dat = separation(this.ra, ra2, this.dec, dec2);
	this.elong = dat[0];
	this.pa = dat[1];
}
// heliocentric xyz for planet p
// this is not from Meeus' book, but from Paul Schlyter http://hem.passagen.se/pausch/comp/ppcomp.html
// account for pertuberations of Jupiter, Saturn, Uranus (Uranus and Neptune mutual pertubs are included in elements)
// returns heliocentric x, y, z, distance, longitude and latitude of object
function helios(p, jday) {
	var d = jday-2451543.5;
	var w = p.w[0]+p.w[1]*d;
	// argument of perihelion
	var e = p.e[0]+p.e[1]*d;
	var a = p.a[0]+p.a[1]*d;
	var i = p.i[0]+p.i[1]*d;
	var N = p.N[0]+p.N[1]*d;
	var M = rev(p.M[0]+p.M[1]*d);
	// mean anomaly
	var E0 = M+RAD2DEG*e*sind(M)*(1.0+e*cosd(M));
	var E1 = E0-(E0-RAD2DEG*e*sind(E0)-M)/(1.0-e*cosd(E0));
	while (Math.abs(E0-E1)>0.0005) {
		E0 = E1;
		E1 = E0-(E0-RAD2DEG*e*sind(E0)-M)/(1.0-e*cosd(E0));
	}
	var xv = a*(cosd(E1)-e);
	var yv = a*Math.sqrt(1.0-e*e)*sind(E1);
	var v = rev(atan2d(yv, xv));
	// true anomaly
	var r = Math.sqrt(xv*xv+yv*yv);
	// distance
	var xh = r*(cosd(N)*cosd(v+w)-sind(N)*sind(v+w)*cosd(i));
	var yh = r*(sind(N)*cosd(v+w)+cosd(N)*sind(v+w)*cosd(i));
	var zh = r*(sind(v+w)*sind(i));
	var lonecl = atan2d(yh, xh);
	var latecl = atan2d(zh, Math.sqrt(xh*xh+yh*yh+zh*zh));
	if (p.num == JUPITER) {
		// Jupiter pertuberations by Saturn
		var Ms = rev(planets[SATURN].M[0]+planets[SATURN].M[1]*d);
		lonecl += (-0.332)*sind(2*M-5*Ms-67.6)-0.056*sind(2*M-2*Ms+21)+0.042*sind(3*M-5*Ms+21)-0.036*sind(M-2*Ms)+0.022*cosd(M-Ms)+0.023*sind(2*M-3*Ms+52)-0.016*sind(M-5*Ms-69);
		xh = r*cosd(lonecl)*cosd(latecl);
		// recalc xh, yh
		yh = r*sind(lonecl)*cosd(latecl);
	}
	if (p.num == SATURN) {
		// Saturn pertuberations
		var Mj = rev(planets[JUPITER].M[0]+planets[JUPITER].M[1]*d);
		lonecl += 0.812*sind(2*Mj-5*M-67.6)-0.229*cosd(2*Mj-4*M-2)+0.119*sind(Mj-2*M-3)+0.046*sind(2*Mj-6*M-69)+0.014*sind(Mj-3*M+32);
		latecl += -0.020*cosd(2*Mj-4*M-2)+0.018*sind(2*Mj-6*M-49);
		xh = r*cosd(lonecl)*cosd(latecl);
		// recalc xh, yh, zh
		yh = r*sind(lonecl)*cosd(latecl);
		zh = r*sind(latecl);
	}
	if (p.num == URANUS) {
		// Uranus pertuberations
		var Mj = rev(planets[JUPITER].M[0]+planets[JUPITER].M[1]*d);
		var Ms = rev(planets[SATURN].M[0]+planets[SATURN].M[1]*d);
		lonecl += 0.040*sind(Ms-2*M+6)+0.035*sind(Ms-3*M+33)-0.015*sind(Mj-M+20);
		xh = r*cosd(lonecl)*cosd(latecl);
		// recalc xh, yh
		yh = r*sind(lonecl)*cosd(latecl);
	}
	return new Array(xh, yh, zh, r, lonecl, latecl);
}
// helios()
function radecr(obj, sun, jday, obs) {
	// radecr returns ra, dec and earth distance
	// obj and sun comprise Heliocentric Ecliptic Rectangular Coordinates
	// (note Sun coords are really Earth heliocentric coordinates with reverse signs)
	// Equatorial geocentric co-ordinates
	var xg = obj[0]+sun[0];
	var yg = obj[1]+sun[1];
	var zg = obj[2];
	// Obliquity of Ecliptic (exponent corrected, was E-9!)
	var obl = 23.4393-3.563E-7*(jday-2451543.5);
	// Convert to eq. co-ordinates
	var x1 = xg;
	var y1 = yg*cosd(obl)-zg*sind(obl);
	var z1 = yg*sind(obl)+zg*cosd(obl);
	// RA and dec (33.2)
	var ra = rev(atan2d(y1, x1));
	var dec = atan2d(z1, Math.sqrt(x1*x1+y1*y1));
	var dist = Math.sqrt(x1*x1+y1*y1+z1*z1);
	return new Array(ra, dec, dist);
}
function radec2aa(ra, dec, jday, obs) {
	// Convert ra/dec to alt/az, also return hour angle, azimut = 0 when north
	// DOES NOT correct for parallax!
	// TH0=Greenwich sid. time (eq. 12.4), H=hour angle (chapter 13)
	var TH0 = 280.46061837+360.98564736629*(jday-2451545.0);
	var H = rev(TH0-obs.longitude-ra);
	var alt = asind(sind(obs.latitude)*sind(dec)+cosd(obs.latitude)*cosd(dec)*cosd(H));
	var az = atan2d(sind(H), (cosd(H)*sind(obs.latitude)-tand(dec)*cosd(obs.latitude)));
	return new Array(alt, rev(az+180.0), H);
}
function separation(ra1, ra2, dec1, dec2) {
	// ra, dec may also be long, lat, but PA is relative to the chosen coordinate system
	var d = acosd(sind(dec1)*sind(dec2)+cosd(dec1)*cosd(dec2)*cosd(ra1-ra2));
	// (Meeus 17.1)
	if (d<0.1) {
		d = Math.sqrt(sqr(rev2(ra1-ra2)*cosd((dec1+dec2)/2))+sqr(dec1-dec2));
	}
	// (17.2)
	var pa = atan2d(sind(ra1-ra2), cosd(dec2)*tand(dec1)-sind(dec2)*cosd(ra1-ra2));
	// angle
	return new Array(d, rev(pa));
}
// end separation()
function PlanetAlt(p, jday, obs) {
	// Alt/Az, hour angle, ra/dec, ecliptic long. and lat, illuminated fraction, dist(Sun), dist(Earth), brightness of planet p
	if (p == SUN) {
		return SunAlt(jday, obs);
	}
	if (p == MOON) {
		return MoonPos(jday, obs);
	}
	if (p == COMET) {
		return CometAlt(jday, obs);
	}
	var sun_xyz = sunxyz(jday);
	var planet_xyz = helios(planets[p], jday);
	var dx = planet_xyz[0]+sun_xyz[0];
	var dy = planet_xyz[1]+sun_xyz[1];
	var dz = planet_xyz[2]+sun_xyz[2];
	var lon = rev(atan2d(dy, dx));
	var lat = atan2d(dz, Math.sqrt(dx*dx+dy*dy));
	var radec = radecr(planet_xyz, sun_xyz, jday, obs);
	var ra = radec[0];
	var dec = radec[1];
	var altaz = radec2aa(ra, dec, jday, obs);
	var dist = radec[2];
	var R = sun_xyz[3];
	// Sun-Earth distance
	var r = planet_xyz[3];
	// heliocentric distance
	var k = ((r+dist)*(r+dist)-R*R)/(4*r*dist);
	// illuminated fraction (41.2) 
	// brightness calc according to Meeus p. 285-86 using Astronomical Almanac expressions
	var absbr = new Array(-0.42, -4.40, 0, -1.52, -9.40, -8.88, -7.19, -6.87);
	var i = acosd((r*r+dist*dist-R*R)/(2*r*dist));
	// phase angle
	var mag = absbr[p]+5*log10(r*dist);
	// common for all planets
	switch (p) {
	case MERCURY :
		mag += i*(0.0380+i*(-0.000273+i*0.000002));
		break;
	case VENUS :
		mag += i*(0.0009+i*(0.000239-i*0.00000065));
		break;
	case MARS :
		mag += i*0.016;
		break;
	case JUPITER :
		mag += i*0.005;
		break;
	case SATURN :
		// (Ring system needs special treatment, see Meeus Ch. 45)
		var T = (jday-2451545.0)/36525;
		// (22.1)
		var incl = 28.075216-0.012998*T+0.000004*T*T;
		// (45.1)
		var omega = 169.508470+1.394681*T+0.000412*T*T;
		// (45.1)
		var B = asind(sind(incl)*cosd(lat)*sind(lon-omega)-cosd(incl)*sind(lat));
		var l = planet_xyz[4];
		// heliocentric longitude of Saturn
		var b = planet_xyz[5];
		// heliocentric latitude (do not confuse with 'b' in step 6, page 319)
		// correction for Sun's aberration skipped
		var U1 = atan2d(sind(incl)*sind(b)+cosd(incl)*cosd(b)*sind(l-omega), cosd(b)*cosd(l-omega));
		var U2 = atan2d(sind(incl)*sind(lat)+cosd(incl)*cosd(lat)*sind(lon-omega), cosd(lat)*cosd(lon-omega));
		var dU = Math.abs(U1-U2);
		mag += 0.044*dU-2.60*sind(Math.abs(B))+1.25*sind(B)*sind(B);
		break;
	}
	return new Array(altaz[0], altaz[1], altaz[2], ra, dec, lon, lat, k, r, dist, mag);
}
//
//