LX90 and positioning errors with Cartes Du Ciel

[MarshMan]

Hi all. I have not posted in the forums much, this is my first thread, so go easy on me.... I recently purchased a Meade LX90, second hand, got a great bargain on it, second hand for under a grand. Anyway, it all works fine, and using Autostar, stand alone with scope, it will align, position, track, all just fine. After a few hours of being on one object, the object will track slightly out of center, but not an issue really.

My question is, with the 505 cable set, I have been able to easily connect the scope to the laptop, and control the scope from Cartes. The problem I am having is, when I tell the scope to move to a selected object in Cartes, it moves to it, but is consistently about 1.5° degrees out in RA, when it thinks its on the object. It seems to be that it is out to the west in RA.

Now, I thought, while it was repositioning that maybe, it had disabled the tracking function, and it was not able to calculate a correct position, but at a degree every 4 minutes of movement, if not tracking, it couldn't be this. The average reposition time was only about 30 to 45 seconds, equating to only a handful of arc minutes, if that was the problem.

I have tried the "sync" function in Cartes, this did not help. Is there some sort of communication thing going on here, that I am not aware of. I have scoured the internet trying to find a solution, but there is nothing about it anywhere.

If anyone knows or can help, it would be fantastic.

Kind Regards, Adam.

[AndrewJ]

Gday Adam

The gotos in the LX90 ( 497 type Hbx ) are normally quite good and don't "lose position" when doing gotos. Some people report delays when manually slewing, but not when doing gotos.
Based on the error being 1.5deg, it sounds like there "may" be a time error involved.
Are you using the ASCOM driver or CDCs raw connection????
If ASCOM, there is an "on connect" setting in there that can reset the scopes time after aligning, and this can cause all sorts of grief.
Sooo, is ASCOM involved and if so, is it set to synch the time on connect.

Andrew

[MarshMan]

Thanks for the reply Andrew. No, I'm just using the native drivers in CDC. I had another play last night, using a different alignment method with the scope, the manual 2-star method. Obtained a very accurate initial alignment, then linked up the PC and CDC. After a few slews to objects, and syncing CDC each time, I was able to land objects in the field of view at about 100X mag. Objects were typically only about a third of a field of view from the center, even after crossing to the opposite side of the sky.

So, I think maybe on the first try, I stuffed something with the setup, initial alignment, etc. Seems to be ok now.

Thanks for the ASCOM time setting info, something to watch out for.

Cheers, Adam.