KML controls

Several buttons on the prediction page are associated with the KML (prediction path):

The globe button (or pressing k) toggles whether the KML (occultation prediction) overlay is shown on the map or not. Turning it off can make the underlying weather more visible when the KML lines are close together.

The letter-A button (or pressing l / "el") toggles whether labels for KML points are shown or not.

The inward-pointing-arrows button (or pressing i) toggles the size of KML icons. By default they are shown normal size, but toggling the button makes them smaller, revealing more of the surrounding weather imagery.

Map features

The overall KML name and description are shown below the GUI controls (below the imagery timestamps). Hovering or clicking on a map KML element (e.g. a line or icon/point) highlights it on the map, and shows its details -- layer name/description and placemark name/description -- in the below-GUI KML info area. Clicking anywhere else (e.g. map or page background) un-highlights the currently-highlighted KML element (if any).

A point placemark, when highlighted, also has some location info shown in the KML info area: its latitude/longitude; a Google link to open it in Google Maps in a new tab; and an LPM link to open it at lightpollutionmap.info. Both maps are the same scale and center location (once sidebars are closed), so they can be "blink compared" by toggling their browser tabs back and forth.

The KML, if available, may be downloaded via the settings dialog (see the Settings help page).

Scratch placemarks

Note: This feature is still in development, may not be enabled on all prediction pages, may not work correctly, and may change or be removed in the future.

If enabled, scratch placemarks may be added to the map with these buttons:

The pin button (or pressing p) toggles add-placemark mode on/off: when on, clicking on the map adds a scratch placemark at that location. (The pointer cursor changes to a cross when hovering over the map when this mode is active.) Once a placemark is added (or Esc or p is pressed), the mode turns off.

The default description for scratch placemarks is additional location-specific information. This may include its estimated event midtime; star altitude and direction; Sun altitude; and Moon altitude, direction, phase, and separation from the star. The estimated event midtime is for the location only if the box says Est. location event midtime; otherwise geocentric time (and Est. geocentric event midtime) may be given. Note that location event midtimes are KML-derived estimates, and thus become more inaccurate the farther the location is from the centerline. Some information may not be available if not derivable from KML or Occult XML.

The name, description, and latitude/longitude of scratch placemarks are editable in the below-GUI KML info area; this is indicated by their text boxes having a gray background, unlike KML placemarks which are not editable (and hence white background). Click on a box to edit it.

For editing latitude/longitude, several formats are accepted:

• D.DDD, D.DDD numeric decimal latitude, longitude
• A Plus Code
• A text place name, such as Boulder CO

If the location is recognized, the description (star altitude etc.) will change to reflect the new location. If the new location is not visible in the current map region, the map might change to a region where it is visible.

Since scratch placemarks are editable, they are deletable as well; the trash icon will delete the placemark.

Note that scratch placemarks are not currently saved in any way; even reloading the page will lose them.

Clicking the circle button will add a scratch placemark that tracks the user's current location. This may pop up a browser dialog asking for permission to share your location with this site. If permission is (or has been) refused, the button is disabled. (Click the lock icon in the browser URL bar if so, to find an option to reset/re-enable permission.) The button may turn yellow briefly while the app waits for initial position information. It turns blue when location tracking is fully active and plotted.

The user's current location is shown with a red circle on the map, and will be updated occasionally. When an update shows it is not visible on the current map, the map may change to a region where it is visible. Star alitude etc. information is shown as for other scratch placemarks. However, the current-location placemark is not editable, since it is auto-updated.