While looking at Johnny Horne's recent image of the Horsehead Nebula (September issue, page 65), I glanced up at my own picture mounted on the wall and suddenly noticed a "star" in Johnny's image that does not exist in this part of the sky. It must be a passing asteroid, but which one was it?
After close examination of my Astrovid Stellacam3 image, Iâ€™m almost certain the mystery object is a hot pixel.
The image header says it was taken on February 18, 2007, at 2:30 Universal Time, and by going to the Minor Planet Center's online proximity calculator (http://scully.cfa.harvard.edu/~cgi/CheckMP) I could quickly check whether it's a known asteroid. After entering the date, time, and suspect's 2000.0 coordinates, estimated from a good star atlas, I found that no known asteroids brighter than magnitude 16.1 were within 60′ of that location.
Geosynchronous satellites can also be a problem for Northern Hemisphere observers imaging the region south of Orion's belt. But such a satellite would have trailed ½° during my 2-minute exposure, ruling out that possibility as well.
— Johnny Horne