Willkommen zu EasySky
Welcome to EasySky !

EasySky hopes to bring you closer to the night sky (thus the name :-) in a simple manner.

EasySky is fully Windows compatible and runs under Windows 95, 98, 2000, Me, or Windows NT. It uses the full 32-bit power of these operating systems and the user interface complies to the Windows standard, so there is no time-consuming learning curve.

It is a so called "MDI" program (multiple document interface). This means that you can open as many different documents (views) as you like simultaneously.

With EasySky you can view the night sky as seen from earth but you can also make a trip to our solar system and see the planets, asteroids, and comets as they move through the heavens.

EasySky has many animation possibilities, which show you different astronomical facts in a very graphical  way. You can also examine the included example files.

You can obtain the latest info at any time, on the internet, at the EasySky website http://www.easysky.de/eng/.

Commands:

Menu File

Menu View

Menu Animation

Menu Settings

Menu Tools

Menu Window

Menu Help

When you start using EasySky it is recommended to have a look at the tutorial.

Next: remember the keyboard shortcuts and the handling of the mouse – they will speed up working with EasySky.


Der Autor
The author

As computer scientist and enthusiastic amateur astronomer, I have always been interested in the relationship  between "computer and astronomy". There are many things to calculate in the sky, and today's superfast computers can offer valuable assistance. The graphic representations available today offer numerous possibilities.

I began in about 1990 - back then still in DOS - to simply plot stars on the screen by their celestial coordinates. The next experiment was to show star magnitudes (brightness) with different grey levels; in a darkened room the image of Orion (this was the first constellation I tried) seemed unbelievably realistic.

When time went by I added more functions, till I determined that the program had progressed to a level where it could realistically be offered for sale. So Version 1.0 of  "PC Sternhimmel" (as it was called back then) came into being in March 1992. With the addition of further functions "PC Sternhimmel 2.0" was released in March 1994.

In 1994 I started concentrating on the  Windows version, which you now have in front of you, this was ready in April 2000. I upgraded from Turbo Pascal (Borland) to Visual C++ (Microsoft), to produce a fully Windows-compatible program.

Time did not leave the name unchanged either: I already had plans to translate the program into English, thus "EasySky" was born.

I am an active member of the Starkenburg Observatory in the Southhessen town of Heppenheim, since April 2001 I'm the president of the astronomy club. Feel free to have a look at the observatory internet site: http://www.starkenburg-sternwarte.de

At the moment my main astronomical interest is the positional measurement (astrometry) of minor planets and comets. We send our observations via email to the Minor Planet Center. which apart from being fun, contributes valuable scientific data to the field of minor planet research. For this reason it is also a central theme of EasySky (for example in the solar system depictions).

Matthias Busch

Contact email:  Matthias.Busch@t-online.de*!ExecFile(mailto:Matthias.Busch@t-online.de)


Die Himmelsansicht
The sky view

In a sky view EasySky shows you the starlit sky as it is seen from a special location  at a special time, just like in a planetarium.

Use the arrow keys to move around the sky in every direction, and the zoom commands to enlarge or downsize the view.

You can use the command view settings to adjust which objects or lines should be drawn. Here you can for example switch between a horizontal view (zenith above) or a star map display (celestial north pole above). Define how many comets and asteroids EasySky should show, specify the limiting magnitude for stars, and much more.


Die Sonnensystem-Ansicht
The solar system view

In a solar system view EasySky shows you our solar system as seen from an arbitrary angle.

Besides the placement of the nine major planets also the positions of the comets and minor planets are calculated. You can display any desired orbits to show the aspects of the orbit. Or simply let the heavenly bodies circle around the sun with the animation commands.

Choose between a parallel projection (view from the infinite) and a view from an arbitrary object. E.g. fly on a minor planet in the middle of the asteroid belt.

A view from above at the solar system is impressing if you have switched on all minor planets. Now you see that the asteroid belt between Mars and Jupiter truly deserves its name. Admittedly the distances between the bodies are still in the range of millions of kilometers so that a crash of two of them is extremely unlikely.


Schritt 1 - Neue Himmelsansicht
Step 1 – New sky view

Of course the actual sky tonight is the first thing that interests us.

Choose File – New (Ctrl+N) to create a new document. EasySky will ask you whether you want a sky view or a solar system view. Choose the sky view for the time being.

A new window appears, showing the view to the south at the current time.

To show the ground below the horizon line opaque, switch on the option fill below horizon in the general settings (key E).


Schritt 2 - Ort einstellen
Step 2 – Setting your observing location

Standard location setting in EasySky is the Starkenburg Observatory in Heppenheim, Germany. Change this first to your own home or observing location. Choose the command Location in the menu Settings (or just hit the key L). Select the desired location or add a new one by means of the button New.

EasySky now shows the new location in the title bar. Also note that the view has been newly calculated. You still look to the south, only the situation of the stars has changed.

Tip: Read the section about templates to learn how you can take your location as standard setting.


Schritt 3 - Zeit verstellen
Step 3 – Setting the time

Now we want to change the time to tonight, let's say when the astronomical twilight is finished.

Click on the clock symbol (or press the key T) to open the time dialog. Here you can enter date and time directly, or you jump to dedicated times like the twilight times. Choose astronomical dusk. EasySky has now set the time to the "start of the night".

You see the stars and constellations which stand in the south tonight.

The effectual time is always displayed in the title bar.


Schritt 4 - Bewegen am Himmel
Step 4 – Moving around in the sky

Click on the four buttons with the arrows to move along the sky in all directions. We are now in a view that is aligned to the horizon, so you move relative to the horizon. As an alternative, you can also use the arrow keys of your keyboard.

You change the size of the visible view (zoom in and out) with the magnifier buttons (keys + / -).

If you want information on a certain object, just click on it. EasySky then always searches the object that is nearest to the click.


Schritt 5 - Suchen von Objekten
Step 5 – Searching objects

Use the command search (binocular button or key S) to get any desired object into the middle of the screen fast. Here you find all orientations, objects like planets, comets, stars, galaxies, and so on.

Play around with this command a little bit.

Tip: Most of the buttons in the search dialog have an underlined letter. This one can be used as a abbreviation. So you reach Jupiter for example with the key combination S - J, or the moon with S - M.


Schritt 6 - Animation
Step 6 – Animation

The animation possibilities of EasySky are nearly inexhaustible, I therefore want to give you just a little insight here in this tutorial. Here you also have to try on your own ! Have a look at the examples to the different animation features.

First we want to let the night progress quite slowly. Set the animation speed (temporal distance between two calculations) to one minute with the command speed in the menu animation (or the key A).

With the Icon start (blue "play" triangle) or the enter key you start the animation. The stars and planets move slowly over the sky and finally set in the west. In the east new constellations appear over the horizon. Move with the arrow keys along the horizon, in order to look in all directions.

Tip: All commands are also available during a running animation.

Consider the time, which is always displayed in the title bar.

Next we want to switch off the horizon and go to the star chart mode. To do that, please switch off horizon and user horizon in the settings dialog (key V or "wrench" icon) out and the adjustment to north pole always above.

Now you move the sun into the center with the help of the search objects dialog (key S). In this dialog you check fix at the bottom left corner, then the looked up object (in this case the sun) is held in the center of the screen while the animation is running.

Now change the speed with the key A to 12 hours and start the animation. You see how the sun moves to the left slowly in the course of the days and months in front of the starry background, and how the inner planets Mercury and Venus turn around the sun. Once a month the fast Moon crosses the field of view, and the sun from time to time "overtakes" one of the outer planets.

Stop the animation with the escape key. Now fix one of the planets by keeping the Ctrl key pressed and click on it with the right mouse button (alternatively you can also click on the button Fix in the info box). Restart the animation - now you can easily watch the loop of the respective planet.


Schritt 7 - Objekte suchen
Step 7 – Asteroids and comets

Now we also want these objects to show up which are only visible in a binocular or telescope.

Open up the view settings dialog (key V) and switch on the asteroids first. Attention: because there are so many of them, deactivate the asteroid labelling at the right side of the dialog!

You now have an overwhelming view – the complete asteroid belt. All asteroids are standing sardined in a band along the ecliptic.

Next we restrict the number to be shown and thus click on the button Filter in the view settings dialog just to the right of the asteroids checkbox. The dialog "Asteroid Filter" appears, where you can choose among various filter criteria. For example, switch to until number and enter 1000 into the edit box to show the 1000 first-numbered asteroids. Confirm with OK twice. Now the animation is so speedy that you can let it run with the asteroids switched on. Watch the asteroid performing their loops.

After all also switch on the comets in the view settings dialog, which are then shown as small blue circles with a short tail. This tail has only symbolic meaning and doesn't reflect the actual direction and length of the comet tail.


Schritt 8 - Galaxien, Nebel, Gesichtsfeld
Step 8 – Galaxies, nebulae, field of view

When you are observing the night sky, you are mostly interested in two things:

   a)  Where is the desired observing target located?

   b)  Does it fit into the field of view of my eyepiece, camera, or CCD camera?

EasySky can help you answer both questions.

Let's assume we want to observe the Pleiades first, then the galaxy NGC 891. Switch on Galaxies, Nebulae (until 10m) and also Field of View (CCD, Eyepiece) in the view settings dialog. Then open the search dialog with the key S or the binocular icon.

The button Nebula, Galaxy takes you to a selection list of common nebula names. Choose the Pleiades – by typing the initial letters P - L you can quickly jump there. A double click or OK centers the view on the Pleiades.

Let's suppose that your binocular has a field of view diameter of four degrees. EasySky can now show it as a circle. Mark the option Circle in the command Settings - CCD-Frame, Eyepiece (key R) and specify a diameter of four degrees. Now you see that the Pleiades fit into you field of view very well.

Then search the galaxy NGC 891 (which is showing a pretty nice edge-on view). To do that just enter 891 into the NGC edit field in the search dialog. Now you see that this galaxy is rather small in the binocular view. We now want to set a CCD frame of 21 x 21 arc minutes. Hit the key R again and switch on the option Rectangle. Enter 0 21 (0 degrees, 21 minutes) for width and height. Leave the angle at 0 degrees. Switch off the option Circle.

Now you see that this galaxy is a worthwhile object for that field of view. It couldn't have a better size…


Schritt 9 - Sonnensystem-Ansicht
Step 9 – Solar system view

We will now leave the sky view and address ourselves to the solar system.

Create a new window with File - New (Key Ctrl+N). Select Solar System View from the list.

Now you have two windows on your screen - your sky view and the new solar system view. It's important to notice that the commands New and Open always open new windows. So there are always more windows when time goes by. Close the old window to save computing time. The menu Window shows a list of all currently open windows.

You see our sun in the middle of the screen, furthermore some planets, and the first 10 asteroids. Just click on any object to obtain information about it.


Schritt 10 - Blickwinkel ändern
Step 10 – Changing the Perspective

You can now simply change the angle under which you see the solar system with the arrow keys.

But there is a more elegant method: a right click changes to a mode where you have the complete solar system "at you fingertips" or "at your mouse". This is also being reflected by the cursor. By simply moving the mouse the perspective is changing, and you can now rotate the solar system like you want to.

A second click on the right mouse button quits this mode again.

Attention: this command consumes a lot of computing power. With many objects on the screen it can be rather "bucking".

The keys + and - change the zoom level in a simple manner. So you can see also the outer planets from Saturn to Pluto in a smaller view.


Schritt 11 - Animation
Step 11 – Animation

The animation works the same as in in the sky view, there are the same commands and shortcuts.

Let the planets circle around the sun with the Enter key (Start-Stop). Even while an animation is running you can use all commands (including right click!).

Set the animation speed with the command Animation - Speed (Key A).


Schritt 12 - Orbits und Markierungen
Step 12 – Orbits and markers

EasySky can also show the orbit of every celestial body. Therefore hold down the Ctrl key and click on the desired object. You swicth the orbit off again in the same manner.

Nowe switch on the orbits of Jupiter, Mars, and Earth. You see that the asteroids stay in the zone between Mars and Jupiter, the so-called asteroid belt.

The orbit of an object spatially remains the same (except for minor perturbations). It is determined by the orbital elements. These are six numbers describing for example the semimajor axis of the ellipse or the inclination.

Orbits have abutments (like a huge bridge has), which shall make clear where the orbit is situated above and where below the plain of Earth's orbit, the ecliptic. You can also switch them off (view settings, key V), but then a good portion of the 3D imagination gets lost.

You can mark arbitrary objects to not lose them out of view, for example when you have many objects on screen. Just click on the object with the Shift key held down. The same way you can also remove the marker again.

Additionally, you can switch the orbits and markers on and off in the respective info box of the object (click on the object).


Schritt 13 - Blick von Objekten aus
Schritt 13 – Viewing from an object

We are currently in a parallel projection, which means that we are looking onto the solar system from the "infinite". But we also can settle down onto an arbitrary object.

This is rather easy: Click on the asteroid "(2) Pallas" and then in the info box on the button "Go there". EasySky instantly moves your location to Pallas! You still look in the direction of the sun.

Tip:  There exists an abbreviation: you can move your location onto every object you see (besides the centered object) by Shift-right click.

Now please start the animation again and complete some rounds on Pallas' very inclined orbit. Plunge with it under the ecliptic plain and back upward.

You can also freely choose the viewing direction. Click on the desired object and press the button Fix. EasySky now holds the body always in the center of the viewing field. That way you can create interesting animation effects. For example - view from the asteroid Pallas always towards the Earth or another asteroid.

Tip:  There is a simpler way: you center an object by right click with the Ctrl key held down.


Schritt 14 - Die verschiedenen Klassen von Kleinplaneten
Step 14 – The different categories of asteroids

Now we change back to the overview display. Switch to parallel projection in the view settings dialog (key V). Next center the sun – Search – Sun.

Switch on asteroids in the view settings, and then click on Filter. Here check the switches All and Type, and check out the different types (asteroid groups and families).

For instance - Aten, Amor und Apollo are near-earth asteroids (NEAs), Jupiter Trojans are situated on the orbit of Jupiter, and the distant ones (TNOs, Cubewanos, and Plutinos) are to find out of Neptune's orbit.

Interesting is also the switch PHA (in combination with All) – it shows only the asteroids with a potential danger to Earth (Potentially Hazardous Asteroids).

Four asteroids (to date December 2001) are moving "backward" around the sun. To see them specify All in the filter and set a check mark at the inclination i. Allow only values from 90 to 180 degrees here. An inclination greater than 90 degrees means that the sense of rotation is reverted.

                      --- END ---

This was a small round trip through EasySky, where I couldn't address all the function EasySky is offering. Now it is up to you to practice on, and to slowly get a feeling for the handling of EasySky.

Tip:  Memorize the keyboard shortcuts and the operating of the mouse – they greatly simplify and accelerate the work with EasySky!

Back to the main page


Befehle des Menus Datei
 Commands in the menu "File"

The menu File contains the following commands:

New	Creates a new document
Open	Opens an existing document
Close	Closes the current document
Save	Saves the current document under ist native file name
Save As	Saves the current document under another name
Print	Prints the current document on an arbitrary printer
Page Preview	Displays the document exactly how it would look when it's printed
Print Setup	Lets you choose a printer and make some settings
[Recent Documents]	Here the recently opened documents are listed for quick access
Exit	Quits EasySky


Befehle des Menus Ansicht
Commands in the menu "View"

The menu View contains the following commands:

Zoom in	Scales the view up, that means the visible portion of the sky gets smaller

Zoom out	Scales the view down, that means the visible portion of the sky gets greater

Zoom Level 1	Freely definable zoom level 1

Zoom Level 2	Freely definable zoom level 2

Zoom Level 3	Freely definable zoom level 3

Zoom Level 4	Freely definable zoom level 4

Right 	Moves the visible portion to the right

Left 	Moves the visible portion to the left

Up 	Moves the visible portion up

Down 	Moves the visible portion down

Search	Searching of arbitrary objects

Remove all Trails	Removes all trails which were displayed

Toolbar	Shows/hides the toolbar

Statusbar	Shows/hides the statusbar

Full Screen	Switches to full screen mode (no menus)


Befehle des Menus Animation
Commands in the menu "Animation"

The menu Animation contains all animation relevant commands:

Start (forward)	Starts the animation forward in time

Start (backward)	Starts die Animation backward in time

Single Step (forward)	Switches forward in time for one interval

Single Step (backward)	Switches backward in time for one interval

Stop	Stops the animation

Speed	Here you specify the step size (speed) for the animation


Befehle des Menus Einstellungen
Commands in the menu "Settings"

You can make all settings in the menu Settings:

Time	Setting of the time (sky view)

Time	Setting of the time (solar system view)

Location	Setting of the observing location on Earth

View	View settings (sky view)

View	View settings (solar system view)

User Horizon	Selection of a predefined user horizon

User Objects	Administration of the user objects

CCD Frame, Eyepiece	Settings for the displayable frame

Colors	Color settings

Fonts	Font settings

Legend (Printing)	Apperance of the legend on the hardcopy

General	General settings (for all documents)


Befehle des Menus Extras
Commands in the menu "Tools"

The menu Tools contains the following commands:

Measure Distance	Here you can measure angular or spatial distances between objects

Moon Phases	Shows the phases of the moon for the next year

Jupiters Satellites	Animation of the four bright Jupiter satellites

Slideshow	Shows some astronomical images

Solar System at your Mouse	3D rotating of the solar system directly with the mouse

Document Info	Descriptive Text for the document


Befehle des Menus Fenster
Commands in the menu "Window"

The menu Window contains the following commands:

Cascade	Arranges the windows overlapping

Tile Horizontally	Tiles the windows horizontally (top – bottom)

Tile Vertically	Tiles the windows vertically (left – right)

Arrange Icons	Arranges the to icons minimized windows

[Opened Windows]	Here all currently opened windows are shown


Commands in the menu "?" (Help)

The menu ? (Help) contains the following commands:

Contents and Index	Shows the main help window with the Contents, Index, and Find tabs
Direct Help	Direct Help to icons and commands ("help" mouse cursor)
EasySky WWW Homepage	Directs your browser to the EasySky website http://www.easysky.de/eng/
About EasySky	Info and version number


Der Befehl "Neu" (Menu Datei)
 The command "New" (menu File)

Use this command to create a new document in EasySky. You can specify the type of the file to be created in the dialog New – either a sky view or a solar system view.

EasySky uses the respective template when it creates a new document. You can adjust them according to your needs.

If you want to open an already existing file please use the command open.

Shortcuts

Toolbar:

Keyboard:	Ctrl+N


The dialog "New"

In this dialog you specify the document type you want to create:

-  Sky view  (view from the Earth to the night sky)

-  Solar system view  (overview over the complete solar system)


Der Befehl "Öffnen" (Menu Datei)
 The command "Open" (Menu File)

Use this command to open an already existing document in a new window.

The dialog Open is opening.

It's possible to open several windows simultaneously. Using the menu Window you can switch between multiple opened documents. See also: command Window 1, 2, ...

You can create new documents with the command New.

Shortcuts

Toolbar:

Keyboard:	Ctrl+O


The dialog "Open"

The following options allow you to specify the file to open:

Look in

Choose the drive or directory which you want to access.

File name

Enter the file name or choose it from the above list. In that list only those files are displayed which have the file extension specified by you in the field "Files of type".

"Files of type"

Select the type of the file to open:

*.esv  =  Sky views

*.ess  =  Solar system views


Der Befehl "Schließen" (Menu Datei)
The command "Close" (Menu File)

Use this command to close the active document. EasySky then (possibly) suggests to save the changes made to the actual document. If you close a document without saving you will lose all changes taken since you last saved. Before a document without title is closed EasySky shows the dialog Save as and suggests to name and save the document.

A document can also be closed by using the close symbol (cross).

Icon:


Der Befehl "Speichern" (Menu Datei)
The command "Save" (Menu File)

Use this command to save the active document under its momentary name and directory. If it is the first time the document is saved EasySky shows the dialog Save as, so that you can name your document.

If you want to change the name and directory of an existing document use the command Save as.

Shortcuts

Toolbar:

Keyboard:	Ctrl+S


Der Befehl "Speichern unter" (Menu Datei)
The command "Save as" (Menu File)

Use this command to save the active document under a different name. EasySky shows the dialog Save as, where you can specify a new name for your document.

If you just want to save a document under its previously existing name and directory please use the command Save.


The dialog "Save as "

The following options allow you to specify the file name and location for the file to be saved:

Look in

Choose the drive or directory which you want to access.

File name

Enter a new file name to save the document under a new name. EasySky automatically adds the appropriate extension to the name.

"Files of type"

Is equivalent to the file to save:

*.esv  =  Sky views

*.ess  =  Solar system views


Der Befehl "Drucken" (Menu Datei)
The command "Print" (Menu File)

Use this command to print out you sky view or solar system view. The print dialog appears where you can select a printer if you have multiple printers installed.

Tip:  Check the layout of your hardcopy before printing in the Page preview.

Shortcuts

Toolbar:

Keyboard:	Ctrl+P


Printing progress dialog

While EasySky is sending the hardcopy to the printer the dialog Printing is shown.

Choose "Cancel" to do a premature abort of the printing process.


Der Befehl "Seitenansicht" (Menu Datei)
The command "Page Preview" (Menu File)

Use this command to show the active document exactly as it would be printed.

In the page preview toolbar you can zoom in and out or directly start the printing job.


Symbolleiste der Seitenansicht
Page preview toolbar

The toolbar of the page preview window has the following commands:

Print

Directs you to the dialog Print where you can start a printing job.

Next Page

(not used in EasySky)

Previous Page

(not used in EasySky)

One Page/Two Pages

(not used in EasySky)

Zoom In

With this option you can take a closer look to the page.

Zoom Out

Gives you a greater overview over your printed page.

Close

Closes the page preview and returns to normal view.


Der Befehl "Druckereinrichtung" (Menu Datei)
The command "Print Setup" (Menu File)

Use this command to choose a printer and change ist properties (like portrait or landscape printing).


Der Befehl "Vorlage bearbeiten - Himmelsansicht" (Menu Datei)
The command "Edit Template – Sky View" (Menu File)

This command opens the document template for new sky views. The document is marked by a red border to make clear that you are in the template.

Here you can make all the "persistent" settings which shall be used for new sky view documents. This document is later used by EasySky as a template (all settings are copied) for a new document.

Read here more about templates.


Der Befehl "Vorlage bearbeiten - Sonnensystem-Ansicht" (Menu Datei)
The command "Edit Template – Solar System View" (Menu File)

This command opens the document template for new solar system views. The document is marked by a red border to make clear that you are in the template.

Here you can make all the "persistent" settings which shall be used for new solar system view documents. This document is later used by EasySky as a template (all settings are copied) for a new document.

Read here more about templates.


Zuletzt geöffnete Dokumente
Recently opened documents

EasySky remembers up to 10 of the recently opened documents in the menu File. Here you can fetch them back on screen quickly.


Der Befehl "Beenden" (Menu Datei)
The command "Exit" (Menu File)

Use this command to quit EasySky. As an alternative you can, of course, like in any other Windows program, click on the cross in the upper right corner of the main window.

In case you changed something in the actual document (be it only a change of the viewing direction) EasySky is asking you if you want to save.

Shortcuts

Mouse:	Click on the exit-cross in the upper right corner or double click on the system menu in the upper left corner.

Keyboard:	Alt+F4


Die Zoom-Befehle "Größer" und "Kleiner"
The commands "Zoom In" and "Zoom Out" (Menu View)

Use these commands to scale up or scale down the visible portion of the sky.

EasySky displays the actual size of the viewport in the status bar (right side).

To quickly jump to your "favourite zoom levels" use the predefined zoom commands.

Shortcuts

Toolbar:

Keyboard:	+, -


Die vordefinierten Zoom-Befehle "1" bis "4"
The predefined Zoom commands "1" to "4" (Menu View)

... are used to quickly jump to a freely predefined zoom level.

You can assign a certain viewing area size to each one of these four levels with the command Settings. So it is very easy to switch between an overview chart of the sky (1) and the optimized field for printing (4).

Shortcuts

Toolbar:

Keyboard:	1, 2, 3, or 4


Die Befehle zum Bewegen
The panning commands (Menu View)

You can change the viewing direction (pan) with the commands Left, Right, Up, and Down.

Sky view:

Depending on what orientation you have specified in the view settings, you move along the sky or horizon coordinates. With North pole always up the movements refer to right ascension and declination (here you can't move up and down beyond the celestial poles), with Zenith always up they refer to azimuth and altitude. Here Zenith and Nadir limit your up- and down-scrolling abilities.

Solar system view:

In the solar system view these commands only work if you set parallel projection in the view settings. If you look from an object the direction is always determined.

In the parallel projection you specify the direction from where you look at the scene. Up/down sets the inclination (maximum from "above", minimum from "below"), with left/right you move around the target.

Shortcuts

Toolbar:

Keyboard:	arrow keys


Der Befehl "Suchen"
The command "Search" (Menu View)

With Search you have direct, quick access to all objects without having to center them by panning along the sky tediously.

In specific:

Sun and moon

all planets, just click the respective button

Asteroids: choose the desired asteroid in a second dialog. Input of a part of the number or name is sufficient. Attention: the asteroid you look for has to be displayed. Check the view settings where appropriate.

Comets: same as asteroids – choose the desired comet from a list.

User objects

Sky orientations (use also the shortcuts Alt+N (North), Alt+S (South), Alt+W (West), Alt+E (East), and Alt+Z (Zenith)

Messier objects, NGC objects, IC objects: enter the number and click on the button beneath or Enter

Opposition point (the point in the sky opposite to the sun)

Constellations: select the desired constellation from a list

Coordinates: enter right ascension and declination and click on the button beneath or Enter

Shortcuts

Toolbar:

Keyboard:	S, Ctrl+F


Der Befehl "Suchen"
The command "Search" (Menu View)

With Search you have direct, quick access to all objects without having to center them by panning along the sky tediously.

In specific:

Sun and moon

all planets, just click the respective button

Asteroids: choose the desired asteroid in a second dialog. Input of a part of the number or name is sufficient. Attention: the asteroid you look for has to be displayed. Check the view settings where appropriate.

Comets: same as asteroids – choose the desired comet from a list.

Shortcuts

Toolbar:

Keyboard:	S, Ctrl+F


Der Befehl "Alle Spuren löschen"
The command "Remove all Trails" (Menu View)

Remove all trails (planet, comet, and asteroid trails) at once with this command.

If you want to remove only selected trails just click on them and remove them by clicking on the button Delete Trail.

Shortcuts

Toolbar:

Keyboard:	Ctrl+D


Der Befehl "Alle Orbits löschen"
The command "Remove all Orbits" (Menu View)

Remove all orbits (planet, comet, and asteroid orbits) at once with this command.

If you want to remove only selected orbits just click on them and remove the check marker at Orbit.

Shortcuts

Toolbar:

Keyboard:	Ctrl+D


Der Befehl Symbolleiste (Menu Ansicht)
The command Toolbar (Menu View)

This command is used to show/hide the toolbar.

The toolbar contains some icons which serve as abbreviations for the most common commands of EasySky like e.g. File – Open. If the toolbar is displayed a check marker appears beneath this menu entry.

See also: Toolbar.


Symbolleiste
 Toolbar

No open document

Sky view

Solar system view

The toolbar displays at the upper end of the application window below the menu bar. It provides fast access to a lot of EasySky tools by mouse-click.

You can show or hide the toolbar by selecting/deselecting item Toolbar in the menu View.

Tip: Use the context sensitive help command (Shift+F1) to get a short description of the function of the icons.


Der Befehl Statusleiste (Menu Ansicht)
Command Status Bar (Menu View)

Use this command to show or hide the status bar.

The status bar describes the action that is executed in the window and show the state of the lockable keys. When the status bar is displayed the menu item status bar is ticked.

You can find more information on how to use the status bar at status bar.


Statusleiste
Status Bar

The status bar is displayed at the lower margin of the EasySky window. You can show or hide the status bar by selecting/deselecting item Toolbar in the menu View.

While you are navigating through  menus using the arrow keys the left area of the status bar is describing the functio n of the menu items. Descriptions of the of the button functions in the toolbar are displayed in the same way when you click at one of them and keep it pressed. If you don’t want to execute the command triggered by pressing the button remove the mouse pointer from the button prior to releasing the mouse button.


Der Befehl "Ganzer Bildschirm"
 Command "Full Screen" (Menu View)

Use it to switch to a full screen view to get an unlimited view to the sky. Menu, toolbar and status bar are hidden. You also do not longer see a window border.

This command is most useful when you are already familiar with the shortcuts for the EasySky commands. Especially in presentations you can use it to direct the attention of the audience to the important things.

Exit the full screen mode by pressing the Esc or F key.

Even in the full screen mode you can use the menus – use the keyboard to access it:

- use Alt+F to open the "File" Menu, use Alt+T for "Tools"

- F10 and the Arrow down key also bring you to the “File” menu. Navigate using the Arrow keys then.

Tip:  If the task bar is still visible right-click into it and switch on option Auto Hide.

Shortcut

Keyboard:	F


Der Befehl "Start (vorwärts)"
 Command "Start (forward)" (Menu Animation)

Start the sky animation here. EasySky is now incrementing the time and recalculating the sky image continuously. So all movements on the sky can be simulated. Animation speed (time increment) is adjusted with command Speed.

Shortcuts

Toolbar:

Keyboard:	Enter


Der Befehl "Start (rückwärts)"
 Command "Start (backward)" (Menu Animation)

Start the inverse sky animation here. Time is incremented backwards. Animation speed (time increment) is adjusted with command Speed.

Shortcuts

Toolbar:

Keyboard:	Shift+Enter


Der Befehl "Einzelschritt (vorwärts)"
 Command "Single Step (forward)" (Menu Animation)

This command executes one time step forward and recalculates the sky image. The time interval is adjusted command Speed.

Shortcuts

Toolbar:

Keyboard:	Space


Der Befehl "Einzelschritt (vorwärts)"
 Command "Single Step (forward)" (Menu Animation)

This command executes one time step backward and recalculates the sky image. The time interval is adjusted command Speed.

Shortcuts

Toolbar:

Keyboard:	Shift+Space


Der Befehl "Stop"
 Command "Stop" (Menu Animation)

This command stops the running animation..

Shortcuts

Toolbar:

Keyboard:	Esc


Der Befehl "Geschwindigkeit"
 Command "Speed" (Menu Animation)

Adjust the animation speed here by specifying the Time interval between two calculations of the animation. Simply click the appropriate button.

The shortest time interval is one second. That may be useful for showing a sunset. On the other end the intervals can be as long as five years This setting is intended to be used with solar system views to show the movement of the outer planets. Or it can be used to show the precession (activate it in the Display Options) in the sky view when the coordinate grid is visible.

Shortcut

Keyboard:	A


Zeit einstellen (Himmelsansicht)
Command "Time" (Menu Settings, Sky View)

Here you can set the time you want EasySky to calculate the sky view for.

In the upper part of the window enter the date and below of that enter the time of day.

With the check box DST you can specify that the time entered must be treated as Daylight Saving Time. It will be taken into account immediately by adding one hour to the time difference specified in the Location dialog.

In the lower part of the window you find some buttons that enable to go directly to a certain point in time. E.g., to go to sunrise or sunset or to the different states of twilight.

civil:	sun is 7° below horizon ("almost dark")

nautical:	sun is 12° below horizon ("dark")

astronomical:	sun is 18° below horizon (now it’s dark enough to take photographs)

The button system time brings you back to the actual time. It causes EasySky to continue updating the time and updating the sky view every minute (that’s different to the Button Now). In the Settings you can also set the system to update the sky view every second. Then you should have a quite fast computer.

Shortcuts

Toolbar:

Keyboard:	T


Zeit einstellen (Himmelsansicht)
Command "Time" (Menu Settings, Solar System View)

Here you can set the time you want EasySky to calculate the solar system view for.

In the upper part of the window enter the date and below of that enter the time of day.

Enter the difference to UT in the third dialog field within the window. This time difference is positive if you are east of Greenwich. It’s negative if you are west of Greenwich. Central European Time (CET) for example means a difference of +1.

The button system time brings you back to the actual time. It causes EasySky to continue updating the time and updating the solar system view every minute (that’s different to the Button Now). In the Settings you can also set the system to update the solar system view every second. (That doesn’t make much sense here for the movements of the planets, and the other objects in the solar system are too slow for this.)

Shortcuts

Toolbar:

Keyboard:	T


Der Befehl "Ort" (Menu Einstellungen)
 Command "Location" (Menu Settings)

Enter your location on the earth here. Simply select a location from the list. EasySky will update its display immediately

If your location is not in the list, add it to it. Use the button New to open a dialog window where you can enter the name and the geographical coordinates. Longitudes east of Greenwich are negative, west of Greenwich positive. If you know it, enter the Altitude above sea level.

The Time Difference is most important for all calculations performed by EasySky. It’s the difference between the zone time to UT in hours This time difference is positive if you are east of Greenwich. It’s negative if you are west of Greenwich. Central European Time (CET) for example means a difference of +1.

In the lower part of the dialog window you can enter the acronyms for Normal Time and Daylight Saving Time. (In Germany that would be MEZ and MESZ.) These acronyms are used for time displays.

Use the button Edit to modify stored locations. Delete removes not longer needed locations from the list

Important: If you want to use your location as the default for new documents you must set it in the Template.

Shortcuts

Toolbar:

Keyboard:	L


Der Befehl "Anzeige" (Menu Einstellungen)
 Command "Display" (Menu Settings, sky view)

One of the most important dialogs of EasySky. This is the place where you determine which objects are going to be displayed and if the will be tagged or not. The dialog is mostly self-describing. Check a check box to switch on an option.

All settings are stored with the document and the will be restored when the file is opened the next time.

Your preferred displays should be set in the Template so that new documents start using them.

The options in detail:

•	Planets, Sun, Moon

•	Minor Planets – more options are reachable via the button with the three ellipses. Show either all minor planets, or only a limited number of them, or all the minor planets up to a certain brightness level, or a list of selected objects. Additionally, there are lots of filter criteria.

•	Comets – similar to minor planets options. Configure the comets display via the button just as you like.

•	Stars – sometimes it is advisable to switch of stars display for reasons of calculation speed. You can set a minimum brightness or EasySky can automatically set the number of displayed stars (depending on the zoom level).

•	Galaxies, Nebulae – here, too, you can set a minimum brightness.

•	Field of View – shows the field of view you have defined for a CCD camera, for an ocular or for the Telrad Finder.

•	Point of opposition – a small green cross at the side of the sky opposite to the sun. It shows you the region of the sky where all objects are in opposition to the sun.

•	Shadow of Earth – to demonstrate lunar eclipse activate the shadow of the earth. Two circles are displayed – the Umbra and the Penumbra. Their diameters depend on the distance of the moon.

•	Mirroring is useful to compare a sky view with the view in a telescope. You can mirror the image horizontally or vertically. So you can print mirrored star maps

•	Orientation – select between Zenith on top of screen for a display aligned to the horizon – and North pole on top of screen for a star map view. This differentiation is important for animations: If you want to show the daily movement of the skys select Zenith on top of screen and a time interval of minutes. If you want to show the movements of planets and minor planets select North pole on top of screen and a time interval of hours or days.

•	Use Precession – you will need this setting only if you want to get a correct view of the sky even if you go to a point in time very far away from today. Attention – EasySky has to do more calculations then. So the movements on the screen might be slower then.

•	Tagging – switches tagging on or off for the different types of objects. Important: before activating the display of all minor planets you should switch off the tagging...  :-)

•	Horizon switches on or off the line of the horizon and the four quadrant lines.

•	User-defined horizon – an additional user-definable line of horizon. Read more about that here.

•	Equator – the sky’s equator

•	Ecliptic – the plane containing the Earth’s orbit around the sun. In its vicinity you will find the Moon and the Planets.

•	Constellations – the connection lines of the constellations. For some animations it’s sufficient to switch on these lines only and to omit the display of the stars (improves performance).

•	Borders of Constellations – the official border lines of the 88 constellations. You will notice that are not exactly aligned with the sky coordinates. That’s because they were defined in 1875 and in the meantime precession has shifted the network of coordinates.

•	Grid of Coordinates (horizontal) – the coordinate grid aligned with the horizon (Azimuth and Elevation).

•	Grid of Coordinates (equatorial) – the coordinate grid aligned with the equator (Right ascension and Declination

This dialog also allows to fix an arbitrary object (keep it in the center of the screen during an animation). The button with the three ellipses brings you to the same object selection dialog as the Find command

Shortcuts

Toolbar:

Keyboard:	V


Der Befehl "Anzeige" (Menu Einstellungen)
 Command "Display" (Menu Settings, solar system view)

One of the most important dialogs of EasySky. This is the place where you determine which objects are going to be displayed and if the will be tagged or not. The dialog is mostly self-describing. Check a check box to switch on an option.

All settings are stored with the document and the will be restored when the file is opened the next time.

Your preferred displays should be set in the Template so that new documents start using them.

The options in detail:

•	Planets, Sun, Moon

•	Minor Planets – more options are reachable via the button with the three ellipses. Show either all minor planets, or only a limited number of them, or all the minor planets up to a certain brightness level, or a list of selected objects. Additionally, there are lots of filter criteria.

•	Comets – similar to minor planets options. Configure the comets display via the button just as you like.

•	Projection: select from Parallel Projection (View from infinite distance) and from a Location on an arbitrary sky object. Use the button with the three ellipses to select the object. You can also select an arbitrary position in space specified by its coordinates.

•	Direction of View: determines which object will be fixed in the center of the screen. Normally it’s the sun, but you also can follow the movement of any other object. That will work in the Parallel Projection also.

•	Tagging – switches tagging on or off for the different types of objects. Important: before activating the display of all minor planets you should switch off the tagging...  :-)

•	Orbits – makes the orbits of the objects visible.

•	Orbit ”Pillars” – they show if an object is above or below the Ecliptic Plane. That helps to see the three-dimensional character of an orbit.

•	Object ”Pillars” – you can also give ”pillars” to the objects to see if they are above or below the Ecliptic Plane.

•	Vernal Equinox – draws an arrow from the sun in the direction of the Vernal Equinox.

•	Ecliptic Grid – assign a grid to the Ecliptic Plane. You can parameterize the distance of the grid lines (in AU) and the number of squares that will form one side of a big square.

Shortcuts

Toolbar:

Keyboard:	V


Der Befehl "Benutzer-Horizont" (Menu Einstellungen)
 Command "User-defined Horizon" (Menu Settings)

Use this command to select one of the user-defined horizons. Select one from the list and click the OK button.

Important: To display the selected horizon do not forget to activate it in the Display Options.

Here you find the information how to create your own Horizon File.

Shortcut

Keyboard:	H


Der Befehl "Benutzer-Objekte" (Menu Einstellungen)
 Command "User-defined Objects" (Menu Settings)

EasySky’s User-defined Objects give you a simple tool to define sky objects that are not contained in the data base.

For example:

-  newly discovered Minor Planets or Comets whose orbit is not yet calculated

-  Novae or Supernovae

-  stars that should be tagged in a special way

... or other sky objects

A list is displayed where you can add, modify or delete User-defined Objects. When clicking on the button New you can create a new object. Enter name and coordinates (right ascension and declination). As an option you can also enter a brief description.

You can center or fix an arbitrary User-defined Object directly from this list. Select the object before you press the button. More information here.

Shortcut

Keyboard:	U


Der Befehl "CCD-Gesichtsfeld, Okular" (Menu Einstellungen)
 Command "CCD Field of View, Ocular" (Menu Settings)

Select the type of field of view you want EasySky to draw.

Rectangle	for CCD or other photographic devices

Circle	to show fields of view for oculars

Telrad Finder	Telrad Finder is a searching aid that can be attached to a telescope. It shows three illuminated concentric circles with the diameters 4°, 2° and 0,5°.

Check the type of Field of View you want EasySky to draw. You even can display two or three at a time.

Specify the two dimensions (width and height) in degrees for a rectangle. Different ways of writing are allowed, you will see the result right of the edit boxes. The rectangle can be rotated; positive values rotate left.

For a Circle give the diameter in degrees.

At last there is a switch Always centered. When it is activated the frame will always stay in the center of the screen. If not, it will stay on a fix position of the sky.

The position of the frame can be fixed with Ctrl+Click. This will always de-activate automatic centering

Shortcut

 Keyboard:	R


Der Befehl "Farben" (Menu Einstellungen)
 Command "Colors" (Menu Settings)

Specify the display colors for the different objects here.

They are valid for all Sky and Solar System Views and they are stored per-user. Simply click on the Color button to open the color selection dialog.

Use the button Preview to test the effect of a modification without closing the dialog. If you do not want to keep the modification close the dialog with Cancel. The same applies to the button Standard Colors that restores the ”factory settings”.

If an object has two Color buttons then the left one lets you select the color of the object and the right one lets you select the color of the text.

Shortcut

Keyboard:	C


Der Befehl "Fonts" (Menu Einstellungen)
 Command "Fonts" (Menu Settings)

Assign different Fonts to different categories of objects. Use the lists to select the font and assign a font size in Points.

The font list always shows a preview of the font in a yellow Tooltip window

The number of displayed fonts depends on the fonts installed on your system. You can find big collections of fonts in the Internet, many of them are free of charge.


Der Befehl "Legende (Ausdruck)" (Menu Einstellungen)
 Command "Legend (Print)" (Menu Settings)

Set the title of a print of a Sky View or of a Solar System View here.

Besides a title you can enter up to three lines of text. Additionally, EasySky is able to print the location, the time or the coordinates of the center of the image. Activate the appropriate option(s

Location and coordinates are available in Sky Views only.

The lower part of the dialog window contains edit boxes to set the Font and the Font Size for your print.

All settings of the Legend are stored in the active document and are restored when the document is opened the next time. If you want the settings to be valid for all future documents then you have to change the settings in the Template.

Tip: Check the layout of the legend with the Print Preview.

Shortcut

Keyboard:	L


Der Befehl "Allgemein" (Menu Einstellungen)
 Command "General Settings" (Menu Settings)

This is a menu for settings that are independent of documents. They are stored on a per-user base.

In the upper part of the dialog window you can select if EasySky should update the display every minute or every second. An update every second can only be recommended if your computer is fairly fast (faster than 200MHz).

Normally an update every minute is sufficient for most of the objects are moving slowly.

To observe a sunset ”live” (at a big zoom level) it can make sense to alter this setting to update per second.

Use GSC instructs EasySky to use the Hubble Guide Star Catalog. GSC is not part of EasySky. If you have checked GSC, enter the Drive Letter and the directory where the GSC is located on CD or on your hard disk

Fill below Horizon switches between drawing stars below the horizon on or off. For a more natural looking display switch this option to on.

Show Twilight and Day – With this option on the sky is displayed blue on day. This blue becomes darker when the sun goes below the horizon and ends in black when the sun is 18° below the horizon.

Display Brightness indicates if the brightness of Planets, Comets and Minor Planets is shown on the screen.

Display Margin of Moon draws the margin of all of the moon. Otherwise only the margin of the illuminated side is drawn.

At Constellation Names you can switch the names from English to Latin.

In the lower part of the dialog window you can define the four user-definable zoom levels. You can activate them with buttons in the Toolbar or with the keys 1 – 4. The zoom levels are defined by the height n degrees of the field of view.

The last item in this dialog is switching the display of the day of the week in the title bar on or off.

Shortcut

Keyboard:	E


Der Befehl "Messen am Himmel" (Menu Extras)
 Command "Measure Distance" (Menu Tools)

With the command „Measure distance“ one can easily determine distances and differences of coordinates in the sky as well as distances in the Solar System View.

The pointer changes to a ruler. Now click nearby the start object. EasySky independently looks for the nearest object. Now you see the measure-pointer. Click on the second object to display the result.

It will be displayed:

In the Sky View

-	the coordinates of both objects (right ascension and declination)

-	the difference of the coordinates (e.g. useful to move a telescope)

-	the direct distance, measured on a major circle

in the Solar System View:

-	the coordinates of both objects(X,Y,Z – right-angled coordinates in AE)

-	the difference of coordinates

-	the distance in AE and millions of kilometers

-	the polar coordinates of the vector of direction, if the origin is located in the start object (angle in the ecliptic and angle of height)

Shortcuts

Toolbar:

Keyboard:	M


Der Befehl "Mondphasen" (Menu Extras)
 Command "Moon Phases" (Menu Tools)

This is a handy command to prepare observations. It lists the moon phases for the next year with the precise times clearly arranged.

--> Time	This button sets the Time of the selected moon phase, but does not change the rest of the display.

--> Moon	Here you can set the time and center the display on the moon.

Shortcuts

Toolbar:

Keyboard:	P


Der Befehl "Jupitermonde" (Menu Extras)
 Command "Jupiter's Moons" (Menu Tools)

Graphical display of the four big moons of Jupiter Io, Europa, Ganymede and Callisto.

When opening this window, EasySky calculates the positions of the moons relative to Jupiter at the selected time. The time is displayed on the big button at the bottom. Just click on it to change the time. The usual Time-dialog shows up.

With the checkbox "Labels" you can toggle the characters I, E, G and C, which indicate the four moons.

Use the buttons with the right-, left- and stop-symbol to control the animation. You can regulate the speed by changing the time-interval between two calculations.

Shortcuts

Toolbar:

Keyboard:	J


Der Befehl "Diaschau" (Menu Extras)
 Command "Slideshow" (Menu Tools)

In the slideshow you can look at the pictures included with EasySky in full-screen.

The list on the left side of the dialog show all existing pictures. Most of them are CCD-pictures taken at the Starkenburg-Sternwarte Heppenheim. Select as many pictures as you want (multiple selections with pressed Ctrl+ or Shift+Key, or with the button Select all") and click the button Start.

The checkbox Automatically means that the pictures are advanced after a defined time. With this option checked you can set the frequency of the displayed images. Also it is possible to display the selected images in an endless loop.

If this option is disabled you can switch the images forward by clicking the left mouse button and backward by right-clicking. By the way, the mouse buttons also have an effect in the automatic mode.

The color of the border is set with the button Background Color. A color choose dialog shows up.

Finally you can determine whether the pointer is visible during the presentation or not.

Hint: You can add your own images. Just copy them to the directory "images" under the EasySky-directory on your hard disk. At present only the format .bmp (Windows-Bitmap) is supported. Other formats are planned for future versions.

Shortcuts

Toolbar:

Keyboard:	W


Command "Cascade" (Menu Window)

Use this command to cascade all open windows.


Command "Tile horizontally" (Menu Window)

Use this command to tile all open windows horizontally (top – bottom).


Command "Tile vertically" (Menu Window)

Use this command to tile all open windows vertically (left – right).


Command "Arrange Icons" (Menu Window)

Use this command to arrange the icons of minimized windows at the bottom of the main window. If an open document window is located in this area, it could happen that one or all symbols are hidden because they are under the document window.


Die Auflistung der geöffneten Fenster
List of open windows (Menu Window)

In the lower part of the Window Menu resides a list of the open windows. Here you can select and activate one. This way you do not get confused working with many windows on your screen and can quickly switch between windows

If more than 9 files are open at the same time, EasySky displays a small dialog instead.


Hilfe
Command "Contents and Index" (Menu Help)

Use this command to display the table of contents of the EasySky-Helpfile.

Normally the index card Contents is shown, which is subdivided in various books and chapters.

From here on you can jump to the various help topics. Open a book or chapter simply by double-clicking.

On the second index card (Index) you can look for a topic specifically. Just enter the first few characters at the top. On the third index card (Search) you will find a full-text query of the complete help-file.

As soon as the help window is opened, it is possible to click the button Content to go back to the index card.


Der Befehl "Direkthilfe" (Menu Hilfe)
Command "Direct Help" (Menu Help)

Use the command Direct Help to get help for a particular part of EasySky.

If you click the button Direct Help on the toolbar, the pointer changes to an arrow with question mark. Now click somewhere in the EasySky window, e.g. on a button in the taskbar or on a menu item. The corresponding help topic will be displayed.

Shortcuts

Toolbar:

Keyboard:	Shift+F1


Der Befehl "EasySky im WWW " (Menu Hilfe)
Command "EasySky WWW Homepage" (Menu Help)

With this item you easily jump to the Internet pages of EasySky:

     http://www.easysky.de/eng/

Here you will find up-to-date information and files to download.


Der Befehl "Info über EasySky" (Menu Hilfe)
Command "About EasySky..." (Menu Help)

This command shows the info-dialog of EasySky. Here you will find version and date of your copy.


Titelleiste
Title bar

The title bar spans the top border of a window. It contains the name of the active document an the currently set time. In The Sky View mode the location is displayed additionally

The title bar can be dragged with the mouse to move a window.

Tip: Dialog windows can be moved by dragging their title bar as well.

A title bar can contain following elements:

 	SystemMenu, contains the commands to minimize, maximize etc. and shows if the windows contains an Sky View or a Solar System View.

Minimize window

Maximize window

Restore window

Close window


Der Befehl "Größe ändern" (SystemMenu)
Command "Change size" (System menu)

Use this command to display a fourfold pointer, with which you can change the size of the active window by pressing the arrow keys.

After the pointer has become the fourfold pointer:

1.	Press one of the arrow keys (one of the keys Arrow-left, Arrow-right, Arrow-up or Arrow-down), to move the pointer to the border which you want to move.

2.	Press one of the arrow keys to move the border.

3.	Press the Enter key, when the window size matches your requirements.

Remark: This command is not available, of the windows is displayed in the full screen mode.

Shortcuts

Mouse:	Drag the borders at the corners or edges of the window.


Der Befehl "Verschieben" (SystemMenu)
Command "Move" (System menu)

Use this command to display a fourfold pointer, with which you can move the active window by pressing the arrow keys.

Remark: This command is not available in the full screen mode.


Der Befehl "Minimieren" (SystemMenu)
Command "Minimize" (system menu)

Use this command to minimize the EasySky window down to a symbol in the taskbar. Particular document windows within EasySky can be minimized also, they appear as icons at the bottom of the EasySky window.

Button:

Shortcut

Mouse:	Click on the minimize button in the title bar.


Der Befehl "Maximieren" (SystemMenu)
Command "Maximize" (system menu)

Use this command to maximize the active window to the size of the available space.

Button:

Shortcut

Mouse:	Click on the maximize button in the title bar or double click the title bar.


Der Befehl "Nächstes" (Dokument-SystemMenu)
Command "Next" (system menu of documents)

Use this command to switch over to the next open document window. EasySky determines the next window in the order you opened the windows.

Shortcut

Keyboard:	Ctrl+F6


Der Befehl "Schließen" (SystemMenu)
Command "Close" (system menu)

Use this command to close the active window or dialog. Fensters oder Dialogfelds.

A double click on the SystemMenu has the same effect as choosing the command Close.

Button:

Shortcuts

Keyboard: 	Ctrl+F4 closes a document window.

Alt+F4 closes the main windows and shuts down EasySky.


Der Befehl "Wiederherstellen" (SystemMenu)
Command "Restore" (system menu)

Use this command to restore the active window to the size and position before you used Full Screen or Icon.

Button:


Tastaturkürzel
 Keyboard Shortcuts

A	Animation speed

C	Color settings

D	Legend

E	General settings

F	Full screen view

H	Load user-horizon

I	Document info

J	Jupiter's satellites

L	Location

M	Measure

N	Night vision mode

P	Moon phases

R	CCD frame, eyepiece

S	Search

T	Set date and time

U	User objects

V	Display (view) settings

W	Slideshow

Alt+N	North

Alt+E	East

Alt+S	South

Alt+W	West

Alt+Z	Zenith

Ctrl+D	Erase all trails (sky view)

Ctrl+D	Erase all orbits (solar system view)

Ctrl+F	Search

Ctrl+M	Erase all markings (solar system view)

Ctrl+N	New document

Ctrl+O	Open document

Ctrl+P	Print

Ctrl+S	Save document

Ctrl+Tab	To next open window

F1	Help

F2	System time

Shift+F1	Context sensitive help

Ctrl+F6	To next open window

+	Zoom + (bigger)

-	Zoom - (smaller)

1	Zoomlevel 1

2	Zoomlevel 2

3	Zoomlevel 3

4	Zoomlevel 4

Enter	Start animation forwards

Shift+Enter	Start animation backwards

Esc	Stop animation, close full screen mode, close slideshow

Space	Single step forwards

Shift+Space	Single step backwards

Backspace	Single step backwards

Arrow keys	Change direction of view

Page up	To top

Page down	To bottom

Tip:  Also pay attention to the mouse controls


Maussteuerung
 Mouse controls

Simply by clicking the left or right mouse-button in combination with the Ctrl and Shift keys you can find some functions directly that are otherwise only available through dialogs.

Try to get used to using these abbreviations; they make EasySky even easier to use.

Sky view:

Click	object-info

Ctrl+Click	set CCD field of view or eyepiece position

Shift+Click	add trail

Rightclick	move clicked point to middle

Ctrl+Right	fix object

Solar system view:

Click	Object-info

Ctrl+Click	show orbit / erase

Shift+Click	mark object / erase mark

Right Click	change viewing direction dynamically with mouse

Ctrl+Right	fix object

Shift+Right	change location to clicked object

Tip:  Please see also keyboard shortcuts


Weitere Kleinplaneten-Info
Dialog "Further Asteroid Info"

This box shows all the  information about a minor planet, available in the Minor Planet Center MPCORB.DAT database.

Tip: Use the question mark (help) in the box to the upper right, to get help on particular subjects.


Dialog "Kleinplanet wählen"
Dialog "Select Asteroid"

Within this dialog, you can choose one from the list of the actually displayed asteroids.

The up-to-date celestial coordinates and the brightness of the selected asteroid are displayed in the bottom-right corner.

If the list is too long, you also can enter the number or name of the asteroid you are looking for. Even a part of the name is enough. EasySky displays, if an asteroid of the list fits your input.


Dialog "Komet wählen"
Dialog "Select Comet"

Within this dialog you can choose a comet from the list of the actually displayed.

The momentary celestial coordinates and brightness are displayed in the bottom-right corner.


Dialog "Sternbild wählen"
Dialog "Select Constellation"

Here you can choose one from the list of the 88 existing constellation.

The list can be displayed in English as well as in Latin. Use the two bottom-right radio buttons to switch the languages.

Hint: By entering the first character EasySky jumps automatically to the first entry beginning with this character.


Dialog "Kleinplaneten-Filter"
Dialog "Asteroid Filter"

Here you can set how many and which asteroids are displayed by EasySky.

At the top you can narrow down the choice - either all asteroids, all until a certain number; a list Liste of selected asteroids or all within a given magnitude range.

You can limit this selection at the bottom of the dialog with a few filters. These filters can be combined as you like. Just select the criteria you want by clicking the corresponding checkboxes.

Type Filter:

Below Type you can choose one of the main categories, in which asteroids are subdivided: Aten, Apollo, Amor, Mainbelter, Hilda, Jupiter Trojans, Centaur, Plutino, TNO, Cubewano, "Scattered disk".

An asteroid appears on the "Critical List" of the  MPC if it is not observed for a longer time and his orbit gets slowly uncertain.

PHAs (Potentially Hazardous Asteroids) are asteroids, whose orbits are crossing the earth's orbit in a dangerous near manner. Therefore they need special attention.

"One-Opp-Objects" are asteroids, which were observed in only one opposition, which must not be the actual. So these are candidates to be rediscovered.

With "only numbered" you only get asteroids with an assigned number.

"Only unnumbered" on the other hand could be a useful setting to pick objects for an observing program. E.g. you can combine this with a limiting magnitude.

"Only User Asteroids" displays only the objects added by yourself in the file "UserAsteroids.txt". Read more about this hier.

Orbital elements filter:

a	Semi-major axis of the orbit AE

e	Eccentricity of the orbit (0 = circle to 1 = parable)

i	Inclination in degrees (retrograde orbit bigger than 90 degree)

q	Perihelion (nearest point to the sun) of the orbit in AE

Q	Aphel (farthest point from the sun) of the orbit AE

P	Period in years

H	Absolute magnitude

U	Uncertainty (the bigger, the more uncertain is the orbit)


Dialog "Kometen-Filter"
Dialog "Comet filter"

Here you can setup how many and which comets  you wish EasySky to show.

In upper part you will find menu - to select either all comets, one from your own list, or every comet brighter than a particular magnitude.

These choices can be changed by using combinations of filters in the dialog. Just put a cross next to the filters you wish to use.

Filter for orbital elements:

a	Semi-major axis in AU

e	Eccentricity of the orbit (0 = Circle, 1 = Parabola, >1 = Hyperbola)

i	Inclination of the orbit (retrograde orbit more than 90 degrees)

q	Perihelion distance (point closest to the sun) of the orbit in AU

Q	Aphelion distance (point furthest from the sun) of the orbit in AU

P	Period in years

H	Absolute magnitude


Anzeigefenster für Bilder
The image display window

This window serves to display images. To close use the Esc key, the close button above right, or click on the window.


No help available

For this field of the window no help is available.


No help available

For this information field no help is available.


Dokumente
 Documents and windows

EasySky manages both sky view and solar system views in documents.

These will be saved as files just like, for example, your text files.

This means you can collect files with your most often used settings, or save the relevant document from every observing session.

Here are the file extensions:

       *.esv  =  View of the night sky  (EasySky View)

       *.ess  =  View of solar system(EasySky Solar System)

You can create new documents, open already existing documents, save documents, or save under another name.

Many documents can be loaded, they are completely independent from one another. For example you can run more than one animation at the same time.

File the window with the mouse or with the command in the Window menu.

Attention: one mistake that is often made is to open a document without closing the previous one. If the window is maximised you will not see that multiple documents are loaded. This will use memory unnecessarily and can slow the system down.


Definieren eigener Benutzer-Horizonte
 User defined horizon

EasySky offers the possibility to create your own horizon to accurately reflect different observing locations.

To set up your own horizon you must create a text file (e.g. in Windows-Notepad), that contains the individual points.

Place the horizon file in the EasySky file "Data\Horizons" with file extension ".hor". With the  command User Horizon you can select the new file.

Building up the file is very simple : the file contains numbers each of which denotes a point on the horizon. These numbers represent  the azimuth coordinates and the height separated by a space.

Example (Starkenburg Observatory.hor):

2.0 9.8

3.1 8.5

5.0 8.7

8.5 12.7

13.4 11.6

15.3 14.1

16.7 15.4

etc...

The information for Azimuth and Height is in degrees and can include decimals.

Attention:  Azimuth is measured in the astronomical system from south towards west!

0°=South, 90°=West, 180°=North, 270°=East

EasySky connects the last and the first points to complete the horizon.

If you want to leave spaces where the horizon is at 0°, just complete the line with a point of 0° height and move onto another point with a different azimuth. This should also be completed with 0° height.

This can for example be used to show the sea, or an area that has not yet been measured. Otherwise there are no limits on how the horizon  is drawn, you can, for example, go backwards to show the outline of a tree.


Aktualisieren der Kleinplaneten-Daten
 Updating asteroid data

To update minor planet orbital elements please click on Update asteroids in the  EasySky-folder in the Start Menu. This is a small help-program to download the file MPCORB.DAT from the Minor Planet Center from the internet, and to convert it into the binary format used by EasySky.

MPCORB.DAT is a database of the orbital elements of every minor planet with an orbit accurate enough to be included, currently  well over 100.000. This database is automatically updated every day with the newest orbits and is therefore the most current and comprehensive database that exists - apart from that it is the official database issued by a Commission of the IAU (International Astronomical Union).

First of all with the help of the program download the most recent MPCORB.ZIP from the internet, this is a Zip file that contains the  MPCORB.DAT (currently about 6MB, uncompressed over 20 MB, though it is constantly growing).

The address of the database is:

ftp://cfa-ftp.harvard.edu/pub/MPCORB/MPCORB.ZIP

There is also a mirror at:

http://www.astro.cz/mpcorb/MPZORB.ZIP

The second step is the converting of the text file to the format used by EasySky with the Start Conversion button. Beforehand, with the help of the buttons with three spots, set the correct path for MPCORB.DAT and both output files Asteroids.dat and AsteroidInfo.dat. Finally they must be saved in "Data\Asteroids", so that EasySky can process them.

See also:  Adding asteroids


Aktualisieren der Kometen-Daten
 Updating comet data

Updated comet data can be downloaded from the Minor Planet Center on the internet at the following address:

http://cfa-www.harvard.edu/iau/Ephemerides/Comets/Soft00Cmt.txt

Save this file as text file "Comets.txt" in the folder "Data\Comets" in the  EasySky-folder.

See also:  Adding comets


Hinzufügen eigener Kleinplaneten
 User added asteroids

Sometimes it might happen that the MPC minor planet database is not sufficient for your purposes when updating asteroids - for example because a particular asteroid does not have a precise enough orbit to be included in the MPC database. In such cases you can define your own minor planets.

This is done in the file "UserAsteroids.txt" in the  EasySky-folder "Data\Asteroids".

Enter a line for each  minor planet (this must include the designation and orbital elements of the minor planet, in the "Export Format for Minor Planet Orbits" of the MPC). An example can be found in UserAsteroids.txt.

Here is the Original-Documentation of the  Minor Planet Center (the designation, H and G, and the orbital elements MUST be entered, the rest is optional).

Export Format for Minor-Planet Orbits

The column headed `F77' indicates the Fortran 77 format specifier that should be used to read the specified value.

   Columns   F77    Use

    1 -   7  a7     Number or provisional designation

                      (in packed form)

    9 -  13  f5.2   Absolute magnitude, H

   15 -  19  f5.2   Slope parameter, G

   21 -  25  a5     Epoch (in packed form), .0 TT)

   27 -  35  f9.5   Mean anomaly at the epoch, in degrees

   38 -  46  f9.5   Argument of perihelion, J2000.0 (degrees)

   49 -  57  f9.5   Longitude of the ascending node, J2000.0

                      (degrees)

   60 -  68  f9.5   Inclination in degrees, J2000.0 (degrees)

   71 -  79  f9.7   Orbital eccentricity

   81 -  91  f11.8  Mean daily motion (degrees per day)

   93 - 103  f11.7  Semimajor axis (AU)

  106        i1     Uncertainty parameter, U

                    If this column contains `E' it indicates

                    that the orbital eccentricity was assumed.

                    For one-opposition orbits this column can

                    also contain `D' if a double (or multiple)

                    designation is involved or `F' if an e-assumed

                    double (or multiple) designation is involved.

  108 - 116  a10    Reference

  118 - 122  i5     Number of observations

  124 - 126  i3     Number of oppositions

     For multiple-opposition orbits:

     128 - 131  i4     Year of first observation

     132        a1     '-'

     133 - 136  i4     Year of last observation

     For single-opposition orbits:

     128 - 131  i4     Arc length (days)

     133 - 136  a4     'days'

  138 - 141  f4.2   r.m.s residual (")

  143 - 145  a3     Coarse indicator of perturbers

                    (blank if unperturbed one-opposition object)

  147 - 149  a3     Precise indicator of perturbers

                    (blank if unperturbed one-opposition object)

  151 - 160  a10    Computer name

There may sometimes be additional information beyond column 160

as follows:

  162 - 165  z4.4   4-hexdigit flags

                    The bottom 6 bits are used to encode a

                    value representing the orbit type (other

                    values are undefined):

                      Value

                        2  Aten

                        3  Apollo

                        4  Amor

                        8  Hilda

                        9  Jupiter Trojan

                       10  Centaur

                       14  Plutino

                       15  Other resonant TNO

                       16  Cubewano

                       17  Scattered disk

                    Additional information is conveyed by

                    adding in the following bit values:

                       64  Unused

                      128  Unused

                      256  Unused

                      512  Unused

                     1024  Unused

                     2048  Unused

                     4096  Unused

                     8192  1-opposition object seen at

                           earlier opposition

                    16384  Critical list numbered object

                    32768  Object is PHA

  167 - 194  a      Readable designation

  195 - 200  i8     Date of last observation included in

                      orbit solution (YYYYMMDD format)

See also:  Updating asteroids


Hinzufügen eigener Kometen
 User added comets

Comets which are not in the current database (see Updating comet data) can simply be added to "Comets.txt" in the EasySky-folder "Data\Comets".

For each comet enter one line in MPC format.

Here is the Original Documentation of the Minor Planet Center:

Ephemerides and Orbital Elements Format

The column headed `F77' indicates the Fortran 77 format specifier that should be used to read the specified value.

   Columns   F77    Use

    1 -   4  i4     Periodic comet number

    5        a1     Orbit type (generally `C', `P' or `D')

    6 -  12  a7     Provisional designation (in packed form)

   15 -  18  i4     Year of perihelion passage

   20 -  21  i2     Month of perihelion passage

   23 -  29  f7.4   Day of perihelion passage (TT)

   31 -  39  f9.6   Perihelion distance (AU)

   42 -  49  f8.6   Orbital eccentricity

   52 -  59  f8.4   Argument of perihelion, J2000.0 (degrees)

   62 -  69  f8.4   Longitude of the ascending node, J2000.0

                      (degrees)

   72 -  79  f8.4   Inclination in degrees, J2000.0 (degrees)

   82 -  84  i4     Year of epoch for perturbed solutions

   85 -  86  i2     Month of epoch for perturbed solutions

   87 -  88  i2     Day of epoch for perturbed solutions

   92 -  95  f4.1   Absolute magnitude

   97 - 100  f5.1   Slope parameter

  103 -      a      Name

See also:  Updating comet data


Zentrieren und Fixieren
 Centering and Fixing

In many parts of  EasySky (e.g. in the info-dialogs) there are buttons to center and fix. Here the difference will be briefly explained.

Using Center you can move an object to the center of the field. This is only temporary - if an animation is started or is already running, the object will eventually move away from the center.

Using Fix an object is permanently fixed at the center of the field. This also applies when an animation is running; this can be used to follow an object step-by-step. Useful animations in a sky view might be for example, the changing phases of the moon (moon fixed with north pole up) or Mercury and Venus orbiting the sun (sun fixed).

The  Solar system view does not have this option, only Fix is available.


Dokumentvorlagen
 Document templates

Every time you open a new sky view or solar system view, EasySky uses the respective template for all document dependant adjustments.

A template is nothing more than a normal display which can be accessed with the command File - Edit Template - Sky View or Solar System View. You can use it normally and then save.

While editing a template a red frame and text will be shown - be careful not to mix this up with a "normal" document.

Important settings that should be noted in the template are for instance: your location or entering daylight saving time. Otherwise you can configure EasySky exactly as you want.

You may want to set your CCD field of view to the right size or display a list of particular asteroids. No matter what permanent display setting – you always do that in the template.


Eine Spur hinzufügen
 Making trails

This command is found in the info-box over the Trail button, simply click on the desired object to open the info-box.

Trails are the paths of  planets, minor planets, or comets across the background of stars in the sky.

Set up the time difference between points in the "Add trail" dialog, so EasySky can calculate and then join them together with a line. Apart from that enter the number of single steps. From the current time, the time difference, and the number of steps the program will calculate the end time of the trail.

The color can be chosen with the color button.

The start time and end time of the  trail can also be determined by the user, just use the respective change button. After every time change the required number of steps will be calculated by EasySky.

After changing the dialog with OK you will see the new trail. Clicking will cause the info-box to appear, where you can change the color and erase the trail. With the delete trails command you can delete all trails.


Eine Ephemeride rechnen
 Calculating an Ephemeris

This command is found in the info-dialogs over the ephemeris button. Just click on the desired object to open the info-dialog.

An ephemeris is a list of the positions and other relevant information about an object at different times.

In the "Ephemeris" dialog you will see at the top a large field with the output, underneath enter the start date (default is the current setting of the document), then time difference in days, hours and minutes and the number of lines.

Then click on calculate to show the results.

Finally you can configure under "columns" which values EasySky should calculate:

RA.	Right Ascension (celestial longitude), 2000.0

Dec.	Declination (celestial latitude) , 2000.0

l	Heliocentric longitude (°, measured from spring equinox)

b	Heliocentric Latitude (°)

lambda	Geocentric ecliptic longitude (°, measured from  spring equinox)

delta	Distance from the earth (AU)

r	Distance from the sun (AU)

mag	Apparent magnitude

The finished ephemerides can be written into a text file with the save button, to be archived or printed.


Die Informations-Dialoge
 The information dialogs

Click on an object  with the left mouse button to see the relevant information dialog.

In the sky view the dialog always contains:

Right Ascension	Celestial longitude

Declination	Celestial latitude

Hour angle	The time passed since an object crossed the meridian

Azimuth	Horizontal position of an object measured from the south in degrees

Altitude	Height of an object above the horizon in degrees

Rise	Time an object rises (click on button  sets the time)

Transit	Time an object crosses the meridian (click on button  sets the time)

Set	Time an object sets (click on  button  sets the time)

Additional:

Planets, comets, minor planets

Magnitude	Apparent brightness as seen from earth

Sun distance	in AU

Earth distance	in AU

Velocity	relative to the sun in km/s

Stars

PPM-Number	Number of a star in PPM-Catalog ("Positions and Proper Motions")

Spectrum	Spectral class (color) of a star

Proper motion RA.	Proper motion in arcsec. per year of star in right ascension

Proper motion dec. 	Proper motion in arcsec. per year of star in declination

Moon

Distance	Distance of moon in  km

Phase	Illumination in % (100% = full moon, 0% = new moon)

Longitude libration 	Libration in longitude (view "behind" the visible moon)

Latitude libration 	Libration in latitude (view "over & under" the visible moon)

Position angle	Angle of the lunar axis relative to celestial coordinates measured from north to east

Position angle illum.	Position angle of the illuminated part of the moon measured from north to east.

Sun

Distance	Distance from earth in AU

L0	Latitude  (Sun coordinates) of the center of the solar disk

B0 	Longitude  (Sun coordinates) of the center of the solar disk

Position angle	Position angle of solar disk measured from north to east


Kometen-Liste zusammenstellen
 Arranging the list of comets

Here you can select which Comets will be shown. The list on the left shows all available comets, the list on the right the selected comets.

To select comets mark them and use the button ">” to place them into the right list.

The Button Remove will delete the selected comet from the list. Empty will delete the list completely.


Kleinplaneten-Liste zusammenstellen
 Arranging the list of asteroids

Here you can select which asteroids will be shown. On the top left side you can type in the number (if it is a numbered minor planet) or the name of the asteroid. Than you can use the button ">” to add the asteroid to the list on the right.

As an other option, a list of all asteroids can be shown. You can select objects out of this list and add them to the list of objects shown in the program if you use the button ">”. As there are far too many asteroids, the list will only appear if you click on the button fill.

Attention for all users of Windows 95/98: A list box can only show up to 32,768 entries, but there are far more asteroids. That's why some asteroids can not be shown.

With the Button remove you can take an asteroid out of the list of shown asteroids. If you click on empty, the whole list will be deleted.


Standort im Sonnensystem auswählen
 Selecting a location in the solar system

With this dialog, you can select your location in the solar system. This may be either a certain object (planet, asteroid or comet) or a fixed position. Choosing between these categories, you can make your pre-selection.

If you select planet, asteroid or comet, you will find a list of the currently shown objects. You can choose one of them.

If you select co-ordinates you type in your location in rectangular co-ordinates. The unit is the Astronomical Unit (AU). X=Y=Z=0 is the position of the sun. The X-Y-level lies in the earth's orbit (ecliptic).

Note: The same dialog is used to select the viewing direction.


Die mitgelieferten Beispiele
 Enclosed Examples

You will find some EasySky documents (sky view or solar system view) in the subdirectory "Examples" of EasySky.

They will help you find out what the program is able to do. They are divided into thematic sub-folders.

Allow yourself some time to open the different files and to run the animations.

All files have a short description in the document info (in the Tools menu). This description will also appear while loading the files including further information.


The epoch gives the time and date for which the orbital elements are exactly correct.


The mean anomaly M indicates the angle on the orbit, where the object is located at the time of the epoch.


The argument of perihelion gives the angle between the ascending node and the perihelion (as seen from the sun).


The ascending node is the point in the orbit of a heavenly body, where it crosses the plane of the ecliptic from below. This angle is measured from the spring equinox.


The inclination i gives the angle between the orbit of the object and the ecliptic.


The eccentricity e tells how much the orbit differs from a circle. e=0 is exactly a circle, e=1 is a parabolic orbit.


The semi-major axis a is half the larger axis of the orbital ellipse, measured in AU (astronomical units).


The perihelion distance q is the minimum distance of an object from the sun, measured in AU (astronomical units).


The aphelion distance Q is the maximum distance of an object from the sun, measured in AU (astronomical units)).


The period P tells you in years how long an object takes to complete one orbit.


The absolute magnitude H gives the magnitude of the body that it would have if it stood in a distance 1 AU from the earth and also 1 AU from the sun.


The albedo parameter G tells you the reflectivity (albedo) of an object (normally between 0.25 and 0.05).


There are different types of minor planets - Aten, Apollo, Amor, main belt, Hilda, Jupiter-Trojan, Centaur, Plutino, TNO or Cubewano


The Minor Planet Center "critical list" of asteroids contains minor planets which have not been observed for some time, hence the orbits have not been updated and are less precisely known.


PHAs are Potentially Hazardous Asteroids. These minor planets have orbits which closely approach or cross the earth's orbit; they present a small but significant risk of collision with the earth, so special care is taken with these objects.


A "one-opp-object" is a minor planet which has only been observed at one opposition and not at a subsequent opposition(s).

This means that the object was not observed again and is in danger of becoming lost. It is very important to re-observe such  objects.


U ist the so called uncertainty number. It is a measure for the accuracy of the known orbit. The smaller the number, the better. Only the best-known orbits have an U of 0 and 1.


The number of observations  shows how often this object has been observed and measured.


The observed arc indicates how long the object has been observed. (Either the number of days or the year of the first and last observation will be shown.)


This indicates the date of the last observation of the minor planet. If the last observation has been some time ago, it may be worth re-measuring the object. This will improve the calculated orbit.


Number of oppositions indicates at how many oppositions this object has been observed.


"Root mean square" gives information about the average error of a single position of an orbit in unit of arc seconds. This is an indicator of the exactness of the orbit.


This tells, where the orbits are published. It is usually a page of the MPC (Minor Planet Circular) or an MPEC (Minor Planet Electronic Circular).


Name of the computer calculating the orbits.


Ekliptik
The ecliptic gets its definition from the orbit of the earth around the sun. It is roughly the plane of the solar system in which the planets and most of the comets and minor planets are located.


The Minor Planet Center (MPC) is the official committee of the IAU for comets and minor planets. The institute is located in Cambridge (Massachusetts). In their immense archive, the positional measurements of these objects from all over the world are stored. With this data, the MPC calculates the orbits of the objects.


The astronomical unit (AU) is used for distance measurements in the solar system. One AU is the mean distance between the sun and the earth (149.597.870 km)


The altitude of an object shows the currant distance between the object and the horizon. It is calculated in degrees.


The Azimuth tells you the horizontal position of a star or other object. It is calculated in degrees from the south towards the west.