Events like this can be timed by observers using small telescopes or recorded using an inexpensive video camera aimed into a telescope. David Dunham, president of IOTA, explains these techniques in the article "Camcorder Timing Tips." A map showing the approximate path of the event, as well as a list of other occultations by asteroids in 2003, can be found in Dunham's article "Planetary Occultations for 2003." In the days leading up to an event, more detailed information is often posted in IOTA's asteroid section and sent out in a Sky & Telescope AstroAlert issued by Dunham.
c) Geminorum, blocking its light for up to 7 seconds. David W. Dunham of the International Occultation Timing Association expects this event to be seen in a path from the southern tip of Greenland to the Great Lakes of North America. The path goes north of the populous banks of the St. Lawrence River. The star will be covered near 5:22 Universal Time on September 25th.