Occultation of HIP 78708 by the Asteroid Ara - Jan 27, 2009

I successfully video recorded this occultation from Cabrillo College Observatory (at the old photometry pedestal) using a Canon ZR 45mc and Kiwi time inserter with PC 164c video camera. The event was low in the southeast, just above the trees on the ridge, 24 degrees altitude. Seeing was poor, temperature was 32F and calm with no clouds. I used the 10" Meade LX200 with Meade f3.3 focal reducer. I was at track 41.282 km north.

Here is a screen capture of the Limovie panel (click to enlarge), showing the target star (the brighter image) and a convenient second star nearby (yellow circle) used for tracking. The target star is listed as a 10 arc second double star, and in fact on many of the frames I could see faintly a star - certainly not the asteroid at magnitude 13.8 and 2 magnitudes below my estimated threshold. The 'second star' in the yellow circle here, is shown in the Hubble GST as magnitude 11.2.

The LiMovie reduction went without problem, and the Occular reduction converged to a solution quite nicely.





Below is the Occular fit to the data.

The noise showed a fairly Gaussian distribution. The final fit to the events, after 100 trials, was

D: 13:37:46.714 +- 0.017 sec

R: 13:37:48.880 +- 0.017 sec

for a duration of 2.167 +- 0.017 sec, showing that I was near the centerline as the predicted maximum event duration was 2 seconds. This suggests a north shift. The IOTA report form is here. The Occular final report as a .jpg is

My Station Coordinates:

W. Long: 121 55 26.63

N. Lat: 36 59 34.42

elev. 210 feet

Track: 41.282 km north.

The observed profile. Note the one visual chord with something apparently wrong. And also note that my own chord (#4) shows that the asteroid is not elliptical but has topography - not unexpected for such a small (62 km predicted) rock with weak self gravity. Maybe it had a traumatic birth? Maybe it was beaten up badly in a scuffle with another asteroid? Click for a larger picture.