31:T856,{ let dotplot = Plot.plot({ height: 450, width: 600, grid: true, marginLeft: 60, marginRight: 40, marginTop: 40, marginBottom: 60, insetTop: 0, insetBottom: 0, style: { fontSize: "13px", background: "#fff", color: "#000" }, x: { label: " Azimuth → ", tickPadding: 6, labelOffset: 50, transform: f => f/6, domain: φo <0 ? [-180/6, 180/6] : [0, 360/6] , tickFormat: x => `${6*x}°`, ticks: 10, tickSize: 9, tickRotate: 0 }, y: { label: "↑ Altitude ", labelOffset: 25, transform: f => f/10, tickFormat: x => `${10*x}°`, ticks: 10, tickSize: 10, domain: [0, 90/10] }, caption: html`
Figure: Sun position @ Lat. ${convertAngle(φo)} - Lon. ${convertAngle(λo)}.
– – – Solar path for current day.
—— Analemma over the course of a year for current time.
• Current position of the Sun.`, marks: [ Plot.frame({stroke: "black"}), Plot.ruleY([0]), // Draw the solar path: We detect discontinuities -> The data is split into segments. //Plot.line(solar_path, {x: "x", y: "y", strokeWidth: 2, stroke: "orange", symbol: "times", r: 3}), segmented_solar_path.map(segment => Plot.line(segment .filter(point => point.y >= 0 ), // Filter by y range, { x: "x", y: "y", strokeWidth: 2, stroke: "orange", strokeDasharray: "4,4"})), // Draw the analemma: We detect discontinuities -> The data is split into segments. //Plot.line(analemma, {x: "x", y: "y", strokeWidth: 2, stroke: "crimson"}), segmented_analemma.map(segment => Plot.line(segment .filter(point => point.y >= 0 ), // Filter by y range, { x: "x", y: "y", strokeWidth: 2, stroke: "black" })), // Current position of the Sun Plot.dot(Sun_now.filter(point => point.y >= 0 ), {x: "x", y: "y", stroke: "black", fill: "orange", strokeOpacity: 1, r: 3}), ] }) return dotplot; }32:Tdf5,// Adapted from https://observablehq.com/@mateh/polar-plot function polar_plot(datasets = [], fns = [(t) => t], options = {}) { if (!Array.isArray(fns)) { fns = [fns]; } const { width = 550, height = 500, domain = [90, 0], resolution = 0.1 } = options; const { radius = Math.min(width, height) / 2 - 30 } = options; const svg = d3.create("svg").attr("width", width).attr("height", height); const content = svg .append("g") .attr("transform", "translate(" + width / 2 + "," + height / 2 + ")"); const scale = d3.scaleLinear().domain(domain).range([0, radius]); const grid = (g) => { const gr = g .attr("class", "r axis") .selectAll("g") .data(scale.ticks(10).slice(1)) .enter() .append("g"); gr.append("circle").attr("r", scale); gr.append("text") .attr("y", function (d) { return -scale(d) - 4; }) .attr("transform", "rotate(15)") .style("text-anchor", "middle") .text(function (d) { return d+"°"; }); }; const axis = (g) => { const ga = g .attr("class", "a axis") .selectAll("g") .data(d3.range(0, 360, 30)) .enter() .append("g") .attr("transform", function (d) { return "rotate(" + (d - 90) + ")"; // Adjust axis labels for new orientation }); ga.append("line").attr("x2", radius); ga.append("text") .attr("x", radius + 6) .attr("dy", ".35em") .style("text-anchor", function (d) { return d > 0 && d < 180 ? "start" : null; }) .attr("transform", function (d) { return d > 180 && d < 360 ? "rotate(180 " + (radius + 20) + ",0)" : d == 0 ? "rotate(90 " + (radius + 10) + ",0)" : d == 180 ? "rotate(-90 " + (radius + 15) + ",0)" : null; }) .text(function (d) { return d + "°"; }); }; const line = d3 .lineRadial() .radius((d) => scale(d[1])) .angle((d) => (d[0] * Math.PI / 180) ); const curve = (g, data, className) => { if (data.length > 0) { if (data.length === 1) { const radius = data[0].y; if(radius >0) { const angle = data[0].x; const angleRad = angle * Math.PI / 180; const scaledRadius = scale(radius); const cx = Math.cos(angleRad - Math.PI / 2) * scaledRadius; // Subtracting PI/2 to align with D3's angle convention const cy = Math.sin(angleRad - Math.PI / 2) * scaledRadius; g.append("circle") .attr("class", className) .attr("cx", cx) .attr("cy", cy) .attr("r", 3); // Adjust the radius as needed } } // Filter and split the data into segments const segments = []; let currentSegment = []; data.forEach(d => { if (d.y > 0) { currentSegment.push([d.x, d.y]); } else { if (currentSegment.length > 0) { segments.push(currentSegment); currentSegment = []; } } }); if (currentSegment.length > 0) { segments.push(currentSegment); } segments.forEach(segment => { g.append("path").datum(segment).attr("class", className).attr("d", line); }); } }; content.append("g").call(grid); content.append("g").call(axis); datasets.forEach(({ data, className }) => { content.append("g").attr("class", "data").call(curve, data, className); }); return svg.node(); } 33:T46e,34:T84f,caption_1 = { const offsetHours = Math.floor(Math.abs(UTC_offset_hours)); const offsetMinutes = Math.abs(UTC_offset_hours*60) % 60; const offsetSign = UTC_offset_hours > 0 ? '-' : '+'; return htl.html`

Analemma and solar path
@ Lat. ${convertAngle(φo)} / Lon. ${convertAngle(λo)}.
– – – Solar path for the current day.
—— Analemma for the current time.
• Current position of the Sun.

Assuming UTC ${offsetSign}${String(offsetHours).padStart(2, '0')}:${String(offsetMinutes).padStart(2, '0')} at the selected location:
—— Analemma at 6:00.
—— Analemma at 8:00.
—— Analemma at 10:00.
—— Analemma at 12:00 (noon).
—— Analemma at 14:00.
—— Analemma at 16:00.
—— Analemma at 18:00.
—— Analemma at 20:00.

` } 35:T9fa,// Adapted from https://observablehq.com/@jashkenas/inputs#worldMapCoordinatesDemo function worldMapCoordinates(config = {}) { var n_point; var lon, lat; const { value = [], title, description, width = width_small_map } = Array.isArray(config) ? {value: config} : config; const height = Math.round((210 / 400) * width); [lon, lat] = value[0]; lon = lon != null ? lon : null; lat = lat != null ? lat : null; const formEl = html``; const context = DOM.context2d(width, height); const canvas = context.canvas; canvas.style.margin = "10px 0 3px"; const projection = d3geo .geoNaturalEarth1() .precision(0.1) .fitSize([width, height], { type: "Sphere" }); const path = d3geo.geoPath(projection, context).pointRadius(point_radius); formEl.append(canvas); function draw() { context.fillStyle = "#fff"; context.fillRect(0, 0, width, height); context.beginPath(); path(graticule_Earth); context.lineWidth = 0.35; context.strokeStyle = "#ddd"; context.stroke(); context.beginPath(); path(land); context.fillStyle = "#f4f4f4"; context.fill(); context.beginPath(); path(countries); context.strokeStyle = "#aaa"; context.stroke(); if (lon != null && lat != null) { const pointPath = { type: "MultiPoint", coordinates: [[lon, lat]] }; context.beginPath(); path.pointRadius(point_radius); path(pointPath); context.fillStyle = color; context.fill(); } } canvas.onclick = function(ev) { const { offsetX, offsetY } = ev; var coords = projection.invert([offsetX, offsetY]); lon = +coords[0].toFixed(2); lat = +coords[1].toFixed(2); draw(); canvas.dispatchEvent(new CustomEvent("input", { bubbles: true })); }; draw(); const form = input({ type: "worldMapCoordinates", title, description, display: v => html`

Latitude: ${lat > 0 ? "+" : ""}${lat != null ? lat.toFixed(2) : ""}° (${convertAngle(lat)}) Longitude: ${lon > 0 ? "+" : ""}${lon != null ? lon.toFixed(2) : " "}° (${convertAngle(lon)})

`, getValue: () => [lon != null ? lon : null, lat != null ? lat : null], form: formEl }); return form; }36:T951,// From https://observablehq.com/@jashkenas/inputs#worldMapCoordinatesDemo function input(config) { let { form, type = "text", attributes = {}, action, getValue, title, description, format, display, submit, options } = config; const wrapper = html`

`; if (!form) form = html``; Object.keys(attributes).forEach(key => { const val = attributes[key]; if (val != null) form.input.setAttribute(key, val); }); if (submit) form.append( html`` ); form.append( html`` ); if (title) form.prepend( html`

${title}

` ); if (description) form.append( html`

${description}

` ); if (format) format = typeof format === "function" ? format : d3format.format(format); if (action) { action(form); } else { const verb = submit ? "onsubmit" : type == "button" ? "onclick" : type == "checkbox" || type == "radio" ? "onchange" : "oninput"; form[verb] = e => { e && e.preventDefault(); const value = getValue ? getValue(form.input) : form.input.value; if (form.output) { const out = display ? display(value) : format ? format(value) : value; if (out instanceof window.Element) { while (form.output.hasChildNodes()) { form.output.removeChild(form.output.lastChild); } form.output.append(out); } else { form.output.value = out; } } form.value = value; if (verb !== "oninput") form.dispatchEvent(new CustomEvent("input", { bubbles: true })); }; if (verb !== "oninput") wrapper.oninput = e => e && e.stopPropagation() && e.preventDefault(); if (verb !== "onsubmit") form.onsubmit = e => e && e.preventDefault(); form[verb](); } while (form.childNodes.length) { wrapper.appendChild(form.childNodes[0]); } form.append(wrapper); return form; }37:[{"id":"5a35a251f8436ffaf8816bf04e79d4f535c20ede98cc65649fc7b1b4c5583288433695c2a0aa59473846edbcdd9331980eef177e90755557208adf086b3e19e4","href":"https://static.observableusercontent.com/files/5a35a251f8436ffaf8816bf04e79d4f535c20ede98cc65649fc7b1b4c5583288433695c2a0aa59473846edbcdd9331980eef177e90755557208adf086b3e19e4","name":"world-110m_withlakes.topo.json","type":"application/json","lastModified":1717880069393.659,"size":92469}] 2f:{"title":"Analemma","cells":[{"id":0,"value":"# Analemma","pinned":false,"hidden":false,"mode":"md"},{"id":1218,"value":"

\nAn analemma represents the position of the Sun in the sky at a given location on Earth at the same time of day over the course of a year. \nIt typically forms a figure-eight pattern when plotted on a graph of altitude versus azimuth.\n

","pinned":false,"hidden":false,"mode":"html"},{"id":2317,"value":"

","pinned":false,"hidden":false,"mode":"html"},{"id":740,"value":"

Sun chart: Analemma and solar path

","pinned":false,"hidden":false,"mode":"html"},{"id":1962,"value":"

\nThe polar plot updates continuously to display the current position of the Sun at the selected location (•), the solar path for current day (dotted line), and several analemmas. Note that positions of the Sun below the horizon (i.e., during night, dawn, and dusk) are not shown.\n
➜ Click on the map below to select a location on Earth.\n

","pinned":false,"hidden":false,"mode":"html"},{"id":651,"value":"

\n Sun's equatorial coordinates (independent of location):\n
Right Ascension: α = ${convertAngle(RA_Sun(n))} ↔ RA = ${formatTime(RA_Sun(n)/15)}\n
Declination (Dec): δ = ${convertAngle(Dec_Sun(n))}\n

\n Greenwich mean sidereal time (GMST): ${formatTime(GMST_now)} (${(GMST_now*15).toFixed(2)}°)\n

\n Greenwich mean time (GMT): ${formatTime(UTC(new Date(),new Date().getTimezoneOffset() / 60 ))}\n

","pinned":false,"hidden":false,"mode":"html"},{"id":2129,"value":"container_1 = html`\n

\n ${polar_plot([{data: solar_path, className: 'line-2'},\n {data: analemma_at_time(6), className: 'line-6AM'}, \n {data: analemma_at_time(8), className: 'line-8AM'},\n {data: analemma_at_time(10), className: 'line-10AM'}, \n {data: analemma_at_time(12), className: 'line-12PM'}, \n {data: analemma_at_time(14), className: 'line-2PM'}, \n {data: analemma_at_time(16), className: 'line-4PM'}, \n {data: analemma_at_time(18), className: 'line-6PM'}, \n {data: analemma_at_time(20), className: 'line-8PM'}, \n {data: analemma, className: 'line-1'}, \n {data: Sun_now, className: 'Sun'}])\n }

${caption_1}

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":2319,"value":"

","pinned":false,"hidden":false,"mode":"html"},{"id":332,"value":"map = { return html`

Select a location on Earth / adapt the time zone

`}","pinned":false,"hidden":false,"mode":"ojs"},{"id":2626,"value":"

\n Observer's location:\n
The position selected on the map has the following coordinates:\n
Lat., φ = ${convertAngle(φo)}\n
Lon., λ = ${convertAngle(λo)}\n

","pinned":false,"hidden":false,"mode":"html"},{"id":511,"value":"

\n Your local time: ${formatTime(UTC(now,0))} (according to your web browser information)\n

\n Local mean sidereal time (LMST): ${formatTime(LMST_now)} (${(LMST_now*15).toFixed(2)}°)\n

","pinned":false,"hidden":false,"mode":"html"},{"id":2321,"value":"container_2 = html`\n

${viewof worldMap}

\n\n
${display_custom_hours}\n\n

\n`","pinned":false,"hidden":false,"mode":"ojs"},{"id":1214,"value":"

","pinned":false,"hidden":false,"mode":"html"},{"id":1913,"value":"---\n### Other graphical representation\n\nThe graph below was prepared with the Observable Plot library. It is shown here for information purposes only.\nIndeed, as you can easily figure out, the polar plot used above is a much more appropriate type\nof graph to display the Sun's path.","pinned":false,"hidden":false,"mode":"md"},{"id":1930,"value":"
","pinned":false,"hidden":false,"mode":"html"},{"id":953,"value":"$31","pinned":false,"hidden":false,"mode":"ojs"},{"id":100,"value":"---\n## Appendices","pinned":false,"hidden":false,"mode":"md"},{"id":654,"value":"### Earth","pinned":false,"hidden":false,"mode":"md"},{"id":656,"value":"// Obliquity of the ecliptic\nobliquity_ecliptic_Earth = function(n) {\n return 23.439 - 0.0000004*n;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":535,"value":"### Sun","pinned":false,"hidden":false,"mode":"md"},{"id":567,"value":"// Mean longitude of the Sun, corrected for the aberration of light\nmean_longitude_Sun = function(n) {\n return (280.46+0.9856474*n) % 360\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":597,"value":"// Mean anomaly of the Sun\n// Actually, Mean anomaly of the Earth in its orbit around the Sun, \n// but it is convenient to pretend the Sun orbits the Earth.\nmean_anomaly_Sun = function(n) {\n return (357.528+0.9856003*n) % 360\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":604,"value":"// Ecliptic longitude of the Sun\nLon_Sun =function(n) {\n return mean_longitude_Sun(n) +1.915*Math.sin(mean_anomaly_Sun(n)*Math.PI/180)+0.02*Math.sin(2*mean_anomaly_Sun(n)*Math.PI/180);\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":613,"value":"// Ecliptic latitude of the Sun\n// (The ecliptic latitude of the Sun never exceeds 0.00033°.)\nLat_Sun = 0","pinned":false,"hidden":false,"mode":"ojs"},{"id":616,"value":"// Distance of the Sun from the Earth (in AU)\ndistance_Sun_Earth = function(n) {\n return 1.00014 - 0.01671*Math.cos(mean_anomaly_Sun(n)*Math.PI/180) - 0.00014*Math.cos(2*mean_anomaly_Sun(n)*Math.PI/180);\n} ","pinned":false,"hidden":false,"mode":"ojs"},{"id":620,"value":"// Apparent diameter of the Sun\n// 2θSun (in °)\nTwo_theta_Sun = function(n) {\n const Sun_diameter = 1392000 // km\n return Math.atan(Sun_diameter(n)/(distance_Sun_Earth(n)*1.495978707*100000000))*180/Math.PI\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":660,"value":"// Right Ascension of the Sun\nRA_Sun = function(n) {\n let angle = Math.atan2( Math.cos(obliquity_ecliptic_Earth(n)*Math.PI/180)*Math.sin(Lon_Sun(n)*Math.PI/180), Math.cos(Lon_Sun(n)*Math.PI/180)) * 180/Math.PI;\n if(angle<0)\n return angle + 360;\n else \n return angle;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":673,"value":"// Declination of the Sun\nDec_Sun = function(n) {\n return Math.asin( Math.sin(obliquity_ecliptic_Earth(n)*Math.PI/180)*Math.sin(Lon_Sun(n)*Math.PI/180))*180/Math.PI;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":700,"value":"// Hour Angle\nHA_Sun = function(n) {\n const date = JDToDate(JD2000+n);\n return (LMST(date)*15-RA_Sun(n)+360)/15 %24;\n} ","pinned":false,"hidden":false,"mode":"ojs"},{"id":707,"value":"x_Sun = function(n) {\n return Math.cos(HA_Sun(n)*15*(Math.PI/180))*Math.cos(Dec_Sun(n)*(Math.PI/180));\n} ","pinned":false,"hidden":false,"mode":"ojs"},{"id":711,"value":"y_Sun = function(n) {\n return Math.sin(HA_Sun(n)*15*(Math.PI/180))*Math.cos(Dec_Sun(n)*(Math.PI/180))\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":715,"value":"z_Sun = function(n) {\n return Math.sin(Dec_Sun(n)*(Math.PI/180));\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":718,"value":"x_hor = function(n) {\n return x_Sun(n)*Math.cos((90-φo)*(Math.PI/180)) -z_Sun(n)*Math.sin((90 -φo)*(Math.PI/180))\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":722,"value":"y_hor = function(n) {\n return y_Sun(n)\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":725,"value":"z_hor = function(n) {\n return x_Sun(n) * Math.sin((90-φo)*(Math.PI/180))+ z_Sun(n)*Math.cos((90 -φo)*(Math.PI/180));\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":729,"value":"Azimuth = function(n) {\n let az = φo > 0 ? (Math.atan2(y_hor(n), x_hor(n)) * (180 / Math.PI) + 180) %360 : Math.atan2(-y_hor(n),-x_hor(n)) * (180 / Math.PI) %360;\n return az;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":733,"value":"Altitude = function(n) {\n return Math.asin(z_hor(n))*(180/Math.PI);\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1971,"value":"analemma_at_time = function(hour) {\n const day_0 = n_0 + (hour + UTC_offset_hours)/24;\n const data = [];\n for(var i=0; i<366; i++) {\n data.push({x:Azimuth(day_0+i), y:Altitude(day_0+i)});\n }\n return data;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":962,"value":"analemma = {\n const day_0 = n_0 + 0.5 + n%1;\n const data = [];\n for(var i=0; i<366; i++) {\n data.push({x:Azimuth(day_0+i), y:Altitude(day_0+i)});\n }\n return data;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1259,"value":"segmented_analemma = splitData(analemma);","pinned":false,"hidden":false,"mode":"ojs"},{"id":1028,"value":"solar_path = {\n const num_points = 500;\n const data = [];\n for(var i=0; i point.x >= Azimuth(n) && point.x <= Azimuth(n))","pinned":false,"hidden":false,"mode":"ojs"},{"id":1256,"value":"// Function to detect discontinuities and split data into segments\nfunction splitData(data, threshold = 180) {\n let segments = [];\n let currentSegment = [];\n\n for (let i = 0; i < data.length - 1; i++) {\n currentSegment.push(data[i]);\n\n // Calculate the difference between consecutive azimuths\n let delta = Math.abs(data[i + 1].x - data[i].x);\n if (delta > threshold) {\n // Close the current segment and start a new one\n segments.push(currentSegment);\n currentSegment = [];\n }\n }\n\n // Add the last segment\n currentSegment.push(data[data.length - 1]);\n segments.push(currentSegment);\n\n return segments;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":1773,"value":"### Polar plot","pinned":false,"hidden":false,"mode":"md"},{"id":1431,"value":"$32","pinned":false,"hidden":false,"mode":"ojs"},{"id":1771,"value":"$33","pinned":false,"hidden":false,"mode":"html"},{"id":2571,"value":"$34","pinned":false,"hidden":false,"mode":"ojs"},{"id":387,"value":"### Time","pinned":false,"hidden":false,"mode":"md"},{"id":2578,"value":"viewof autoset_time_zone = Inputs.toggle({label: \"Autoset time zone\", value: false})","pinned":false,"hidden":false,"mode":"ojs"},{"id":408,"value":"viewof time_zone = Inputs.range([-12, 14], {value: new Date().getTimezoneOffset() / (-60), step: 0.25, label: htl.html`UTC time zone
(¼-hour intervals)`})","pinned":false,"hidden":false,"mode":"ojs"},{"id":400,"value":"display_custom_hours = {\n const html = autoset_time_zone? htl.html`

` : htl.html`${viewof time_zone}`; \n yield html;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":278,"value":"UTC_offset_hours = {\n const offset = autoset_time_zone? new Date().getTimezoneOffset() / 60 : -time_zone;\n return offset;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":777,"value":"// Number of days between J2000.0 and first day of the year, Greenwich noon\nn_0 = {\n return JD_0-JD2000;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":539,"value":"// Number of days since J2000.0, Greenwich noon\nn = JD(now)-JD2000;","pinned":false,"hidden":false,"mode":"ojs"},{"id":860,"value":"// calculate the number of days beetween JD2000 and today at midnight\nd_0 = JD_midnight - JD2000","pinned":false,"hidden":false,"mode":"ojs"},{"id":542,"value":"// Julian Date for J2000.0 (noon UT)\nJD2000 = 2451545.0;","pinned":false,"hidden":false,"mode":"ojs"},{"id":558,"value":"now = {\n while (true) {\n yield new Date();\n } \n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":626,"value":"JD_now = JD(UT(now))","pinned":false,"hidden":false,"mode":"ojs"},{"id":629,"value":"JD_midnight = {\n let midnight = new Date(Date.UTC(now.getUTCFullYear(), now.getUTCMonth(), now.getUTCDate(), 0, 0, 0));\n return JD(midnight);\n}\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":744,"value":"// First day of the current year at midnight\nJD_0 = {\n let midnight = new Date(Date.UTC(now.getFullYear(), 0, 1, 0, 0, 0));\n return JD(midnight);\n}\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":807,"value":"GMST_now = GMST(JDToDate(JD_now))","pinned":false,"hidden":false,"mode":"ojs"},{"id":868,"value":"LMST_now = LMST(JDToDate(JD_now))","pinned":false,"hidden":false,"mode":"ojs"},{"id":686,"value":"GMST = function(date) {\n return GMST_hours(date)\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":691,"value":"// LMST in hours\nLMST = function(date) {\n return (GMST(date) + λo/15) % 24;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":547,"value":"JD = UT => (UT / 86400000) + 2440587.5;","pinned":false,"hidden":false,"mode":"ojs"},{"id":552,"value":"UT = date => Date.parse(date);","pinned":false,"hidden":false,"mode":"ojs"},{"id":793,"value":"// JD to Gregorian Date conversion\nfunction JDToDate(JD) {\n return new Date((JD - 2440587.5) * 86400000);\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":275,"value":"UTC = function(date,offset_hours){\n var ut = (date.getHours() + date.getMinutes() / 60 + date.getSeconds() / 3600 + offset_hours) %24;\n ut < 0 ? ut += 24: null;\n return ut;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":47,"value":"GMST_hours = function(date){\n\n // calculate the number of days beetween JD2000 and the date considered at midnight\n let midnight = new Date(Date.UTC(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), 0, 0, 0));\n const d = JD(midnight) - JD2000\n \n // Calculate T_u (number of Julian centuries since J2000.0)\n const Tu = d / 36525;\n\n // Calculate UT in hours\n const ut = date.getUTCHours() + date.getUTCMinutes() / 60 + date.getUTCSeconds() / 3600;\n\n // Calculate GMST in hours\n const GMST = (6.697374558 + 0.06570982441908 * d + 1.00273790935 * ut + 0.000026 * Tu * Tu) % 24;\n\n return GMST;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":180,"value":"function formatTime(hours) {\n const h = Math.floor(hours);\n const remainder = (hours - h) * 60;\n const m = Math.floor(remainder);\n const s = Math.floor((remainder - m) * 60);\n return `${h}h ${String(m).padStart(2, '0')}m ${String(s).padStart(2, '0')}s`;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":382,"value":"### Map","pinned":false,"hidden":false,"mode":"md"},{"id":2161,"value":"viewof worldMap = worldMapCoordinates([[λo_initial, φo_initial]]);","pinned":true,"hidden":false,"mode":"ojs"},{"id":349,"value":"width_small_map = Math.min(550,Math.max(document.documentElement.clientWidth || 0, window.innerWidth || 0)-20)","pinned":false,"hidden":false,"mode":"ojs"},{"id":357,"value":"point_radius = 3","pinned":false,"hidden":false,"mode":"ojs"},{"id":372,"value":"color = \"#228\"","pinned":false,"hidden":false,"mode":"ojs"},{"id":336,"value":"φo_initial = browser_lat_lon[0]? browser_lat_lon[0] : 56.0881 // observer’s latitude (degrees)","pinned":false,"hidden":false,"mode":"ojs"},{"id":375,"value":"λo_initial = browser_lat_lon[1]? browser_lat_lon[1] : 12.6966 // Observer's longitude (degrees)","pinned":false,"hidden":false,"mode":"ojs"},{"id":338,"value":"browser_lat_lon = [geolocation.latitude, geolocation.longitude]","pinned":false,"hidden":false,"mode":"ojs"},{"id":518,"value":"φo = worldMap[1]","pinned":false,"hidden":false,"mode":"ojs"},{"id":521,"value":"λo = worldMap[0]","pinned":false,"hidden":false,"mode":"ojs"},{"id":495,"value":"function convertAngle(angle) {\n // Extract the degrees\n const absoluteAngle = Math.abs(angle);\n\n // Extract the minutes\n const degrees = Math.floor(absoluteAngle);\n const minutesFloat = (absoluteAngle - degrees) * 60;\n const minutes = Math.floor(minutesFloat);\n\n // Extract the seconds\n const seconds = (minutesFloat - minutes) * 60;\n\n // Add sign \n const sign = angle >= 0 ? '+' : '-';\n\n return sign + degrees + \"° \" + minutes + \"' \" + seconds.toFixed(2) + '\"';\n}\n","pinned":false,"hidden":false,"mode":"ojs"},{"id":360,"value":"graticule_Earth = d3.geoGraticule10()","pinned":false,"hidden":false,"mode":"ojs"},{"id":366,"value":"world = FileAttachment(\"world-110m_withlakes.topo.json\").json();","pinned":false,"hidden":false,"mode":"ojs"},{"id":363,"value":"land = topojson.feature(world, world.objects.land)","pinned":false,"hidden":false,"mode":"ojs"},{"id":369,"value":"countries = topojson.feature(world, world.objects.countries)","pinned":false,"hidden":false,"mode":"ojs"},{"id":340,"value":"geolocation = new Promise((resolve, reject) => {\n let myPositionCallbackFunction = (position) => resolve(position.coords);\n let myPositionErrorCallbackFunction = (error) => reject(error.message);\n \n navigator.geolocation.getCurrentPosition(\n myPositionCallbackFunction,\n myPositionErrorCallbackFunction,\n { enableHighAccuracy: true, timeout: 5000 }\n );\n}).catch(error => error);","pinned":false,"hidden":false,"mode":"ojs"},{"id":343,"value":"$35","pinned":false,"hidden":false,"mode":"ojs"},{"id":346,"value":"$36","pinned":false,"hidden":false,"mode":"ojs"},{"id":351,"value":"d3geo = require(\"d3-geo@1\")","pinned":false,"hidden":false,"mode":"ojs"},{"id":354,"value":"d3format = require(\"d3-format@1\")","pinned":false,"hidden":false,"mode":"ojs"}],"files":"$W37","stdlib":"1","titling":"auto"}