Copyright © 2016 Wayne D Grant
Licensed under the MIT License
Implementations of calculations from 'Practical Astronomy with your Calculator or Spreadsheet, 4th Edition' by Peter Duffett-Smith and Jonathan Zwart. Written in Javascript.
| No. | Name | Method(s) |
|---|---|---|
| 1 | Calendars | daysInMonth |
| 2 | The date of Easter | dateOfEaster |
| 3 | Converting the date to the day number | dateToDayNumber, dateToDaysElapsedSinceEpoch |
| 4 | Julian dates | dateToJulianDayNumber, dateToModifiedJulianDayNumber |
| 5 | Converting the Julian date to the Greenwich calendar date | julianDayNumberToDate |
| 6 | Finding the name of the day of the week | dateToDayOfWeek, julianDayNumberToDayOfWeek |
| 7 | Converting hours, minutes and seconds to decimal hours | hoursMinutesSecondsToDecimalHours |
| 8 | Converting decimal hours to hours, minutes and seconds | decimalHoursToHoursMinutesSeconds |
| 9 | Converting the local time to Universal Time (UT) | localTimeToUniversalTime |
| 10 | Converting UT and Greenwich calendar date to local time and date | universalTimeToLocalTime |
| 11 | Sidereal time (ST) | N/A |
| 12 | Conversion of UT to Greenwich sidereal time (GST) | universalTimeToGreenwichSiderealTime |
| 13 | Conversion of GST to UT | greenwichSiderealTimeToUniversalTime |
| 14 | Local sidereal time (LST) | greenwichSiderealTimeToLocalSiderealTime |
| 15 | Converting LST to GST | localSiderealTimeToGreenwichSiderealTime |
| 16 | Ephermeris time (ET) and terrestial time (TT) | N/A |
| No. | Name | Method(s) |
|---|---|---|
| 17 | Horizon coordinates | N/A |
| 18 | Equatorial coordinates | N/A |
| 19 | Ecliptic coordinates | N/A |
| 20 | Galactic coordinates | N/A |
| 21 | Converting between decimal degress and degrees, minutes and seconds | decimalDegreesToDegreesMinutesSeconds, degreesMinutesSecondsToDecimalDegrees |
| 22 | Converting between angles expressed in degrees and angles expressed in hours | decimalHoursToDecimalDegrees, decimalDegreesToDecimalHours, hoursMinutesSecondsToDegreesMinutesSeconds degreesMinutesSecondsToHoursMinutesSeconds |
| 23 | Converting between one coordinate system and another | N/A |
| 24 | Converting between right ascension and hour angle | rightAscensionToHourAngle, hourAngleToRightAscension |
| 25 | Equatorial to horizon coordinate conversion | hourAngleEquatorialToHorizonCoordinates |
| 26 | Horizon to equatorial coordinate conversion | horizonToHourAngleEquatorialCoordinates |
| 27 | Ecliptic to equatorial coordinate conversion | meanObliquityOfTheEcliptic, eclipticToRightAscensionEquatorialCoordinates |
| 28 | Equatorial to ecliptic coordinate conversion | rightAscensionEquatorialToEclipticCoordinates |
| 29 | Equatorial to galactic coordinate conversion | rightAscensionEquatorialToGalacticCoordinates |
| 30 | Galactic to equatorial coordinate conversion | galacticToRightAscensionEquatorialCoordinates |
| 31 | Generalised coordinate transformations | hourAngleEquatorialToRightAscensionEquatorialCoordinates, rightAscensionEquatorialToHourAngleEquatorialCoordinates, eclipticToGalacticCoordinates, galacticToEclipticCoordinates, hourAngleEquatorialToEclipticCoordinates, eclipticToHourAngleEquatorialCoordinates, hourAngleEquatorialToGalacticCoordinates, galacticToHourAngleEquatorialCoordinates, horizonToRightAscensionEquatorialCoordinates, rightAscensionEquatorialToHorizonCoordinates, horizonToEclipticCoordinates, eclipticToHorizonCoordinates, horizonToGalacticCoordinates, galacticToHorizonCoordinates |
| 32 | The angle between two celestial objects | angleBetweenRightAscensionEquatorialCoordinates, angleBetweenEclipticCoordinates |
| 33 | Rising and setting | |
| 34 | Precession | |
| 35 | Nutation | nutation |
| 36 | Aberration | |
| 37 | Refraction | |
| 38 | Geocentric parallax and the figure of the Earth | |
| 39 | Calculating corrections for parallax | |
| 40 | Heliographic coordinates | |
| 41 | Carrington rotation numbers | |
| 42 | Selenographic coordinates | |
| 43 | Atmospheric extinction |
| No. | Section Name | Method(s) |
|---|---|---|
| 44 | Orbits | |
| 45 | The apparent orbit of the sun | |
| 46 | Calculating the position of the sun | |
| 47 | Calculating orbits more precisely | |
| 48 | Calculating the Sun's distance and angular size | |
| 49 | Sunrise and sunset | |
| 50 | Twilight | |
| 51 | The equation of time | |
| 52 | Solar elongations |
| No. | Section Name | Method(s) |
|---|---|---|
| 53 | The planetary orbits | |
| 54 | Calculating the coordinates of a planet | |
| 55 | Finding the approximate positions of the planets | |
| 56 | Perturbations in a planet's orbit | |
| 57 | The distance, light-travel time and angular size of a planet | |
| 58 | The phases of the planets | |
| 59 | The position-angle of the bright limb | |
| 60 | The apparent brightness of a planet | |
| 61 | Comets | |
| 62 | Parabolic orbits | |
| 63 | Binary-star orbits |
| No. | Section Name | Method(s) |
|---|---|---|
| 64 | The Moon's orbit | |
| 65 | Calculating the Moon's position | |
| 66 | The Moon's hourly motions | |
| 67 | The phases of the Moon | |
| 68 | The position-angle of the Moon's bright limb | |
| 69 | The Moon's distance, angular size and horizontal parallax | |
| 70 | Moonrise and moonset | |
| 71 | Eclipses | |
| 72 | The 'rules' of eclipses | |
| 73 | Calculating a lunar eclipse | |
| 74 | Calculating a solar eclipse | |
| 75 | The Astronomical Calendar |