Comet Tempel 1 and Deep Impact

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Desert Moon Observatory images Comet Tempel 1 during the Deep Impact Event.

Desert Moon Observatory took a series of images of Tempel 1 starting about 5 minutes before impact with a Meade 12-inch LX-200 and Apogee AP-7b. Each was 50 seconds, with a 10-second download between. The images were reduced with Herbert Raab's excellent Astrometrica astrometry program with an aperture with a radius of 17 pixels (27.2 arc seconds). Astrometrica uses an annulus around the aperture for background levels and the zero-point was set by at least 12 other stars in the field. Resulting magnitudes (with only one decimal place) were plotted with Excel and plotted below. The impact occurred during the red data point.

The measured comet magnitude is plotted on the Y-axis, and the day and fractions of a day on the x-axis. Since the data is of limited photometric accuracy, measurements were limited to only one decimal place, which accounts for the jumps occurring in 0.1 magnitude units. From what examination of the images, there were some clouds or other obstructions in the field blocking some of the light from the comet. There is also a street light that threw some stray light into the telescope, further limiting the quality of the measurements. The brightening portrayed below were not apparent in the live images, and by the end of the sequence the comet was only about 8-degrees up, not exactly what would qualify as a "photometric" situation.

Comet Tempel 1 just before impact (stack and shift of 5 frames x 50 seconds each). Both this and the one to the right are to the same scale.

Comet Tempel 1 approximately 52 minutes after the Deep Impact impactor strike. (stack and shift of 9 frames x 50 seconds each).



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Last updated 2005-07-05.