0406_240_29651_MapNAfrom wikipedia.org
An occultation occurs when an apparently larger body passes in front of an apparently smaller one. A transit occurs when an apparently smaller body passes in front of an apparently larger one. In the combined case where the smaller body regularly transits the larger object, an occultation is also termed a secondary eclipse.

We participate in observing occultations. With a medium size telescope, a very good time source, a good knowledge of the sky so you can point it at the correct place, you can help contribute to science in a really meaningful way.

Typically we observe occultation of stars by an asteroid. With many observers spread out along and across the predicted path of the shadow on the ground, we can help determine sizes or at least limits of size of the object. That combined with visual observations of the brightness, one can tell more about the composition of the object as well.

  • Grazing events in North America: http://www.timerson.net/IOTA/
  • International Occultation and Timing Association http://www.occultations.org/
  • http://www.asteroidoccultation.com/
  • There is software that you can download and run from your own computer as well:

    The upshot of all of this is, there will be an occultation in our ground track tomorrow, Saturday April 6th, 2013.
    from around 04:42 onward for up to maybe 10 minutes max.

    Event Date/Time Rank Asteroid Star Visibility dM D A Details
    06 Apr/08:46 UT 75 (240) Vanadis mag 13.7 2UCAC 27674670 mag 12.0 NE USA, Canada 1.9m 8.6s 26° [Feb 09 08:14]

    dM D A
    This column gives the magnitude drop (deltaM), the duration of the event (in seconds), and the maximum altitude of the star during the event. Note that this is the maximum altitude of the star and the star’s altitude will probably be lower at your location.

    More detailed info can be found here:

    Updated: 2013 April 09
    Kim observed and timed the event! Reports went in.
    Kevin did not see anything 🙁