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About the PackageInstallation and Notebooks

1.1 Loading and Setup

Once you have installed the package, it is a simple matter to load it into Mathematica.

Loading the package.

This loads the package into Mathematica.

In[1]:=<<Astronomer`HomeSite`

Astronomer is Copyright (c) 1997 Stellar Software

Depending on your computer, it may take a minute or so to load if you are using Mathematica Version 2. Scientific Astronomer will take less than ten seconds to load using Mathematica Version 3, however.

Site Location

If you have not already edited the HomeSite.m file with your site details, then you need to use SetLocation to define your geographic longitude, latitude, and time zone.

Setting your site location.

This is the setup for Melbourne, Australia during daylight-saving time.

In[2]:=SetLocation[GeoLongitude -> 145.0*Degree,
GeoLatitude -> -37.8*Degree,
GeoAltitude -> 0.0*KiloMeter,
TimeZone -> 11];

You can put any SetLocation setting into your HomeSite.m file to avoid having to enter it every session. Typically you can use the option setting TimeZone :> TimeZone[] to dynamically compute your time zone. Throughout this user's guide, the TimeZone option is set to 11, which is appropriate for summertime in Melbourne, Australia. It is very important that you use the correct time zone for your own location, as some functions will give inappropriate results otherwise. In particular, be careful that daylight-saving time is taken into account. When daylight saving is in effect over summer, the value returned by TimeZone[] should be one hour greater than normal. Thus, the normal time zone values for the Pacific, Central, and Eastern zones of the United States are -8, -6, and -5, respectively; but for a period within April through October, the values are -7, -5, and -4, respectively.

Note that the sign of the option GeoLongitude is such that positive is east and negative is west. Thus, the geographic longitude of Champaign, Illinois is -88.2 degrees, a negative number because it is west of Greenwich.

You can rename the HomeSite.m file, if you wish. For example, you might want to call it NewYork.m, and configure it for the geographic location of New York. In that case, you can start Scientific Astronomer by typing <<Astronomer`NewYork`. Similarly, you can create other site files, such as London.m or Tokyo.m.

Degree Character

The degree symbol, which is used in the output from Ephemeris and other functions, might not print or display correctly if you are running Scientific Astronomer under a version of Mathematica earlier than 3.0. Some computer systems do not have an appropriate character available, and in such cases you need to set the variable $DegreeCharacter to something tolerable to your system.

Although Scientific Astronomer tries to figure out the correct character, it may become confused if you are running a remote kernel. If your front end is a Unix machine running X Windows or a PC running Windows, you may need to use character 176, that is, $DegreeCharacter = FromCharacterCode[176]. If your front end is a Macintosh, you may need to use character 161, that is, $DegreeCharacter = FromCharacterCode[161]. If all else fails, you can set the variable to the character "^", that is, $DegreeCharacter = "^".

Under Mathematica Version 3.0 or later, $DegreeCharacter is always correctly set for you.

Font Names and Sizes

Labeling of star charts and other graphical output is mostly done with the default font "Helvetica". If you are not satisfied with that font, change it by setting the variable $DefaultFontName to another font name, such as "Arial", "Times-Italic", or "Courier", for instance.

Adjusting sizes of fonts, points, and lines.

Similarly, if you prefer another size of labeling on your monitor or printer, you can set the variable $DefaultFontScale to a scale factor other than the default 1. To increase point sizes and line thicknesses, use the variables $PointSizeScale and $ThicknessScale. On a PC running Windows you will typically need to set $PointSizeScale = 2, but your screen resolution will determine whether this is actually an improvement.

These changes can be made globally and put in the HomeSite.m file if needed.

Note that although you can use $DefaultFontScale to adjust some font sizes used in the package, you will normally use the TextStyle option for this.

Extra Stars

By default, a small number of stars are built directly into the package. These stars are enough to allow all the Scientific Astronomer features to work. You need to load more stars if you require more detailed star charts.

Loading extra stars and objects.

This loads 3,000 extra stars. Similarly, you can load a file containing 9,000 extra stars.

In[3]:=<<Astronomer`Star3000`

One disadvantage to loading extra stars is that it potentially causes some of the star chart functions to slow down, especially on the first call.

The default setup, therefore, includes only the brightest 300 stars, which are more than enough to allow basic constellation identification. The default setup includes all the stars down to magnitude 3.5 and several additional ones.

Once Star3000.m has been loaded, all the 3,000 naked-eye visible stars down to magnitude 5.5 are used. Similarly, with Star9000.m loaded, all the 9,000 binocular visible stars down to magnitude 7.5 are used.

Stars represent only a part of what is in the universe; many nonstellar objects, such as galaxies, nebulae, and clusters are also present. Some well-known objects, such as the Andromeda Galaxy and the Pleiades star cluster, are already built into Scientific Astronomer, and it is possible to access many more by loading the DeepSky.m package.

This loads extra deep sky objects.

In[4]:=<<Astronomer`DeepSky`

See the corresponding DeepSky.nb notebook for a discussion on how to access and work with deep sky objects.

About the PackageInstallation and Notebooks



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