// Javascript AstroTools
// FUNCTIONS FOR CREATING EPHEMERIDES
// Copyright Ole Nielsen 2002-2004
// Please read copyright notice in astrotools2.html source
var head1="\n";
var head2="";
function nextDate(obs1,dstep,origday) {
// update date and time, origday is day of month at start (some months may not allow this day)
if (dstep < 0) { // dstep is in months (integer!)
dstep = -dstep;
if (dstep >= 12) {
obs1.year += Math.floor(dstep/12);
}
else {
obs1.month += dstep;
if (obs1.month > 12) {
obs1.year++;
obs1.month -= 12;
}
}
month_length[1]=leapyear(obs1.year)?29:28; // check for leapyear
obs1.day = ( origday>month_length[obs1.month-1] ? month_length[obs1.month-1] : origday);
}
else { // dstep is in days (max 31)
var m = Math.round(1440*(dstep-Math.floor(dstep)));
obs1.minutes += m - 60*(Math.floor(m/60));
obs1.hours += Math.floor(m/60);
obs1.day += Math.floor(dstep);
if (obs1.minutes > 59) {
obs1.minutes -= 60;
obs1.hours++;
}
if (obs1.hours > 23) {
obs1.hours -= 24;
obs1.day++;
}
month_length[1]=leapyear(obs1.year)?29:28; // check for leapyear
while (obs1.day > month_length[obs1.month-1]) {
obs1.day -= month_length[obs1.month-1];
obs1.month++;
if (obs1.month == 13) {
obs1.year++;
obs1.month = 1;
}
}
}
} // end nextDate()
function dfrac2tstr(t) {
// returns time string from fraction of day (0 <= t < 1). If t < 0 return '--:--'
if (t < 0 || t >= 1) return "--:--";
t1 = Math.round(1440*t); // round to nearest minute
var hours = Math.floor(t1/60);
var minutes = t1 - 60*hours;
return hmstring2(hours, minutes,0);
}
function pheader(doc,obj,obs,title,descrip,line1,line2) {
// common code for page header
var str = head1 + "Javascript: " + title + head2;
str += "close window
\n";
str += "" + title + "
" + descrip + "
";
if (obj>=0 && obj<100) str += "Object: " + bodies[obj].name + "
";
if (obj==100) str += "Object: All planets
";
str += "Observer location: "+sitename();
str += " (UT "+hmstring(-obs.tz/60.0,true)+")
\n";
var line3="";
for (var i=0; i\n";
str += "close window
\n";
str += "";
doc.write(str);
doc.close();
pwin.focus();
} // end pbottom()
function doTwilightAltAz(obs,obj,dspan,dstep,sunalt) {
// Altitude of object at specified Sun depression (twilight visibility)
var obscopy=new Object(); var obsmax=new Object();
for (var i in obs) {
obscopy[i] = obs[i]; obsmax[i] = obs[i];
}
obscopy.hours = 12; // set to local noon
obscopy.minutes = 0;
if (dstep > 0 && dstep < 1.0) dstep = 1.0; // time step must be at least one day
var pwin=window.open("","twilight","menubar,scrollbars,resizable");
var doc=pwin.document;
var descrip="at the times when the Sun is " + (-sunalt) + "° below the horizon";
var line1=" Morning Twilight Evening Twilight ";
var line2=" Date Time Alt Az Elong Time Alt Az Elong";
pheader(doc,obj,obs,"Twilight Altitude",descrip,line1,line2);
nextDate(obsmax, dspan, obs.day); // 'abuse' nextdate to calculate end time
jdmax = jd(obsmax);
while (true) {
var jday=jd0(obscopy.year,obscopy.month,obscopy.day) + obscopy.tz/1440.0;
if (jday >= jdmax) break;
var rset=sunrise(obscopy,sunalt);
// do line for current date
doc.write(datestring(obscopy));
for (var t=0; t<2; t++) {
doc.write(" " + (rset[2] ? hmstring(rset[t+3],false) : "--:--"));
if (rset[2]) { // false if Sun never reaches specified altitude on this day
bodies[obj].update(rset[t],obscopy);
bodies[obj].elongupdate(rset[t],obscopy);
doc.write(" " + fixnum(bodies[obj].alt, 5, 1));
doc.write(" " + fixnum(bodies[obj].az, 6, 1));
doc.write(" " + fixnum(bodies[obj].elong, 6, 1));
}
else doc.write(" --.- --.- --.-");
}
doc.writeln("");
nextDate(obscopy,dstep);
}
pbottom(doc,pwin,line2);
} // end doTwilightAltAz()
function doAltAz(obs,obj,dt) {
// alt-az of object during one day in steps of dt minutes
var obscopy=new Object(); // make working copy
for (var i in obs) obscopy[i] = obs[i];
var ostr = bodies[obj].name;
var pwin = window.open("","pl_altitude","menubar,scrollbars,resizable");
var doc = pwin.document;
var line2=" Date Time Alt Az Sun Moon";
pheader(doc,obj,obs,"Alt-Azimuth"," ","",line2);
var jday=jd(obscopy);
// for each 0.5 hours do
for (var t = 0; t < 1440/dt; t++) {
doc.write(datestring(obscopy));
doc.write(" " + hmstring2(obscopy.hours,obscopy.minutes,0));
bodies[SUN].update(jday,obs);
var sunalt = bodies[SUN].alt;
bodies[MOON].update(jday,obs);
var moonalt = bodies[MOON].alt;
bodies[obj].update(jday,obs);
doc.write(" " + fixnum(bodies[obj].alt,6,1));
doc.write(" " + fixnum(bodies[obj].az,6,1) + " ");
if (sunalt > -0.833) doc.write(" Day");
else if (sunalt > -6.0) doc.write("Civ-t");
else if (sunalt > -12.0) doc.write("Nau-t");
else if (sunalt > -18.0) doc.write("Ast-t");
else doc.write(" Dark");
if (moonalt > -0.833) doc.writeln(" Up");
else doc.writeln(" Down");
jday += dt/1440.0;
adjustTime(obscopy,dt);
}
pbottom(doc,pwin,line2);
} // end doAltAz()
function doObjectData(obs,obj,dspan,dstep) {
// list object physical data (diameter, illumination, distance, brightness)
// eq. diameters at dist=1 AU/1km
var obscopy=new Object(); var obsmax=new Object();
for (var i in obs) {
obscopy[i] = obs[i]; obsmax[i] = obs[i];
}
var pwin=window.open("","illumdiam","menubar,scrollbars,resizable");
var doc=pwin.document;
var line1=" Date Time Dist(Sun) Dist(Earth) Diam. Illum. Brightn.";
var line2=" [AU] [km] [\"] [%] [mag]";
if (obj!=MOON)
line2=" [AU] [AU] [\"] [%] [mag]";
pheader(doc,obj,obs,"Object Data"," ",line1,line2);
nextDate(obsmax, dspan, obs.day); // 'abuse' nextdate to calculate end time
jdmax = jd(obsmax);
while (true) {
var jday=jd(obscopy);
if (jday >= jdmax) break;
// do line for current date
doc.write(datestring(obscopy));
doc.write(" " + hmstring2(obscopy.hours, obscopy.minutes,0));
bodies[obj].update(jday,obscopy);
var dist = bodies[obj].dist;
var r= bodies[obj].r;
doc.write(fixnum(r,11,3) + " " + (obj==MOON ? fixnum(dist,7,0) : fixnum(dist,7,3)));
if (obj= jdmax) break;
// do line for current date
doc.write(datestring(obscopy));
doc.write(" " + hmstring2(obscopy.hours, obscopy.minutes,0));
bodies[obj].update(jday,obs);
bodies[obj].elongupdate(jday,obs);
var pa = bodies[obj].pa;
doc.write(" " + hmsstring(bodies[obj].ra/15));
doc.write(" " + anglestring(bodies[obj].dec,false,true));
doc.write(fixnum(bodies[obj].alt,7,1));
doc.write(fixnum(bodies[obj].az,8,1));
doc.write(" " + anglestring(bodies[obj].eclon,true,true));
doc.write(" " + anglestring(bodies[obj].eclat,false,true));
doc.write(fixnum(bodies[obj].elong,8,1) + "°" + (pa >= 180 ? " W" : " E"));
doc.writeln("");
nextDate(obscopy, dstep, obs.day);
}
pbottom(doc,pwin,line2);
} // end doPositions()
function doAllPlanets(obs) {
// print data for all planets for ONE day. Positions are for local noon.
var obscopy=new Object();
for (var i in obs) {
obscopy[i] = obs[i];
}
obscopy.hours = 0; // set to local midnight
obscopy.minutes = 0;
var ndiam = [6.72, 16.68, 1, 9.36, 196.88, 165.46, 70.04, 67.0, 1, 1919.3, 716900000.0];
var pwin=window.open("","declination","menubar,scrollbars,resizable");
var doc=pwin.document;
var descrip="Date: " + datestring(obscopy);
var line1="Object Rise Transit Set RA Dec Elong Dist Diam Illum Brightn";
var line2=" [h m s] [deg] [deg] [AU/km] [\"] [%] [mag]";
pheader(doc,-1,obs,"Data for all planets",descrip,line1,line2);
var objects=[9,10,0,1,3,4,5,6,7];
for (var n in objects) {
var obj=objects[n];
var jday=jd(obscopy);
doc.write(bodies[obj].name);
// rise, transit, set
var objevents = findEvents(obj,jday,obs);
var rise=-1; var set=-1; var objtr = -1;
for (var i=objevents.length-2; i>0; i--) { // scan array for relevant events
var t=objevents[i][0]; var e = objevents[i][1];
if (e == -1) rise = t;
if (e == 1) set = t;
if (e == 0) objtr = t;
}
doc.write(" " + dfrac2tstr(rise));
doc.write(" " + dfrac2tstr(objtr));
doc.write(" " + dfrac2tstr(set));
// positions
bodies[obj].update(jday+0.5,obs);
bodies[obj].elongupdate(jday+0.5,obs);
var pa = bodies[obj].pa;
doc.write(" " + hmsstring(bodies[obj].ra/15));
doc.write(" " + anglestring(bodies[obj].dec,false,true));
doc.write(" " + fixnum(bodies[obj].elong,6,1) + "°" + (pa >= 180 ? " W" : " E"));
var dist = bodies[obj].dist;
doc.write(" " + (obj==MOON ? fixnum(dist,7,0) : fixnum(dist,7,3)));
doc.write(" " + fixnum(ndiam[obj]/dist,7,1));
doc.write(" " + fixnum(bodies[obj].illum*100,6,1));
doc.writeln(" " + fixnum(bodies[obj].mag,5,1));
}
pbottom(doc,pwin,line2);
} // doAllPlanets()
function doSeparation(obs,obj1,obj2,dt) {
var obscopy=new Object(); // make working copy
for (var i in obs) obscopy[i] = obs[i];
var pwin = window.open("","pl_altitude","menubar,scrollbars,resizable");
var doc = pwin.document;
var descrip = "of " + bodies[obj1].name + " and " + bodies[obj2].name;
var line1 = " Object 1 Object 2";
var line2 = " Date Time Alt Az Separ. PA Occult. Sun";
pheader(doc,-1,obs,"Separation",descrip,line1,line2);
var jday=jd(obscopy);
// for each dt minutes do
for (var t = 0; t < 1440/dt; t++) {
doc.write(datestring(obscopy));
doc.write(" " + hmstring2(obscopy.hours,obscopy.minutes,0));
bodies[SUN].update(jday,obs);
var sunalt = bodies[SUN].alt;
bodies[obj1].update(jday,obs);
bodies[obj2].update(jday,obs);
alt1=bodies[obj1].alt; alt2=bodies[obj2].alt;
az1=bodies[obj1].az; az2=bodies[obj2].az;
doc.write(" " + fixnum(alt1,6,1) + " " + fixnum(az1,6,1));
var sep = separation(az1,az2,alt1,alt2);
doc.write(" " + fixnum(sep[0],7,2) + "°" + " " + fixnum(sep[1],6,1) + " ");
touchd = (ndiam[obj1]/bodies[obj1].dist + ndiam[obj2]/bodies[obj2].dist)/(2*3600);
if (touchd > sep[0]) // check if occultation (eclipse, transit)
doc.write(" Yes ");
else
doc.write(" ");
if (sunalt > -0.833) doc.write(" Day");
else if (sunalt > -6.0) doc.write("Civ-t");
else if (sunalt > -12.0) doc.write("Nau-t");
else if (sunalt > -18.0) doc.write("Ast-t");
else doc.write(" Dark");
doc.writeln("");
jday += dt/1440.0;
adjustTime(obscopy,dt);
}
pbottom(doc,pwin,line2);
} // end doSeparation()
function doVisible(obs,deepsky,minalt,rasort) {
// show visible stars or DSO
var obscopy=new Object();
for (var i in obs) {obscopy[i] = obs[i]; }
var pwin=window.open("","visible","menubar,scrollbars,resizable");
var doc=pwin.document;
var descrip="Date: " + datestring(obscopy) + " Time: " + hmstring2(obscopy.hours,obscopy.minutes,0);
var line1="";
var line2="Ident Proper name RA Dec Alt Az Rise Transit Set ";
if (deepsky)
line2="Ident Name Const RA Dec Alt Az Rise Transit Set ";
pheader(doc,-1,obs,"Visible " + (deepsky?"Deep sky objects":"Stars"),descrip,line1,line2);
var jday = jd(obscopy);
var ord = new Array(); // for storing records of siderial time and index to catalogue
var sid = local_sidereal(obs);
for (var i=0; i<(deepsky?dso.length:stars.length); i++) {
var h = parsecol(deepsky?dso[i].ra:stars[i].ra) - sid; // negative hour angle
if (h<0) h+=24; if (h>12) h-=24;
ord[i] = new Array(h,i); //
}
if (rasort) isort(ord); // sort according to transit time starting from north
for (var k=0; k<(deepsky?dso.length:stars.length); k++) {
i = ord[k][1];
var ra = (deepsky?dso[i].ra:stars[i].ra);
var de = (deepsky?dso[i].de:stars[i].de);
bodies[20].ra = parsecol(ra)*15; // use User object as temporary object
bodies[20].dec = parsecol(de);
bodies[20].update(jday,obscopy);
if (bodies[20].alt < minalt) continue; // object not visible, skip it
if (deepsky) {
doc.write(fixstr(dso[i].numb,9) + fixstr(dso[i].name,14) + " " + dso[i].cons);
}
else {
doc.write(fixstr(stars[i].star,6) + fixstr(stars[i].cons,4) + fixstr(stars[i].name,14))
}
doc.write(" " + hmsstring(bodies[20].ra/15));
doc.write(" " + anglestring(bodies[20].dec,false,true));
doc.write(" " + fixnum(bodies[20].alt,6,1));
doc.write(" " + fixnum(bodies[20].az,6,1));
var objevents = findEvents(20,jday-0.5,obs); // center "day" on observation time
var rise=-1; var set=-1; var objtr = -1;
for (var j=objevents.length-2; j>0; j--) { // scan array for relevant events
var t=objevents[j][0]+jday-obs.tz/1440; t = t-Math.floor(t);
var e = objevents[j][1];
if (e == -1) rise = t;
if (e == 1) set = t;
if (e == 0) objtr = t;
}
doc.write(" " + dfrac2tstr(rise));
doc.write(" " + dfrac2tstr(objtr));
doc.write(" " + dfrac2tstr(set));
doc.writeln("");
}
pbottom(doc,pwin,line2);
} // end doVisible()
function doDailyEvents(obs,obj,dspan,dstep, sunevents) {
// List daily events (rise, set etc) for one object, optionally include solar events
// obs is a reference variable, make a copy
var obscopy=new Object(); var obsmax=new Object();
for (var i in obs) {
obscopy[i] = obs[i]; obsmax[i] = obs[i];
}
obscopy.hours = 0; // set to local midnight
obscopy.minutes = 0;
if (dstep > 0 && dstep < 1.0) dstep = 1.0; // time step must be at least one day
var ostr = bodies[obj].name;
var pwin=window.open("","daily","menubar,scrollbars,resizable");
var doc=pwin.document;
var line1 = " "; var line2 = " Date ";
if (obj != SUN) {
line1 += " | Object ";
line2 += " | Rise Transit Set ";
}
if (obj == SUN || sunevents) {
line1 += " | Morning Twilight Sun Evening Twilight ";
line2 += " | Astr Naut Civil Rise Transit Set Civil Naut Astr";
}
pheader(doc,obj,obs,"Daily Events","",line1,line2);
nextDate(obsmax, dspan, obs.day); // 'abuse' nextdate to calculate end time
jdmax = jd(obsmax);
while (true) {
var jday=jd0(obscopy.year,obscopy.month,obscopy.day) + obscopy.tz/1440.0;
if (jday >= jdmax) break;
// do line for current date
if (obj != SUN) {
var objevents = findEvents(obj,jday,obs);
var rise=-1; var set=-1; var objtr = -1;
for (var i=objevents.length-2; i>0; i--) { // scan array for relevant events
var t=objevents[i][0]; var e = objevents[i][1];
if (e == -1) rise = t;
if (e == 1) set = t;
if (e == 0) objtr = t;
}
}
if (sunevents || obj == SUN) {
var events = findEvents(SUN,jday,obs);
srise=-1; sset=-1; ctw_b=-1; ctw_e=-1; ntw_b=-1; ntw_e=-1; atw_b=-1; atw_e=-1;
for (var i=events.length-2; i>0; i--) {
var t = events[i][0]; var e = events[i][1];
if (e == 0) suntr = t;
else if (e == -1) srise=t;
else if (e == 1) sset=t;
else if (e == -2) ctw_b = t;
else if (e == 2) ctw_e = t;
else if (e == -3) ntw_b = t;
else if (e == 3) ntw_e = t;
else if (e == -4) atw_b = t;
else if (e == 4) atw_e = t;
}
}
var dw=Math.floor(jday+1.5)-7*Math.floor((jday+1.5)/7);
doc.write(datestring(obscopy) + " " + dow[dw]);
if (obj != SUN) {
doc.write(" " + dfrac2tstr(rise) + " " + dfrac2tstr(objtr) + " " + dfrac2tstr(set));
}
if (obj == SUN || sunevents) {
doc.write(" " + dfrac2tstr(atw_b) + " " + dfrac2tstr(ntw_b) + " " + dfrac2tstr(ctw_b));
doc.write(" " + dfrac2tstr(srise) + " " + dfrac2tstr(suntr) + " " + dfrac2tstr(sset));
doc.write(" " + dfrac2tstr(ctw_e) + " " + dfrac2tstr(ntw_e) + " " + dfrac2tstr(atw_e));
}
doc.writeln("");
nextDate(obscopy,dstep);
}
pbottom(doc,pwin,line2);
} // end doDailyEvents()