4909 Couteau is a main belt asteroid with an estimated diameter of about 15 km. It was discovered on Sep 28, 1949 by M. Laugier at Nice. The semi-major axis is 2.27 AU, the eccentricity is 0.246 and the inclination is 2.41 degrees.
This asteroid was observed on 4 nights nights during August 2014. The results indicated a period of 5.0505 hours and a large amplitude.
With an amplitude in excess of 1 full magnitude, it was possible to see the change in brightness on the screen as the images were obtained. Below is a combination of images obtained on August 18, 2014. 4909 Couteau is the bright trail in the upper right. The variation in brightness of the asteroid is obvious. To the bottom left is the trail of another asteroid, 92267 2000 BK26.
This above image also should contain another object, Comet P/2005 L1 McNaught. It was predicted to be around magnitude 16.8 at tthis time. The location was just a little to the lower left of 4909 Couteau. However there is not the slightest trace of the comet. This just shows the difficulty in predicting the brightness of comet, especially those that have only been observed on one return!!