What model mono cameras would you suggest, and what are their advantages and limitations?
Can you say more about moving stacks / synthetic tracking?
The most common software package for producing research-grade astrometry for asteroids is called Astrometrica. It has a feature called "track and stack" where you load a whole series of images (your stack) and if you know the position angle (PA) and speed of the asteroid (from earlier observations), then when Astrometrica stacks the images, it offsets each one based on the image time stamp and the PA and speed you entered into the program.
The other popular program is called Tycho tracker. It is a synthetic tracking program, meaning it can do a blind search for moving objects by generating a large number of postulated PA and speeds, performing the stack, and then looking for objects which are stationary in the stack. This is a common method used by professional observatories also. Tycho can also stack based on a manually entered PA and speed as I understand it. It was written by a fellow here who's handle is asmcoder8088.
I don't have a specific camera recommendation other than it needs these criteria (IMHO)
- mono only (because it produces a more accurate centroid than a OSC camera)
- CMOS (because they are fast)
- Needs precise timestamp (which is usually a SW issue).
The reason I would avoid OSC is that you are trying to get a measurement accurate to a small fraction of an arc second. If you are imaging "normal" and reasonably bright asteroids, the residual fit to your positions should be around 0.3 arc seconds, which is much less than the size of your pixels typically. A good plate solve with a polynomial fit can have a RMS error as low as 0.07 arc seconds, with a mono camera. If you are producing images with residuals as large as an arc second, they are pretty much useless. You can check your obit fit residuals by taking a set of same-night measurements of a known asteroid and pasting them into an orbit calculating program e.g. find_orb, which will calculate a set of possible orbits, pick the best one, and then tell you what is the error of your observation set to that orbit.
I have some ASI ZWO cameras which are very nice but when you use the ASIimg program, at least the version I have, the image time stamp can be off by six or seven seconds which is terrible. The way I found this out was by creating a high speed clock image on my display, and then attaching a video camera lens to the astro camera and taking fast images of the computer screen. Other image capture code that uses the ZWO camera driver doesn't have this problem, apparently. But in any case you have to verify that the capture time is accurate, and also in your computer you need to absolutely be sure you have precise timekeeping, which is easy with a GPS synchronizer or at minimum a time sync service, and you probably want to double check using shortwave radio.
An example of what can be done from light polluted skies, check out the Northolt branch observatories team
I also recommend the Roger Dymock book "asteroids and how to observe them" ISBN-13 9781441964380
You can also do asteroid light curves using MPO Canopus or AstroimageJ but that is a different discipline.
Edited by 555aaa, 09 December 2021 - 11:56 AM.