Opportunity to Confirm an Asteroid’s Moon

Help us find asteroid 146 Lucina's satellite Tuesday morning! In April
1982, an occultation (eclipse of a star) by a probable satellite of
this asteroid was video recorded with the 1-meter telescope at Meudon
Observatory near Paris. The occultation by Lucina itself was
observed in a different path crossing northern Spain. The
observation implies an object at least 6 kilometers across about 1,600 km
from Lucina, as reported in Icarus, Vol. 61, pp. 224-231.

Observers across most of the USA, northern Mexico, Ontario, and southern
Quebec have a chance to make confirmatory observations of the
satellite if they monitor the easily found 8.2-magnitude star SAO 77528,
about 2° east-southeast of Zeta Tauri, for a few minutes just before
9h Universal Time on Tuesday morning, August 21st.

Especially those with video
equipment in most of North America are encouraged to record the star
for a possible quick blink, expected to last about 0.2 second, that
could be caused by the satellite. In addition, observers in
southern Arizona, northern New Mexico, Kansas, northern Missouri,
southern Iowa, northern Illinois, southern Wisconsin, lower
Michigan, central Ontario, southwestern Quebec, and some nearby
areas will have a spectacular occultation by Lucina that will last
almost 5 seconds; visual, video, and CCD observers throughout those
areas are especially encouraged to observe to help us determine the
size and shape of Lucina.

Lucina, a C-class ("carbonaceous")
asteroid, is expected to be about 132 km across. This is one of the
better asteroidal occultations in North America this summer, and the
best until September 20th, when Lucina will occult a 7.9-magnitude star
in a path from central California to northern Minnesota (and give
the West another opportunity to look for the satellite).

For more information and instructions for reporting your observations, see my website:

David W. Dunham

Contributing Editor

Sky & Telescope