Had a very interesting session doing some photometry on asteroids last night.
You can usually observe their rotation by a dip in the magnitude over a period of time. The more irregular ones show the greatest fluctuation. I noticed that asteroid 1727 Mette is well-placed in Serpens and has a fast rotation of about 3 hours, and I managed to capture 5 hours-worth of images. It's just a small object about 5-8 km in diameter and is a Mars-crosser asteroid, orbiting every 2.52 years.
Here is a light curve I prepared using data from the photometry program Muniwin. It's derived from 100 x 3 minute exposures, binned 2x captured with an Atik383L+, Omegon RC cam.
Once Muniwin had processed the data it came up with this strikingly obvious rotation curve, with its magnitude ranging by about 0.35 magnitudes over a period of 3 hours, matching the official rotational data with a peak at around 23:37 and another at 2:32. As usual with asteroid magnitude curves, there are two peaks and troughs per rotation. There are a few binary asteroids, like Antiope, which behave like eclipsing binaries when lined up correctly, so I hope to capture that some time. Times are British Summer Time (1 hour ahead of UT)
Here's a capture of the whole field, with the position of Mette at 22:24 and 2:57 highlighted. Based on two 5 x 3 minute exposures. The brightest star here is magnitude 7.8 and the field of view is 38.5 x 29 arc minutes.
And here's an animation of 9 cropped frames over the session, 15 minutes apart
Edited by Lukey, 18 April 2021 - 06:40 AM.