Gray Line
The Gray Line tabpage contains a toolkit for all aspects of gray-line operating. It is the most comprehensive Gray Line toolkit available to date.
The base controls are split into three boxes: Date/Time, Location A, and Location B. Let's start with a simple GrayLine display. Set the Date/Time Selector to 'Now', and click the 'GrayLine from Date/Time Selector Value'. The grayline for this instant will be superimposed on the map. Locations aren't involved in that.
Actions
Next, let's try a Map-Click action. Select 'Sunrise for Date' below the map, then click the map at any position. The map will add a Gray Line corresponding to the sunrise at that position, on the Date already set on the Date Selector. Try changing the date by clicking the month, day, or year, and then using the up/down arrows. Click the map again, and a different shaped grayline will be plotted. The sunrise time for that date and position will be set in the Time Selector. A small red marker is added to the click-position, and the short path route from your Home Position will be added.
We can also plot graylines for sunset at a clicked position and a selected date, or solar midnight at a clicked position and a selected date.
Animations
Animations are also available. These are useful to get an idea of how the grayline changes over time. Five different animations are available:
1/ Sunrise for Date - This animation uses the Location A position, and then plots a grayline that advances in 7-day steps. Click the 'Start Animation for Selected Action' button to see the animation. The UTC sunrise-time for each date/position is shown in the Time Selector. An easy way to set a Custom Location is by clicking the map prior to clicking the 'Start Animation for Selected Action' button.
2/ Sunset for Date - This animation also uses the Location A position, and then plots a grayline that advances in 7-day steps. Click the 'Start Animation for Selected Action' button to see the animation. The UTC sunset-time for each date/position is shown in the Time Selector.
3/ Solar Midnight for Date - This animation also uses the Location A position, and then plots a grayline that advances in 7-day steps. Click the 'Start Animation for Selected Action' button to see the animation. The UTC solar midnight-time for each date/position is shown in the Time Selector.
4/ Dates for Time - This animation does not use a Location. It draws a grayline for the time specified in the Time Selector, and then advances the Date in 7-day steps.
5/ Times for Date - This animation also does not use a Location. It draws a grayline for the date specified in the Date Selector, and then advances the Time in 30-minute steps.
Tabular Data
As an alternative to the map, and as a way to produce far more information than a map can show, we can also produce tables for 11 different conditions. Select the desired one using the radio-buttons in the 'Generate Sunrise/Sunset Lists in Tabular Format' box, then click the 'Show in Tables' button.
01/ When Location A is at Sunrise, and Location B is in Darkness, over 1 Year.
02/ When Location A is at Sunset, and Location B is in Darkness, over 1 Year.
03/ Mutual GrayLine for Location A and Location B, over 1 Year.
04/ Mutual Darkness for Location A and Location B, over 1 Year.
05/ Which Countries have Sunrise Or Sunset whilst Location A is in Darkness, on Selected Date?
06/ Which Countries are in Darkness whilst Location A is at Sunrise or Sunset, on Selected Date?
07/ Which Countries have Sunrise Or Sunset whilst Location A is at Sunrise, on Selected Date?
08/ Which Countries have Sunrise Or Sunset whilst Location A is at Sunset, on Selected Date?
09/ World Sunrise/Sunset Times for all Countries, on Selected Date.
10/ All-year Sun Calendar for Location A.
11/ All-year Sun Calendar for Location B.
The results, if there are any, will be displayed in the 'Tables' tabpage. By changing the values for Location A and B, you can explore different grayline conditions, and see how they can help your H.F. operating practises. Times are given in UTC, plus local time for both locations.
Some of the routines are especially useful, and provide information that is hard to group together in any other way. For instance: say you have woken up just before your dawn, and wonder which countries are just about to have a matching grayline path. For an answer, set the Date/Time Selector to 'Now', set Location A to 'Home', and select the 'Which Countries are in Darkness whilst Location A is at Sunrise or Sunset, on Selected Date?'. Click 'Show in Tables', and a list of countries will be produced, with UTC and local times for both ends of the path. By choosing a custom Date, you plan grayline openings for the next contest.
Solar Definitions
Dawn - A point in time when the sun is 6 degrees below the horizon, just before sunrise.
SunRise - The sunrise time at the horizon.
PostRise - A point in time when the sun is 3 degrees above the horizon, just after sunrise.
PreSet - A point in time when the sun is 3 degrees above the horizon, just before sunset.
SunSet - The sunset time at the horizon.
Dusk - A point in time when the sun is 6 degrees below the horizon, just after sunset.
Solar Midnight - This is the time that is opposite to solar noon: it's when the sun is pointing directly below Location A (also called the 'nadir'), and the night is equidistant from dusk and dawn. Solar midnight rarely coincides with midnight on a clock. Solar midnight is dependent on longitude and time of the year rather than on a time zone.
HalfWay - This is the solar midnight at the half-way point between Location A and Location B. ON4UN says that this time can be one of the peak times along that circuit.