Photographing an Asteroid (by accident)
Time-lapse of the movement of asteroid 10724 Carolraymond. Images were taken on December 14, 2022, from around 18:00h. Total timespan is approximately 5h.
Serendipity is a crucial aspect of scientific exploration. And also in amateur astrophotography, one should always remain open for unexpected observations. Even if not exciting by any objective measure, they can give just that little extra joy around photographing a certain target. Recently such an unexpected event happend when I was processing the images of M74, a galaxy in the constellation Pisces. The processing was a bit of a struggle in the first place, as the flats had not very well corrected some serious dust bunnies, probably due to some inaccuracies in rotation of the filterwheel. And just when I thought that the RGB stack was in pretty good shape, my eye fell on what first looked like a colour artefact of some sort. A short red/green/blue line at one of the edges of the frame. The first thought was that this was some sort of unexplained aberration. But the image was a stack of multiple subs, and only in this one specific location there was this line. Also it followed a very distinct pattern of clear red, clear green and clear blue. Soon it occurred to me that this should be some kind of moving object that had travelled through the field of view as I was rotating through my set of RGB filters. And the total cycle of that rotation was three hours, so whatever it was, it was not moving very fast. It dawned on me that it should then also be visible in the luminance subs that were taken just before the RGB subs. And indeed, when closely examining that stack, it also showed a short stripe at the same location. When blended in with the RGB stack, both stripes were completely in line with each other.
In subsequent stacks from individual filters, the asteroid’s path becomes visible.
So what was it? The slow speed excluded any man-made object such as satellite, plane, etc. The speed of travel was more like what I had seen from comets. So the planetarium program SkySafari was checked for any comets that were currently visible. But there were none in the constellation of Pisces at the time of the observation. I posted the question on my local astronomy society and quickly, one of the members had found out that it was an Asteroid. More in particular asteroid 10724 Carolraymond. Matching the exact time of observation with the location of the asteroid confirmed that this little Magnitude 17.6 asteroid was wandering through my frames.
Asteroid 10724 Carolraymond
The asteroid is part of the main belt of asteroids that orbits between Mars and Jupiter. At a distance of 2.4 Astronomical Units (AU’s), this small, 4.14 km wide rock, orbits the sun every 3.6 year. It was discovered at the Anderson Mesa Observatory in Arizona, US on November 5, 1986 by the astronomer Carol Raymond. As can be seen from the number, it is one of many asteroids, also referred to as small planets, known to date. A full list can be found on Wikipedia. When turning on the option ‘show asteroids’ in SkySafari, a high concentration of asteroids can be seen around the orbits of the other planets.
The astroid belt as seen in the planetarium software SkySafari. Each yellow dot represents a known asteroid. The band aligns very well with the orbits of the planets, here seen using lines of different colours.
Asteroids are a common object in our solar system. And surely many astrophotographers have much better images of them. But the serendipitous nature of this image made it worthwhile sharing it here. Perhaps it can inspire others to search their images for tiny mobile objects as well. And before they grab their clone-stamp tool it might be worth checking out what these strange ‘artefacts’ may actually resemble.