New Optical Search:
Different Telescope,
Same Small Comets

Part 2

The images for two small comet sightings obtained during the IRO search are shown on Plate 1, taken on January 20, 1999, and Plate 2, taken on February 16,1999. The large streaks seen in these images are star trails; these are longer than they normally would be due to the motion of the telescope which attempted to track the small comets across the sky. Note that the small comet streaks, in the yellow boxes, are not parallel to the star trails.

IRO Plate 1

Plate 1

The trails of both relatively bright and dim stars due to the motion of the telescope's field of view are distributed across the image. The trials of a small comet as acquired in the two trail search mode is indicated by the yellow box in the upper left hand corner of the image. Note that the small comet trails are not single pixel events.

IRO Plate 2
Plate 2

This image was obtained during the three trail search mode. The left hand member of the three trail set is slightly out of line with the two trails to the right. This displacement is due to the effects of motor drives and wind motion on the telescope's field of view. These effects are also seen in the star trails.

Viewers may think they see other small comet trails in the images, but the identification of valid trails must be evaluated quantitatively since visual impressions can be misleading. Real small comet events have a signal-to-noise ratio of 6 or better.

Part 1
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