Predicted Asteroidal Occultations


The Definitive Site For Asteroidal Occultations In The UK

(Dedicated to the memory of a great friend and astronomer from France, Raymond Dusser, who encouraged me and gave me much advice as I started out in this branch of Astronomy)
Jon Harper

The following monthly information has been produced using data (astorb.dat) supplied by Ted Bowell’s office, at the Lowell observatory in the USA. It is downloaded on a monthly basis, so the data used for any complete month was downloaded on the 15th of the previous month. The predictions themselves, and the path charts, are generated using the excellent WinOccult software (v 3.1.6) produced by David Herald using the Hipparcos, Tycho and UCAC2 star catalogues.

For the UK predictions which follow, I have used the following criteria:


DISTANCE from Scarborough (central in mainland Britain)
Lat: N 54° 16′ 30.4″ Lon W 00° 25′ 05.5″ (WGS84)
<800 km
DIAMETER of asteroid >10 km
MAGNITUDE of target star <12
DURATION of occultation at centre line >1.5 seconds


Please note that astrometry for these small objects is not always as precise as we would like, and there is always some uncertainty in the path. Details here are taken from information available at the time of making the predictions. I have given each path a recommended error margin based on the current information available for any asteroid’s orbital elements and the celestial co-ordinates of the target prior to the predicted occultation. Please note that if a particular event is of interest to you, please always check for updates, which are often made available a few days before the expected occultation.

Updates may be found on the following sites:


Steve Preston’s
Jean Schwaenen’s EAON


Report forms and examples of how to complete these may be viewed and downloaded from the Euraster website maintained by Eric Frappa, where you will also find many valuable links and further occultation predictions for France and adjacent countries, including the UK. Eric’s EURASTER site is:

Report forms and other very useful information can be obtained at the EAON (European Asteroidal Occultation Network) web address given above.

There is a most fantastic program now available called Occult Watcher. It’s freeware that you can install on your PC, which will give you the most up to date predictions of asteroidal occultations for your site. The program links directly to Steve Preston’s predictions, and notifies you, giving great details about where you are in relation to each event. You can even bring up hybrid maps from Google Earth showing the predicted path, centre lines, and probability lines. Download it — you’ll find it absolutely teriffic! To find out more about Occult Watcher, and to download a copy, go to:

Please email for a list of asteroidal occultations for your location –


The maps show the predicted path of each asteroidal occultation event The small inset star chart, which shows a 2° X 2° area of sky, is included for the sole purpose of showing you the position of the target in relation to neighbouring field stars. If you click anywhere on this small inset star map, a much larger and more useful version of this 2° by 2° star chart will appear with all the SAO stars labelled for you to print out if you wish. On this you will find equatorial co-ordinates at the sides of the chart, and two circles centred on the target, which have diameters of 0.5° (the average diameter of the Moon’s disc) and 2.0° respectively. These charts were generated using “Guide 8” software.


All asteroidal occultation observers should subscribe to the PLANOCCULT mailing list, a central place where information and results are shared with fellow observers across Europe, and where you will be informed of updated predictions. To subscribe, please send an e-mail to either Pierre Vingerhoets or Jan Van Gestel.