maudette I use an ONAG for tracking and need 3 seconds exposure to get decent stars. Is this refresh rat high enough to allow the AM5 to be stable?
In a different thread on this forum, the slope of the periodic error of ZWO's mount that are in users' hands appear to fall somewhere between 0.15 arcsec/second to 0.3 arcsec/second.
If your mount happens to be have a slope of 0.3 arc-second/second, and you are taking a 3 second guide exposure, the guide star would have moved 0.9 arcsecs while taking the guide exposure. So, it is unlikely that you would be able get the RA axis to guide to better than that (probably worse). Add in the declination axis, and you are probably talking about a total RMS guide error of no better than 1 arcsec.
Is that good enough guiding accuracy for the plate scales which you are using?
If you are willing to write your own autoguiding software, 3 second exposure is not a problem even with these mounts that have large periodic error slopes; but you will need to change to a different guide paradigm than what we have today. See post #99 in this thread:
https://bbs.astronomy-imaging-camera.com/d/15989-getting-the-best-performance-from-my-am5/99
Chen
