Lamberta Results

Three members of BAS attempted the Lamberta Occultation on 12/19/07 along with Paul Maley.  Paul recorded a 9.59 second occultation event from very near the predicted center line, north of Dewey.  John Grismore recorded a 9.644 second occultation event from Dr. Woods’ site west of Ochelata.  Daniel Parrott set up remotely in Caney, but was unable to observe the occultation due to equipment problems, and Gary Nealis attempted the occultation from Bartlesville, but was clouded out.

Grismore/Woods Observation

Meade LX200R 8" SCT                               Ochelata, OK
f/3.3 Focal Reducer                                    (Woods' Observing Site)
Watec 902H2 Ultimate video camera        D   05:11:33.351UT +/-  .02s
KIWI-2 / KIWI-OSD gps time inserter        R   05:11:42.995 UT +/-  .02s
Sony DCR-HC42 miniDV camcorder        Duration: 9.644 +/-  .02s 
The above graph shows the target star light curve in blue and the light curve of a comparison star in the same field in yellow.  The effects of high clouds drifting across the field can be seen in the cyclic variation of the light curves before the event and the steady decline in intensity after the event.  The occultation event is obvious in the center of the graph where the target star’s light curve steps abruptly to very low levels and remains there for nearly 290 video frames, then steps abruptly back to pre-occultation levels.  During the event the comparison star, although dimming due to clouds, does not show the same step event.
 
Video was imported from the camcorder into iMovie.  A small segment centered on the suspected event was exported as an avi file, stacked with a 3 frame running average in Registax and then analyzed by LiMovie to produce the light curves.  Event times were determined from video inserted GPS times.

Preliminary Asteroid Profile Results
Brad Timerson has produced a preliminary best fit estimate of the cross section profile of asteroid Lamberta.  The link to the profile plot is:
 
http://www.asteroidoccultation.com/observations/Results/Data2007/20071220_187_LambertaProfile1.png