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Sky Navigator

Download SkyNavigator.zip (1.6 MB) for Windows


Example screen shot of a couple of SkyNavigator functions


Description & Help:

Chapter:

1 START
2 EDIT
2.1 EDIT DATABASE
3 INPUT
3.1 LOCATION
3.2 DATE & TIME
4 OPTIONS
4.1 SCREEN RESOLUTION
5 TOOLS
5.1 VIEW DATABASE & TRACKING
5.2 EPHEMERIS DATA
5.3 SOLAR SYSTEM VIEW
5.4 JUPITER MOONS
5.5 SELECT COMET/ASTEROID
6 STAR MAP
6.1 EQUATORIAL MERKATOR PROJECTION
6.2 HORIZONTAL MERKATOR PROJECTION
6.3 STAR MAP VIEW OPTIONS
6.4 OBJECT INFORMATION
6.5 FIND OBJECT



Installation:
There is no installation necessary. Just un-compress the ZIP file where ever you want and start SkyNavigator.exe.

SkyNavigator License:
Copyright (c) 1995-2006 by Stephan Hotto. All rights reserved.

This Software is provided "as-is", without any express or implied warranty.
In no event will the author be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software except for commercial use.


1 START
After starting "skynav.exe" you will be asked for your location. There are a couple of locations already available which you can extend in the location.db by using the "EDIT DATABASE" function.

In a next step SkyNav will ask you for date and time as well as the daylight saving status.
You can simply get your computer system time by clicking the button "GET SYSTEM-TIME".

Both Location as well as date and time can be changed when ever you want by using the functions grouped under the "Input" menu.


2 EDIT

2.1 EDIT DATABASE:
The database editor allows you to edit any database provided with SkyNavigator:

location.db A list of locations which are selectable by "Input -> LOCATION"
ast.db Asteroids (Year 2000)
comets.db Periodical Comets (Year 2000)
messier.db All Messier objects from M1-M110
ngc.db NGC Objects like Galaxis (Year 2000)
pulsar.db A couple of pulsars (rotating neutron stars)
sao.db SAO Catalog (Year 2000)
ybs.db Yale bright star catalog (Year 2000)


An empty line within the database always marks the point until SkyNavigator reads the values.
To avoid that you accidentally destroy important data SkyNavigator creates backup copies before it changes the original database by using the following naming: "./database/DBNAME.bak"


3 INPUT

3.1 LOCATION:
That input window enables you to give your position in latitude (N/S) and longitude (W/E).
To allow SkyNavigator to calculated the correct star time it needs your time zone.
Furthermore, you have a list of pre-defined locations which you can edit within the location database "./database/location.db" by using the function "Edit -> EDIT DATABASE"
Please keep in mind that positions south or east have to have negative values.


3.2 DATE & TIME:
This is a very important input window with the following key functions:

DATE Date in the format dd.mm.yyyy
TIME Time in 24h format
ZONE Your time zone in relation to GMT
DAYLIGHT SAVING If this box is ticked then the program uses summer time
GET SYSTEM-TIME Allows you to take the current computer time instead of typing it in
SYNC. ON S-TIME If this box is ticked then SkyNavigator calculates the current local star time by synchronizing continously with the computer time. This allows you to update any window permanently under the pre-condition that in those windows the SYNCHRONIZE tick box is activated.
ANIM. STEP This entry field accepts the animation step width in fractions of days (e.g. 1.5 or -3). Please see also ANIMATION tick box
ANIMATION This tick box activates the animation mode which allows the animation of each STAR MAP the DATABASE TRACKING, SOLARSYSTEM VIEW and JUPITER MOONS. Please also activate in those windows the SYNCHRONIZE tick box to show the animation. The animation speed is dependent on the amount of objects you have in an active view.



4 OPTIONS

4.1 SCREEN RESOLUTION
Define the screen resolution usable for SkyNavigator
- 800x600
- 1024x768

This influences the window size for the "SOLAR SYSTEM VIEW" and the "JUPITER MOONS"


5 TOOLS

5.1 VIEW DATABASE & TRACKING
Within the DATABASE window you are able to select a database and an object within that database to calculate the associated position in azimut and altitude.
The EPH tick box is special because here SkyNavigator calculates also the right ascension and declination of the planets, moon and the sun.
Furthermore, you get the rise, transit and set times of the selected object.
A "+" sign indicates that the object is for the current date always above the horizont whereas a "-" shows that it will stay below the horizont.

The "SYNCHRONIZE" tick box activates the synchronization of the view with the DATE/TIME window to allow an animation or to synchronize with the computer time.
As a pre-condition either the "SYNC. ON S_TIME" or the "ANIMATION" tick box of the DATE/TIME window has to be activated.


5.2 EPHEMERIS DATA:
By opening this window SkyNavigator calculates the ephemeris data for the planets, moon and sun.
Furthermore, if you have selected an asteroid or comet by using the menu "Tools -> SELECT COMET/ASTEROID" then this selection will be included in the ephemeris data.

Please use "Edit -> Update" to refresh the view.

Use "Edit -> Save" to save the ephemeris data in the file "eph.txt" within the home directory of SkyNavigator.


5.3 SOLAR SYSTEM VIEW:
This function provides a top and side view of the solar system.

Magnify the view by using the zoom buttons (<>).

The tick boxes have the following functions:

NAMES Activate or deactivate the object names
TRACK Draw the object path to see the Keppler tracks
SYNCHRONIZE Activates the synchronization with the DATE/TIME menu as described above.


The UPDATE button refreshes the view after changing the date or time manually.

The marks show the starting points of the seasons:

SP Spring
SU Summer
AU Autumn
WI Winter



5.4 JUPITER MOONS:
This view represents the positions of the Jupiter moons by showing a top and side view.
The functions are the same as explained in the SOLAR SYSTEM VIEW (Chapter 5.3).

Only the main moons are represented:
- Io
- Europa
- Ganemeyd
- Kallisto


5.5 SELECT COMET/ASTEROID:
Here you can select comets or asteroids out of the databases ./database/comets.db and ./database/ast.db. Please refere to chapter 2.1 to get more information regarding the editing of databases.
Please keep in mind that the calculation routine needs an excentricity below 1.0.

Double click an object in the list to calculate the position in distance to the earth (AE),Right Ascension/Declination and Azimut/Altitude.
Furthermore, SkyNavigator calculates the magnitude.

The "SYNCHRONIZE" tick box activates the synchronization of the view with the DATE/TIME window to allow an animation or to synchronize with the computer time.
As a pre-condition either the "SYNC. ON S_TIME" or the "ANIMATION" tick box of the DATE/TIME window has to be activated.

Activate the "COMPUTE" tick box if you want to get the comet or asteroid also calculated within the following views:
- EPHEMERIS DATA
- SOLARSYSTEM VIEW
- EQUATORIAL MERKATOR PROJECTION
- HORIZONTAL MERKATOR PROJECTION


6 STAR MAP

6.1 EQUATORIAL MERKATOR PROJECTION:
This is a Merkator map showing the object coordinates in right ascension and declination.
If you click once on an object then the map shows the coordinates of that point in hours, minutes and seconds for the right ascension and in degrees, minutes and seconds for the declination.

By clicking the "UPDATE" button the map will be re-freshed (e.g. after a time change).

The "SYNCHRONIZE" tick box activates the synchronization of the view with the DATE/TIME window to allow an animation or to synchronize with the computer time.
As a pre-condition either the "SYNC. ON S_TIME" or the "ANIMATION" tick box of the DATE/TIME window has to be activated.

You can zoom into dedicated areas of the map by a simple double click of the left mouse button. The current mouse position marks the zoom center. Use a right button double click to zoom out. The zoom factor is always 2^n with a max of 512.
Simply click on the "RESET ZOOM" button to set the zoom factor back to 1.
The function keys F1 to F10 allow a direct zoom jump. Hit a function key after clicking once in the area you want to zoom in:
f1 = 2^0 = 1
f2 = 2^1 = 2
f10 = 2^9 = 512

By clicking once near an object and using the "Starmap -> OBJECT INFORMATION" function (please refer to chapter 6.4) you will get a couple of object data like name, magnitude, right ascension/declination and azimut/altitude.

By using the function "Star Map -> STAR MAP VIEW OPTIONS" (see also chapter 6.3) you're able to define what you want to see in the current star map.


6.2 HORIZONTAL MERKATOR PROJECTION:
This is a Merkator map showing the objects position in azimut and altitude dependend on Date/Time and your position as given in the LOCATION window.
Each object with a positive altitude should be visible in case of a perfect horizont.

The view is limited to the planets, sun, moon, comets/asteroids (if COMPUTE within the window "Tools -> SELECT COMETS/ASTEROIDS" is enabled) and SAO as well as Messier objects. NGC, YBS and Pulsars are excluded.
Furthermore, the function "Starmap -> OBJECT INFORMATION" is not supported in this view.
Nevertheless, you can still use the "Starmap -> STARMAP VIEW OPTION" function to define what will be visible in the current view.

The zoom function is limited to magnification by a double click on the left mouse button.
Use the "RESET ZOOM" button to reset the zoom factor back to 1.

The "SYNCHRONIZE" tick box activates the synchronization of the view with the DATE/TIME window to allow an animation or to synchronize with the computer time.
As a pre-condition either the "SYNC. ON S_TIME" or the "ANIMATION" tick box of the DATE/TIME window has to be activated.


6.3 STAR MAP VIEW OPTIONS:
By using this window you can define what objects are visible within the star maps:

Magnitude limit Define visibility between mag -3 to mag 20. The map shows only those objects brighter then the limit you set.
SOLAR SYSTEM Show the planets, sun, moon and comet/asteroid
MOON Switch the Moon on/off
SAO Show SAO catalog objects
MESSIER Show the Messier objects
NGC Show objects from the NGC catalog
YBS Present objects out of the Yale bright star catalog
PULSARS Draw a couple of pulsars
SOL. SYS. NAMES Enable the naming for solar system objects
OBJECT NAMES Enable the naming for all shown objects
ECLIPTIC Switch the ecliptic line on or off



6.4 OBJECT INFORMATION:
If you're using the equatorial star map (Chapter 6.1) then the object information window provides you detailed data about each object you clicked once.
The window can be opend by calling the function "Starmap -> OBJECT INFORMATION" or by using the key combination Ctrl+i.

The workflow to get the information is quite simple:
- Click once near to the object where you want to get the data for
- Hit the "SHOW DATA" button of the "OBJECT INFORMATION" window or press Ctrl+i
- After clicking near to a new object re-fresh the data by using Ctrl+i

The following data are available:

- OBJECT Object name
- NUMBER Object catalog number
- MAG Magnitude (Brightness)
- DB Object database
- RA Right Ascension
- DE Declination
- AZ Azimut (Depend on Time/Date/Position)
- AL Altitude (Depend on Time/Date/Position)
- RISE When the object passes the horizont during rise
- TRANSIT When the object passes the highest position above the horizont
- SET When the object passes the horizont during set



6.5 FIND OBJECT:
The "Star Map -> FIND OBJECT" function is limited to the equatorial star map.

Workflow:
- Select the database where the object you're looking for is in
- Type the objects name in the "OBJECT" entry field and hit . If you keep the field empty then the list shows all objects within the selected database.
- All objects shown by the list are marked within the star map by circling them with a light blue colored mark
- If you double click an object within the list then it will be marked with a magenta colored circle. Furthermore, in case the star map was zoomed the object will be centered within the middle of the current view.


About:

Program: SkyNavigator
Author: Stephan Hotto (Germany/Wuppertal)
Version: 2.02 / 08.04.2006 (v1.0 - 29.08.95; v2.01 - 21.11.98)

SkyNavigator License:
Copyright (c) 1995-2006 by Stephan Hotto. All rights reserved.

This Software is provided "as-is", without any express or implied warranty.
In no event will the author be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software except for commercial use.
The program is provided without license fee.

Overview:
SkyNavigator has been written in TCL/TK which is an interpreter programming language developed by John K. Ousterhout.
The on hand Windows version has been wraped by using the program freeWrap by Dennis R. LaBelle.

Algorithm:
The astronomical algorithm used within SkyNavigator are mainly derived from the book:

Jean Meeus
Astronomical Algorithm
2. Edition

  • Planet position calculation: VSOP87
  • Pluto position calculation: Theory by Goffin, Meeus and Steyaert
  • Moon position calculation: Moon theory ELP-2000/82 by Chapront
  • Jupiter moons: E2-Theory of the moons by Lieske and the enhancement E2x3


The databases have been populated in 1995 out of the following sources:
YBS: ftp://adc.gsfc.nasa.gov/pub/adc/archives/catalogs/5/5050
PULSARS: ftp://pulsars.princeton.edu/pub/catalog/ascat1.dat
NGC: SAGUARO ASTRONOMY CLUB DATABASE, VERSION 6.0
Asteroids: ftp://ftp.lowell.edu/pub/elgb/astorb.dat.gz