Asteroid 4340 Dence

Asteroid 4340 Dence is a main belt asteroid with an estimated diameter of about 10 km. It was discovered on May 04, 1986 by Carolyn S. Shoemaker at Palomar Observatory. The semi-major axis is 2.43 AU, the eccentricity is 0.233 and the inclination is 25.18 degrees.

This asteroid was very frustrating to analyze. Observations were made on 8 nights over a four-week interval during May and June 2008. However, the scatter in the data was relatively large in comparison to the amplitude of variations. Two possible results were found. One with a period of 11.461 hours and another with a period of 15.473 hours. Due to the scatter in the data, either or neither of these results could be correct. More work is needed on this asteroid. The 11.461 hour result is shown below.

Lightcurve results for 4340 Dence.
Derived period 11.461 +/- 0.005 hours. Amplitude 0.2 +/- 0.05 magnitude.

In late 2014 and early 2015 I was able to observe the asteroid again. The five nights of data completely ruled out the earlier results and showed a very clear period of 7.5614 hours. This was almost exactly half of the 15.473 hours that had been suggested in the earlier result.

Lightcurve results for 4340 Dence.
Derived period 7.5614 +/- 0.0001 hours. Amplitude 0.43 +/- 0.05 magnitude.