Input User Constants

On this page you can review and modify data pertaining to observing site latitude, longitude, and date/time of observation. License number will be entered through here upon registration. User entered and derived values are highlighted in green with explanatory notes below. Maintaining the proper constants is important because they are used as default values throughout the Astro Function examples and Astro Methods. They will also be usable in your own worksheets along with the Astro Functions if you follow the directions under Usage Notes.

The design of this page was driven by the need to allow users of Mathcad Explorer to save and retrieve this data. This is accomplished through the use of comma delimited data files (".dat") and read/write Mathcad components. The data entry pages can be reached by clicking the Modify buttons next to each user constant displayed below. To ensure that data is written out: scroll down to bottom of each page and click the export component. On return to this page you should see an update. If not just reload the page. If you have problems, read the comments at the top of Read User Constants from File.

Location Data
Longitude and latitude for your observing site can be found by: GPS receiver, electronic road atlas or measuring off a USGS chart at your local library. General coordinates for your town can be found on the Internet or listed in a reference work available at your local library.

Time Data
Determination of Universal Time and date can be found on the Common Amateur Astronomy Terms page.

License Registration Number

Observing Site Location

Latitude

The uLATMAT variable contains a formatted matrix of the user's latitude position. The matrix and its longitude partner that follow are for display purposes and NOT used as a function arguments. The bottom row of the matrix lists the variable names that store each of the degree, minute and second of arc values found in the middle row: uLATDeg, uLATMin and uLATSec. Those three variables are used as function arguments.

uLAT is derived from the above data as the decimal form of latitude. It is available for use in the Astro Methods and any sheet that references this page. Because of the order of the references used in this book the variable is not available for use in the Astro Functions examples.

Longitude

The longitude counterpart of the above is displayed in the uLONMat matrix. Its bottom row contains the variable names of the degree, minute and second components available for use as function arguments: uLONGDeg, uLONGMin, uLONGSec. Values are positive West. Eastern longitudes must have a negative sign on each component.

Longitude in decimal form -- uLONG is created from the above variables. This derived value is not available in the Astro Functions examples.

UT Date and Time of Observation

Date

uDATEMat contains the date display matrix. The function-argument ready year, month and day are listed in the last row: uYR, uMTH and uDAY. The date must be that at the Universal Time displayed in the next section -- be sure to make time zone corrections.

Universal Time

Universal Time (24-hour system) of observation is displayed in the uTIMEMat matrix. Function-usable arguments for hour, minute and second are: uHR, uMIN and uSEC.

Julian Day Number

Julian day number variable -- uJD -- is derived from the date and time above. This variable is not available in the Astro Functions examples.