Comet 9P/Tempel 1 Impact July 2005

The images below are CCD images of the Comet Tempel impact taken on July 3rd from my backyard in Sunnyvale, California. The images are both composites of 10 and 15 second exposures taken over the course of an hour that were combined using software called AIP4WIN. The left image was stacked by matching up the star images so you can see the comet moving (and brightening after impact). The right image was stacked by matching up the comet. You can see how much the images have to be offset near the edges. Unfortunately, I wasn't consistent with the exposure times - all the shots after the impact were 15 seconds long; all the exposures prior to impact were 10 seconds long, and they were not taken at exactly the same intervals. But part of the brightening in the left image is real, though it was not apparent on any given shot at the time.

The images were taken with a Meade LX200 F/6.3 SCT coupled with an SBIG ST-9XE camera. The comet was roughly magnitude 9.0, but these shots were taken when the object was low in the sky, so there is substantial attenuation due to the atmosphere.

I took a series of very short exposures rather than a longer exposure because my telescope was mounted on an alt-azmith mount. This means that I get field rotation for even relatively short exposure times, and more important I can't engage the periodic error correction mode on the scope drive (the later models supposedly do have this feature available in alt-az mode). This was essentially first light for this camera.

You can read more about this impacton the Sky and Telescope web site, the Science News web site or the NASA web site.