Tandem scope setup


Of all the automation software Voyager looks to (probably) suit me best. I do not have a trial installed on my scope PC yet so this question maybe answered by “have a go” but I like to check things first.

Currently I have a Paramount, tandem (side-by-side) scopes and a Pulsar dome. The dome is set up fine via SkyX64 and does align even with the tandem setup.

I have looked at the dome settings in the wiki and can understand the scope east/west - north/south - up-down settings.

However I cannot see where I would input the scope offset from the RA/Dec intersection (both vertical and horizontal, though I appreciate those are slightly incorrect terms for a GEM) as I have with SkyX. I can see there is a GEM offset which simply seems to be the “vertical” distance which assume the scope is directly over the RA/Dec intersect. There is an azimuth offset but it is unclear (to me) what this does.

Essentially I am asking how does Voyager accommodate a tandem set up? I can use, from my understanding, Voyager to connect to TheSkyX dome addon but there seem to be 2 (potential) issues.

  1. There is a thread on SB website discussing this very setup causing problems (that may be resolved though)
  2. There’s a bit of a cryptic warning in the wiki about a warning that pops up.



Hi Paul,

information about Dome setup here:

Terms and settings are the same of POTH and Device HUB system. Azimuth offset +/- is a fixed value added (or subtracted) from the calculated final azimuth for dome, can be useful in array setup.

GEM Axis Offset: The distance from the center of the Right Ascension axis to the center of the telescope. This value can vary depending on how your scopes are setup on your mount. It is best to use some trial and error here. If the top of your scope is being eclipsed by your dome increase this value. If the bottom of your scope is being eclipsed decrease this value. Value is expressed in millimeters

Here is more information that I found useful when I developed RoboSync:

Here info from Device HUB (page 5):

I hope this helps.

Voyager disclaimer about using TheSkyX dome follow their disclaimer about use in Third Parts interface for external application (like Voyager). Here reported our disclaimer:

Voyager can manage TheSkyX Dome Add On but using an internal system of status regarding shutter, homing and park. This because TSX, like the Software Bisque also disclaimer in their documentations, cannot handle in same ways all the various brand of Dome. The status is weak at startup and will be real when operation will be done during the session, moving status is everytime relaible. Please check your dome with Voyager in trial before using under the dark time or contact support mail of Voyager for more info if avalaible.

I suggest to use RoboSync instead.

All the best
Leonardo Orazi

Hi Paul
I’m the chap who had the recent thread on the SB site about TSX, Voyager and a Pulsar dome.
I too, have a tandem setup on my MX+

Perhaps if I explain where I am with this now it would be helpful to you.

I operated for a long while with the original Pulsar 32bit driver driving the dome through TheSkyX32 dome addon with Voyager controlling the dome through TheSkyX32. Everything worked very well.

My problems started when I mover to a new computer and started using TheSkyX64.

Pulsar do not at present have an 64bit ASCOM driver that works with my system. Their software chap has been trying very hard but we do not have it working yet.

The older 32bit ASCOM pulsar driver works well directly from Voyager and as it has no connection with TheSkyX64 dome addon (because it is not in use), it works the dome fine with TheSkyX64 controlling the telescope.

I personally like to see the Dome slit overlay on the TheSkyX64 planetarium as it is a good check that everything is in sync so I would still prefer to use TheSkyX64 dome addon to control the dome. The other way of doing this is with an X2 driver. There is an X2 driver for the Pulsar dome which works fine in controlling the dome directly from TheSkyX64 but not with commands from Voyager.

Matt Bisque has spent several weeks and many iterations of a test X2 driver getting to the bottom of the problem. As it turns out, my problem was that, although my Pulsar control box controls the dome rotation, it does not have shutter control connected. This is because I use a separate IP linked switch and a dead man’s relay from a rain sensor to control the closing of the shutter. Although the Pulsar control box knew, the X2 driver wasn’t picking this up so Voyager seemed to be waiting for shutter responses that weren’t coming and did not do much else.

I now have an interim driver from Matt that works and has allowed Voyager to control the dome without waiting for shutter information.

If your pulsar dome has both rotation and shutter control installed, you may be good to go with an X2 driver.

I also found I could get the older pulsar 32bit driver working with TheSkyX64 by connecting under the dome control first to an ASCOM hub (such as the OPTEC version) and then to 32 bit dome driver but this is all a bit messy.

Good luck with it all



Thanks for taking the trouble to answer.

I have a 2.7m model using the Pulsar rotation and shutter control. The main controller does have a relay that will read from an external trigger such as my cloudwatcher. It isn’t a deadman switch as such but if the cloudwatcher triggers an unsafe event it will close the shutter - I assume you know about this? I could rig up a relay cascade to act as a deadman or even an Arduino that would integrate a deadman and cloud input and trigger the main dome box accordingly. I appreciate still not a direct deadman to the shutter though,

As I’m using the dome in its standard configuration I hope control is more straightforward than yours though so thanks for the reassurance.

As to the driver it’s no surprise to hear it’s taking a while. I’ve had a fair few hardware issues I’ve had to sort and reported bugs (with no solution) in the native Pulsar software controller. The X2 driver from Rudolph (I think) at RTI-zone has been fantastic so as you say hopefully should be fine.

Reqarding the slit then I’d love it to overlay but with my tandem setup the dome effectively has to be offset from the azimuth for the scope to align (I have a wide tandem with a 16" on one side and 8" on the other).