CHANGING COLORS

Color

Number Use Default Color

0 Background Gray

1 Astrolabe Plate Red

2 Numerals and Tic Marks White

3 Shading Variable

4 Stars Blue

5 Rule Yellow

6 Ecliptic White

7 Mercury/Messier objects Light Gray

8 Venus/Jupiter stripes White

9 Earth Light Blue

10 Mars/Jupiter red spot Red

11 Saturn Peach

12 Uranus/Jupiter stripes Cyan

13 Neptune Brown

14 Phase shadow Dark Gray

TEXT AND HIGHLIGHTED TEXT

The numbers define the color to be used as the foreground and background colors for normal and highlighted text. They are same colors as defined in color blocks above. Any combination can be chosen.

CHANGING COLORS

Each color is made up of a red, green and blue component. The amount of each color is defined by a number between 0 and 63 with 0,0,0 being black and 63,63,63 being bright white. New colors can be defined by varying the basic color proportions. To change the colors, position the cursor under the R (Red), G (Green) or B (Blue) component and either type in a new number or use the Shift+Big+/- keys to vary the value. Changes are instantly reflected in the color block.

The shaded sky color can be changed when shading is on AND the Sun is above the horizon. The sky color during twilight is calculated depending on the Sun’s altitude and cannot be changed.

Note that some of the planet colors are used in multiple places and that the text screen colors are chosen from the same palette of 16 colors that is used for the astrolabe and planets. If you change one of these colors you will change the text screen colors. Conversely, you can change the text screen colors by changing the planet colors. It is fun to play with the colors.

There are many opportunities to modify the Electric Astrolabe display by manipulating the colors. The default colors have been chosen to maximize contrast in order to make reading the display as easy as possible. However, other combinations create interesting displays. For example, a brass colored background (R=63, G=44, B=0) looks nice with various combinations of colors for the plate and numerals.

If you make the plate lines a medium gray (30 or so) you get an interesting shading effect during twilight as the Sun rises or sets.

Another option is to make the plate color the same as the sky shade (R=36, G=58, B=63) so the altitude/azimuth lines disappear in the daytime. You can also manipulate the colors to highlight the area of

Using The Electric Astrolabe 63 interest such as the Messier objects. A color combination that reduces contrast when shading is in effect is to set the background to a medium gray (R=G=B=30), set the Ecliptic color to a lighter gray (48) and set the rule to lighter gray still (54). This sort of color scheme reduces the sky contrast during daylight hours and makes the night sky stand out. A “starter set” of color combinations is supplied with the Electric Astrolabe.

There is a lot room for experimentation with colors.

PRINTING

It is possible to print both the graphic and text screens on your computer printer using the Print Screen function of DOS or the Windows Clipboard. There are also some excellent screen capture programs available. The results are quite good and the process is easy with a little practice.

You can print the text screens under Windows by copying the screen to the clipboard (Alt+PrintScrn) and then pasting the clipboard into any Windows word processor. You will have to change to a fixed pitch font such as Courier to get the text page columns to line up. You can then edit and print the word processor file.

The Windows Clipboard will capture the VGA graphics screens (but not SVGA!) screen in black and white but the operation seems to depend on the Windows version. Some versions treat the background color as white and all other colors as black. Therefore, the shaded area above the horizon (color 3) comes out completely black. You can draw the astrolabe without the shading color by causing the plate to be redrawn with shading OFF. This can be done in several ways: do a SAVE with shading OFF (X) and then RESTORE, turn shading off and switch to the southern projection and back to the northern projection (Alt+N) or invoke a new city with shading off and return to the current location (=). This format is suitable for copying the astrolabe to the Clipboard and then printing as described above. Windows 98 copies the VGA astrolabe in color to the clipboard.

The Windows clipboard requires the background color to be something other than black (0,0,0) to capture the image in blank and white.

You can print directly to the printer with the DOS GRAPHICS function under DOS. Just start GRAPHICS before you start ASTRO and then use Shift+Print Screen to copy the screen to the printer.

You may have to modify the aspect ratio and colors to get a good printout. The IBM ProPrinter graphics have become “standard” for many screen copy programs. With this technique you will have to change the screen aspect ratio to about 0.831. Other values may be needed for other printers. The print screen program uses various shadings of black to simulate colors. You may find it advantageous to set up a default file for printing that uses the colors and aspect ratio that works best for your printer. For example, you might make everything white except the plate. You can SAVE the current screen, LOAD the print default file, print the screens using Print Screen and then RESTORE. With matrix printers you may be able to get the astrolabe screen and the V text screen on a single page which is very handy for taking outside for casual observing. Laser printers rotate the graphics image so it is larger, thus preventing putting both screens on a single page.

Your printer’s standard character set (sometimes called a code page) must be one that includes the forms design characters in order to get a proper printout of the text screens. This code page goes by various names such as 837 or the PC-8 symbol set. All printers support this code page but you may have to invoke it on your printer if it not the standard one you use.

If you have a laser printer that will print HP Laserjet II data streams you can get good quality prints without modifying the aspect ratio. Just load the DOS graphics print program by keying GRAPHICS LASERJETII under DOS and invoke the graphics screen copy function with Shift+Print Screen. Note that the DOS GRAPHICS function works only for VGA mode. It will not print an SVGA screen.

64 Using The Electric Astrolabe You can use the GRAPHICS function of DOS to print the graphics screens under Windows but you must start both GRAPHICS and the Electric Astrolabe in a DOS session. If you start GRAPHICS under DOS and then start the Electric Astrolabe under Windows, the GRAPHICS function is not recognized.

CUSTOMIZATION

You will want to customize the Electric Astrolabe for your location and color preferences. In order to customize The Electric Astrolabe you will set up all of your color and location preferences and FILE the configuration to ASTRO.EXE. The following steps might be useful in customizing:

1. Put your location (city name, latitude, longitude, time zone) as the first city on the page of city names.

2. Make your location the active city by moving the cursor to the first city and pressing Ctl+Enter..

3. Change your time zone and home zone to the correct values on the Program Control page.

4. Select the color combination you want to use.

5. Make sure the switch settings are the way you want since the switches define which astrolabe components are displayed when the Electric Astrolabe is started. Some people prefer to leave out the ecliptic and objects. Pay particular attention to Manual Mode and Precession since you will probably want them OFF.

6. Add any cities of interest to the list on the cities page.

7. Add any deep space objects of interest to the list of added objects.

8. Make sure ASTRO.EXE is in the File: field. Put the cursor in the ACTION field and press ENTER until you display FILE, then press Ctrl+ENTER to save the startup configuration.

9. You might also want to name the color combination you like the best and save a separate file that describes the overall color combination (e.g. GRAY). This will allow you to continue to experiment with the various display parameters and load previous values.

Of course, the defaults can be changed at any time and you will want to experiment with colors.

Note that under Windows 95 or Windows 98 you must ‘Exit to MS-DOS’ to store the changes in ASTRO.EXE. This is not necessary under Windows XP.

There is an alternative way to customize The Electric Astrolabe under Windows 95/98 that does not require restarting your computer in MS-DOS mode.

You can create a file containing your location and display default and initialize The Electric Astrolabe with this file when you start the program. The following steps outline the procedure:

1. As above, set the defaults you want for latitude, longitude, time zone, colors, etc.

2. Make the first city the active location by moving the cursor to the city name and pressing Ctl+Enter.

3. Go to the Program Control page (C) and type the name of the location you want in the Description:

field. This is the city name that will be used when you start The Electric Astrolabe.

4. FILE the set of defaults using any easy to remember name such as HERE, HOME or any other convenient name.

Using The Electric Astrolabe 65 5. Edit the properties of the shortcut that starts The Electric Astrolabe. Right click on The Electric

Astrolabe icon on your desktop or use Explorer to find the shortcut you use to start The Electric Astrolabe and select the Program tab. Change the “Cmd line:” entry to ASTRO.EXE /F filename (e.g.

ASTRO.EXE /F HERE) and click OK. This will cause The Electric Astrolabe to use your file of default settings whenever it starts. Similarly, if you start The Electric Astrolabe from DOS, use

“>astro /f here” as the command to start the program.