The Sun Use this option to find, for the date and time you enter, the sun's position (right ascension and declination), altitude and azimuth, nutation in longitude and obliquity, times of sunrise and sunset, and times of beginning and ending of morning and evening astronomical twilight (the time when the upper limb of the sun is 18 degrees below the true horizon). Example entry format: Month Day Year Hrs Min Sec 1 1 1986 12 0 0 The Moon Use this option to find, for the date and time you enter, the moon's position (right ascension and declination), altitude and azimuth, horizontal parallax (the angle subtended by the earth as seen from the moon), distance from the earth, semi-diameter, illuminated fraction, and times of moonrise and moonset. Example entry format: Month Day Year Hrs Min Sec 1 1 1986 12 0 0 The Planets Use this option to find, for the date, time, and planet you enter, the position (right ascension and declination), altitude and azimuth, distance from the earth, elongation, semi-diameter, illuminated fraction, and times of rising and setting (in chronological order). At this time, if you enter "Pluto," ACE displays an error message. Example entry format: Month Day Year Hrs Min Sec Planet 1 1 1986 0 0 0 Mars Eclipses Use this option to list, for the month or year you enter, the circumstances of solar and lunar eclipses visible from any location. After you enter a month and year, you may list eclipses for that month/year combination by entering "M" or for that entire year by entering "Y." For each eclipse ACE lists the UT date and time of the eclipse, the type of eclipse, and the magnitude. For total lunar eclipses ACE gives a more complete list of timings comprising beginning of partial phase, beginning of total phase, maximum eclipse, end of total phase, and end of partial phase. Example entry format: Month Year List[(M)onth, (Y)ear] 1 1986 Y Astrophotography Exposures Use this option to calculate, for the information you enter, exposure times and image sizes needed in lunar and planetary photography. Example entry format: Object Name: Mars Objective Diameter: 200 Focal Length (same units as diameter): 2000 Film Speed (ISO): 100 Object Diameter (" of arc): 30 Magnitude: -2.5 Phase (0-1): 0.95 Filter Factor (1 = no filter): 1 Mean Sidereal Time and Julian Day Use this option to find, for the date, time, right ascension, and declination you enter, the Universal Time, Julian Day Number, Greenwich Mean Sidereal Time, local Mean Sidereal Time, hour angle, altitude, azimuth, airmass (the ratio of atmospheric interference looking toward the object as compared to that looking toward the zenith, on a scale of 1 to infinity, with "***" indicating an object below the horizon), rise, and set. A message will be displayed if the object is circumpolar from your observing site. site. Example entry format: Right Ascension Declination Month Day Year Hrs Min Sec Hrs Min Sec Deg Min Sec 1 1 1986 20 0 0 0 40 0 41 40 0 Precession of Coordinates Use this option to precess forward or backward, for the epochs you enter, the coordinates of an object. Example entry format: From What Epoch? 1950 To What Epoch? 2000 Right Ascension Declination Hrs Min Sec Deg Min Sec 0 40 0 41 40 0 Phases of the Moon Use this option to find, for the month and year you enter, the dates and times of each phase of the moon. Example entry format: Month Year 1 1986 Equinoxes and Solstices Use this option to find, for the year you enter, the UT dates and times of the beginning of the four seasons. Example entry format: Year 1986 Galilean Satellites of Jupiter Use this option to plot graphically the relative positions of the four Galilean satellites of Jupiter. The display starts at the date and time entered. Each subsequent display, updated at a rate set by your computer's speed (about one display per second), shows to scale the satellites' positions relative to the x-axis for the update interval you enter. For example, an update interval of "60" displays the positions as they would appear each hour. An update interval of "0" displays the positions for only the date and time entered. Example entry format: Month Day Year Hrs Min Sec Update Interval (Minutes) 1 1 1986 21 0 0 60 Perpetual Calendar Use this option to display, for the month and year in the Gregorian calendar you enter, the calendar for that month. You may optionally request a printout of the calendar on the printer you designated during the ACE installation process. Example entry format: Month Year Hardcopy[Y/N] 1 1986 N Polaris Use this option to find, for the month, day, and year you enter, the times of the culminations and elongations of Polaris. Example entry format: Month Day Year 1 1 1986 DOS Shell Use this option to execute DOS commands without leaving ACE. To return to ACE, type "EXIT" at the DOS prompt. Exit Use this option when you want to exit from the menu and return to the DOS prompt.  is option when you want to exit from the menu and