I’ve updated the ASCOM driver for the Celestron telescopes to avoid the error in slews that has been a source of considerable trouble for pointing accuracy for years. This driver measures the difference between the slew target and the position the mount reaches and applies that difference to subsequent slews. The result is that the position reached should be closer to what is required.
It’s on its way to the ASCOM site but if anyone wants a preview the installer is on Dropbox here:
As a user you need to do nothing. The driver handles it transparently.
The reason for the error is that Celestron were not allowing for the time that their slow final approach slew was taking so the mount always ended up as a reported position that was a few seconds behind the sky. The final slew is always about the same distance and time so the error is consistent. I’ve been hoping I could persuade Celestron to fix this.
As always, if you think this is causing problems let me know and include driver logs showing the problem.