What is OccuWeather?

OccuWeather is a website for tracking cloud cover for occultations.

So what's an occultation?

In astronomy, an occultation is simply when one body covers another, usually as seen from the Earth. For example, a total solar eclipse -- when the Moon covers the Sun -- is an occultation. Other objects have occultations as well, such as an asteroid covering a star at night. And like a total solar eclipse, an occultation is only visible at a specific time -- and only from a specific path on Earth.

Timed observations of these events give us details about the asteroid -- orbit refinements, size, shape, whether it has moons. And this information is often more accurate than what we get from direct telescope images -- even from large observatories and space telescopes. Yet these events can be seen by amateurs with mid-size telescopes that fit in a car. In fact, there is an organization of amateur astronomers dedicated to observing them -- IOTA. Occultations are so useful that several NASA spacecraft missions have used them in mission planning.

Why a special weather site for this?

Like for eclipses, astronomers may travel to the paths of occultations to observe them. Since there are many asteroids and stars, there are many occultations -- dozens a month if one is motivated and mobile. So checking the weather to find a clear spot -- within the path -- is a common task. And while there are separate occultation and weather websites, this site combines them to aid the mobile observer.

OccuWeather does this by overlaying event paths directly atop live weather imagery, which has several benefits:

• No switching and mentally translating between two different maps -- event path and weather -- when looking for a clear area.
• Weather maps stay focused on event time -- so they are always on the correct, up-to-date forecast (when available) on revisits.
• Viewing wide-area imagery instead of a few sites' point forecasts lets highly mobile observers check a broad path.
• Multiple weather providers are available under one consistent interface.

See the Events page for a list of currently plotted events.

Acknowledgements

Thanks to Hristo Pavlov, creator of the OccultWatcher site and software, for valuable insight and assistance.

OccuWeather displays weather imagery from the Canadian Meteorological Centre, Wetterzentrale, the US National Weather Service, and Cloud Free Night. Thanks to Robert Dahni of Cloud Free Night for providing imagery and assistance in displaying it on this site.

Geocoding services are provided by OpenStreetMap.

Thanks to the members of IOTA and others who have provided useful testing and feedback.

OccuWeather is an ongoing project developed and maintained by Kai Getrost, who can be contacted via email to info at this site's domain.