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Darkness Graphic Document

The Darkness Graphic Document allows you to calculate the beginning and ending times of astronomical darkness over a range of days and depict the results in a graphical report. Specifically, you calculate beginning of astronomical twilight, sun rise, sun set, end of astronomical twilight, moon rise, moon set, moon phase, and astronomical darkness times for the morning and evening.

Information about the Darkness Graphical Report

Darkness Graphic documents are compatible with Darkness Text documents. Both documents perform the same calculations but the Darkness Text document presents the result as tabular text report.

The document contains two adjustable panes. The upper pane allows you to specify how the calculation is done and the lower pane displays the resulting report.

Document Settings Pane

General Tab

Location is used to select a particular location on the earth's surface. A location is required to calculate the times in the report. The location used in a new document is the Favorite Location selected in the Location Manager. Note that when an existing document is opened, it retains the same location that was selected when the document was saved. You may select any location by highlighting its name in the drop down list.

The Legend shows the colors assigned to each type of information depicted in the graph. Change these settings by visiting Graphical Darkness Report Style.

Dates Tab

You may enter dates directly into the Beginning or Ending boxes, or you may use any of the Date Presets. The beginning date must precede or equal the ending date.

The calendars work for dates between January 1, 1753 and December 31, 9999 inclusively. This is a Windows limitation. If you enter a date outside of this range into the year/month/day boxes the associated calendar is disabled. You may use the calendars or the year/month/day boxes to specify dates within the range.

Date Presets

These presets may be used to specify some commonly used beginning and ending dates, and the days to skip value. The default Preset is specified in Preferences | New Documents.

Preset	Beginning Date	Ending Date	Days to Skip
Today	midnight today	11:59 pm (23:59) today	1 day between calculations (1 calculation).
Tomorrow	midnight tomorrow	11:59 pm (23:59) tomorrow	1 day between calculations (1 calculation).
This Week	midnight on Sunday of this week	11:59 pm (23:59) on Saturday of this week	1 day between calculations (1 calculation per day for a total of 7 calculations).
Next Week	midnight on Sunday of next week	11:59 pm (23:59) on Saturday of next week	1 day between calculations (1 calculation per day for a total of 7 calculations).
This Month	midnight on the first day of the present month	11:59 pm (23:59) on the final day of the present month	1 day between calculations (1 calculation per day for a total of 28 to 31 calculations, depending on the present month).
Next Month	midnight on the first day of next month	11:59 pm (23:59) on the final day of next month	1 day between calculations (1 calculation per day for a total of 28 to 31 calculations, depending on next month).
Remainder of the Month	midnight today	11:59 pm (23:59) on the final day of the present month	1 day between calculations (1 calculation per day for a total of 1 to 31 calculations, depending on the present date and month).
This Year	midnight on January 1 of the present year	11:59 pm (23:59) on December 31 of the present year	1 day between calculations (1 calculation per day for a total of 365 or 366 calculations, depending on the present year).
Next Year	midnight on January 1 of the next year	11:59 pm (23:59) on December 31 of the next year	1 day between calculations (1 calculation per day for a total of 365 or 366 calculations, depending on the next year).
Remainder of theYear	midnight today	11:59 pm (23:59) on December 31 of the present year	1 day between calculations (1 calculation per day for a total of 1 to 366 calculations, depending on the present year).

Days to Skip allows you set any frequency of time between calculations from Days to Weeks. You may enter the skip value directly into the Days to Skip box and choose a unit of time from the drop list.

Report Pane

Calculate initiates calculations and ultimately produces a report. The status of the calculation and creation of the report are shown while these tasks are being performed. You can terminate the calculation by pressing the Cancel button in the status box.

Clear allows you to erase report text and graphics. Report text and graphics are automatically erased before a new report is created.

Help allows you to open online help to this page.

A recessed status box appears beside the Help button. It shows the number of days reported for the most recent calculation if a calculation has been performed. If the text in the status box is grayed then the settings in the document have been changed and the report has not been refreshed by Calculate.

Darkness Graphic Report contains the graphical report that results from the most recent calculation. Click here to see a description of the Darkness Graphic report. The report can be scrolled vertically using cursor keys or by clicking the scroll bar.

The report window has a context menu that can be accessed by right-clicking in the window.

▪Preferences

▪Graphical Darkness Report Style

What about?

Some peculiar situations can arise in a darkness document. It is possible to have no sun rise or set, and no moon rise or set. They may be always up or always down during the day. Consider the case of the equinoxes at the poles, for example.

It is common to have no moon rise or set on certain days of the month at any latitude because sun and moon move through the sky at different rates. For example, the moon may rise a few minutes before midnight on a given day, set around noon, and rise again a few minutes after midnight of the following day. The moon never rises during the given day.

You can calculate darkness for up to 65535 days.

You can save the darkness graphic report only to HTML format.

Additional Information:

▪Accuracy of darkness calculations

▪Saving a report to HTML

▪Printing a document

▪Saving a document

▪Setting default values for a new darkness graphic document

▪Darkness Graphic document speed button can be placed on your tool bar so that you can create a document instantly.