Book contents
- Frontmatter
- Contents
- Preface
- Using your personal computer for astronomy
- DEFAULT: default value input routnine & YESNO: ‘Y’ or ‘N’ input routine
- MINSEC: converts between decimal hours/degrees and minutes/seconds form
- JULDAY: calendar date to Julian day number since 1900 January 0.5
- CALDAY: Julian day number since 1900 January 0.5 to calendar date
- TIME: converts between local civil and sidereal times
- EQHOR: converts between equatorial and horizon coordinates
- HRANG: converts between right ascension and hour angle
- OBLIQ: calculates the value of the obliquity of the ecliptic
- NUTAT: finds corrections for nutation in longitude and obliquity
- EQECL: converts between equatorial and ecliptic coordinates
- EQGAL: converts between equatorial and galactic coordinates
- GENCON: converts between any of the coordinate systems
- PRCESS1: approximate precession of equatorial coordinates & PRCESS2: rigorous precession of equatorial coordinates
- PARALLX: converts between geocentric and apparent position
- REFRACT: calculates the effect of atmospheric refraction
- RISET: finds the circumstances of rising and setting
- ANOMALY: solves Kepler's equation for elliptical motion
- SUN: finds the ecliptic coordinates of the Sun
- SUNRS: finds the circumstances of sunrise and sunset
- PELMENT: returns the orbital elements of the major planets
- PLANS: finds the position of a planet
- MOON: finds the position and parallax of the Moon
- MOONRS: finds the circumstances of moonrise and moonset
- MOONNF: finds the times of new and full moon
- ECLIPSE: finds the circumstances of lunar and solar eclipses
- DISPLAY: displays an eclipse in graphical form
- ELOSC: finds positions from osculating elliptical elements
- RELEM: converts elliptic orbital elements from one epoch to another
- PCOMET: finds the position of a comet from parabolic elements
- PFIT: finds parabolic elements from observations & EFIT: finds elliptical elements from observations
- List of variables
- Bibliography
- Index
- PROGRAMS AVAILABLE ON DISK
MOONNF: finds the times of new and full moon
Published online by Cambridge University Press: 17 February 2010
- Frontmatter
- Contents
- Preface
- Using your personal computer for astronomy
- DEFAULT: default value input routnine & YESNO: ‘Y’ or ‘N’ input routine
- MINSEC: converts between decimal hours/degrees and minutes/seconds form
- JULDAY: calendar date to Julian day number since 1900 January 0.5
- CALDAY: Julian day number since 1900 January 0.5 to calendar date
- TIME: converts between local civil and sidereal times
- EQHOR: converts between equatorial and horizon coordinates
- HRANG: converts between right ascension and hour angle
- OBLIQ: calculates the value of the obliquity of the ecliptic
- NUTAT: finds corrections for nutation in longitude and obliquity
- EQECL: converts between equatorial and ecliptic coordinates
- EQGAL: converts between equatorial and galactic coordinates
- GENCON: converts between any of the coordinate systems
- PRCESS1: approximate precession of equatorial coordinates & PRCESS2: rigorous precession of equatorial coordinates
- PARALLX: converts between geocentric and apparent position
- REFRACT: calculates the effect of atmospheric refraction
- RISET: finds the circumstances of rising and setting
- ANOMALY: solves Kepler's equation for elliptical motion
- SUN: finds the ecliptic coordinates of the Sun
- SUNRS: finds the circumstances of sunrise and sunset
- PELMENT: returns the orbital elements of the major planets
- PLANS: finds the position of a planet
- MOON: finds the position and parallax of the Moon
- MOONRS: finds the circumstances of moonrise and moonset
- MOONNF: finds the times of new and full moon
- ECLIPSE: finds the circumstances of lunar and solar eclipses
- DISPLAY: displays an eclipse in graphical form
- ELOSC: finds positions from osculating elliptical elements
- RELEM: converts elliptic orbital elements from one epoch to another
- PCOMET: finds the position of a comet from parabolic elements
- PFIT: finds parabolic elements from observations & EFIT: finds elliptical elements from observations
- List of variables
- Bibliography
- Index
- PROGRAMS AVAILABLE ON DISK
Summary
It is sometimes necessary to calculate the date and time of new or full moon corresponding to a particular calendar month. For example, since a solar eclipse can only occur at new moon, and a lunar eclipse at full moon, we need those times to predict the occurrence of an eclipse. This information could be found using the routine MOON (6000) and its handling program, but it would be a tedious exercise as the phase would have to be calculated several times in an iterative procedure of successive approximation. Routine MOONNF adopts the algorithm given by Meeus in his excellent book Astronomical Formulae for Calculators (second edition) to calculate the instants of new and full moon to within an accuracy of about 2 minutes.
The date is input as usual via the variables DY, MN, and YR. The instants of new and full moon nearest to the date are calculated in terms of the number of Julian days since 1900 January 0.5, being returned by the pairs of variables FI, FF for full moon and NI, NF for new moon. The first variable in each pair indicates the integer number of Julian days of the event since 1900 January 0.5, while the second variable indicates the fraction of the day. The Julian date of new moon is therefore
JD = 2415020 + NI + NF
since 1900 January 0.5 corresponds to Julian date 2415 020.0. Note that Julian days begin at noon, a fact which must be considered when converting to calendar date and time.
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- Information
- Astronomy with your Personal Computer , pp. 172 - 176Publisher: Cambridge University PressPrint publication year: 1990