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Introduction
How to Use it
"User Manual
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How to use Planetarium
This is a list of the sections below:
General
Selecting a Planet
Compass View
Rise, Set and Twilight Times
Sky View
Setting the Location
Setting the Date and the Time
Stepping through the time
Preferences
General
Planetarium has two main views: Compass view and Sky view. They can be selected by the [C] and [S] buttons at the lower right.
The two text lines at the bottom of the display show the currently selected geographical location and the time which are used for the calculation. Also shown are the local mean sidereal time and the julian date
At the top, there is a (?) button for searching a star, a constellation or a Messier object. Searching and selecting a planet is done with the pull down list at the top right.
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Selecting a Planet
Use the Pulldown menu at the upper right to select the planet you are interested in. In the dials, a line will be drawn from the center to the selected planet. If several planets happen to be at the same spot in the display, they may obscure each other. The selected planet however is drawn last and therefore always visible. The displayed coordinates are also those of the selected planet.
If you are not familiar with the symbols of the planets, tap on a symbol and its name will be shown.
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Compass view
In Compass view, the information for the planets is given in azimuth (the horizontal angle between north and the direction of the planet, counted eastwards) and altitude (the vertical angle between the horizon and the height of the planet). Azimuth is measured in degrees, counted eastwards. (In the preferences window, you can select whether North or South is 0°). Altitude is also measured in degrees, 0° is at the horizon, 90° is at the zenith. Negative values are below horizon
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| The circle at the right of the display shows the azimuth of the planets on a compass scale. To use this dial, turn the Palm Organizer so that 'N' points to the north. (You could also turn the Palm so that the Sun or the Moon icon points to the Sun or to the Moon respectively, if you don't know where north is. During the night you could also try to find Polaris if you are in the northern hemisphere). In the upper right corner, the azimuth of the selected planet is also displayed as a number. 0° is north, 90° is east, and so on. |
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The semicircle on the left shows the altitude. Hold your Palm Organizer upright so that 'Z' points to the zenith. Objects below the horizon line 'H' are not visible at the specified time and location.
In the upper left corner, the altitude of the selected planet is also displayed as a number. 0° is at the horizon, +90° is at the zenith. Negative numbers are below the horizon. |
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| Most people find it difficult to estimate the altitude of an object on the sky. This is a simple trick to improve these estimates. |
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Inside the circle are shown for the selected planet (all topocentric):
- ecliptic coordinates
- the distance (1 AU (Astronomical Unit) is 149.59787e6 km)
- right ascension and declination
The Moon phase is drawn as it can be seen at the specified location and time with the real angular position of the shadow-light line. The number besides it shows the percentage in the cycle. 0.00 is new moon, 50.00 is full moon, 25.00 and 75.00 are first and last quarter respectively. Before 50.00 the Moon is waxing, after 50.00 it is waning.
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| To show the azimuth and altitude of another object than a planet, namely a star or a constellation, press the (?) button and then select the object of your interest. |
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Rise, Set and Twilight Times
Tap the (R/S) button to open the Rise/Set window. (The (R/S) button is only available in Compass view because in Sky view the space is used for other buttons.)
If the [Planets] button is selected, a table is drawn with rise, transit and set times for Sun and Moon and all the planets. Transit time is the time when the object is at the highest point (for the Sun, this is always about noon). Rise and set times are defined for the planets as the time when the object crosses the horizon line. For Sun and Moon, rise and set is when the top of their apparent disk crosses the horizon line. The rise and set time calculations take an atmospheric refraction of about 0.5° into account. A * is shown beside the time to indicate that it is on the following day.
If the [Twilight] button is selected, the rise and set times of the Sun and the twilight times are displayed. Civil, Nautical and Astronomical twilight are defined as the times when the Sun is 6°, 12° and 18° below the horizon respectively. Roughly speaking, Civil twilight is when it's getting dark somewhat and you should switch on the lights of your car. Nautical twilight is when it gets dark enough for some of the brightest stars to be visible in the sky, which were important for nautical purposes, hence the name. Astronomical twilight is when it gets dark enough to be able to observe even the faintest objects.
You can tap on any of the displayed times. This will bring you back to Compass View with that time set. This is useful for example to find out the azimuth of sun rise.
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Sky View
Sky view shows a camera-like image of the sky with the planets and some of the brightest stars as it can be seen at the specified location and time. In the screen shot at the right you can see Jupiter and Saturn well above the horizon. Jupiter is in south eastern direction.
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| The two dials in the corners at the top show the view direction. The left one shows the view altitude, the right one the view azimuth. Tap on these indicators to change the view direction. The view direction can also be changed in steps of 45° horizontally as well as vertically (22.5° when zoomed) by tapping the arrows near the borders of the display. The horizon is drawn as a line, the zenith and nadir are drawn as crosses and the height of 45° above horizon is indicated by a short dashed line. |
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The constellation lines can be switched on and off with the [L] button at the top.
Use the [Z] button to zoom in and out by a factor of 2.
Small symbols are drawn for Messier objects (unless switched off in Preferences). Using the Menu Options/Objects you can extend the list of Messier objects.
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If a star is tapped with the pen, its name and constellation is displayed at the bottom.
If you tap the [S] button while a star's name is shown after tapping it, this star will be centered as much as possible so that it will always be in view when zooming in and out.
To search for a star or a constellation, tap the (?) button and select the object of your interest. The view direction will then be changed in order to center that object and it will be pointed out by a cross hair.
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| For novices it may be difficult to identify the different constellations and stars. To help them get familiar with them, there is a map of the brightest stars in the northern half of the sky, with arrows showing some of the pathways that help observers locate and identify them. Click on the picture at the right to see the full map. |
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Setting the Location
Use the menu item 'Set Location' to set your current geographical position and the zime zone or just tap on the location text at the bottom of the display. If you don't know your longitude or latitude go here and for finding out the time zone go here. There is also website which converts zip codes into latitude, longitude and time zone information (only for North America).
The "Pick" button in the Location window leads to a location pick list where you can store your favourite locations. You can also export this list to the MemoPad or import it from there. In this way you can edit the list on the PC.
The entries below the line are used to set the position and the time zone of the location of your interest.
Above the line are entries for the time zone of the PalmPilot's clock. This is only of importance for the proper function of the [Now] button.
The daylight saving switches add one hour to their respective time zone. Switch them on during summer and off during winter.
In the preferences you can select the display of angles between either decimal degrees (41.4°) or degrees and minutes (41°24'). However this switch only affects the angles displayed by Planetarium. You can always enter angles in both formats. To enter an angle decimal, enter for example 41.4° or just 41.4 . To enter it with degrees and minutes, use one of the following formats: 41°24' or 41:24' or simply 41°24 or 41:24 .
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Setting the Date and the Time
Use the menu item 'Set Time' and 'Set Date' to set the time of the calculation or just tap on the date and the time texts at the bottom of the display.
If the [Now] button is switched on, the time of the Palm Organizer's clock is used and the display is updated every minute.
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Stepping through the time
In the menu 'Time Increment' you can select a time step which is used when pressing one of the Palm's scroll buttons (hardware, not on the display). The odd numbers are multiples of 23h56m (one sidereal day) and are useful for studying planetary motions in Sky view because the stars stay at their positions after each step.
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Preferences
Use the menu item 'Preferences' to select which planets are to be drawn, if your display gets overcrowded. You might know that Uranus, Neptune and Pluto are too faint to be seen by the naked eye, so unless you have a good telescope, you usually turn them off. In this window you will also find a list of the symbols of the planets in case you are not yet familiar with them.
The "Invert Time Step" switch lets you swap the direction of the scroll buttons.
If the 'Invert Sky Map' checkbox is checked, the stars are drawn as white dots on a dark background. This might be useful if you are using
the backlight of the PalmPilot.
If 'Bold stars when zoomed' is checked, the stars are drawn a little bigger when the view is zoomed and constellation lines are turned on, so that they can still be seen when they are on a constellation line.
The Mangitude filter lets you specify how many stars are to be drawn. Planetarium's database contains 1600 stars up to magnitude 5.0 but in urban areas one might see only stars up to mangitude 3.0 due to "light pollution".
The format for displayed angles can be set to either decimal degrees or to degrees with minutes. Note that you can always enter angles in both formats.
The [0°=N] and [0°=S] buttons let you choose the way azimuth is measured. Azimuth is always counted eastwards beginning with 0° at North or South respectively.
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