Hi, I need some advice. I have a Pulsar dome, which is calibrated to Az 0.00 degree (North Star). When I calibrated the Dome rotation correctly to park /home position.But when I unpark the mount it move 20 degree east, therefore the dome shutter is off center to the telescope position.
The park position of the mount is AZ 000.02min.38seconds, when it should be a zero, this is too small a difference to the 20degrees movement to the east before even starting. Taking into account that the Dome calibration is fine, as it pointing correctly both mathically and phyically (compass), what is the solution so that the mount accept the true position of the dome.
I am using SGP, a 10micron 2000 mount and Pulsar Dome.
The telescope/mount is polar aligned, and RA/DEC are both in SGP & Mount shows similar figures.
Any suggestion will be appriciated.
Thanks
Charles
Futher testing to the above, I have done a recalculation of the slaving data in SGP, and slew the mount around the 360degrees and each time the shutter was well within the telescope point of view. I also did a recalibration of the dome and its correctly stop at the 0.00 point angle. However if I ‘UNPARK’ the mount it move the dome shutter to 20 degrees east!!.
If I park the telescope *to 0.00’ home position using the hand control, the dome will only move back to 0.00 by forcing it via SGP or the dome control panel. if I switch to ‘UNPARK’ using the handcontrol, it will move back to the 20degress east.
What I havent tested is if I slew to a target, will the dome starting from this 20 degree will correct itself and slave to the correct AZ position.
I have look at the Log and found that there has been an adjustment is below>[07/03/21 19:40:11.346][DEBUG][Main Thread][NONE] Dome: Finding Home
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Observatory: Calculating new position using:
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Azimuth: 0.03251
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Altitude: 36.5046
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Hour Angle: -170.0790354023
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Pier Side: West
[07/03/21 19:40:27.092][DEBUG][Dome Thread][NONE] Observatory: Adjustment needed, slewing to Azimuth: 27.2208640072396
[07/03/21 19:40:27.113][DEBUG][Dome Thread][NONE] Dome thread is IDLE…
[07/03/21 19:40:36.410][DEBUG][Main Thread][NONE] PopulateDataModel: Transferring view to the data model…
[07/03/21 19:40:36.425][DEBUG][MF Update Thread][NONE] Performing serialize…
[07/03/21 19:40:37.262][DEBUG][Dome Thread][NONE] Dome thread is IDLE…
[07/03/21 19:40:47.572][DEBUG][Dome Thread][NONE] Observatory: Calculating new position using:
Can someone explain if the adjustment is done by SGP or the Mount?
thanks
Charles
Charles,
I’m afraid I can’t answer your question, but I have the same issue. My Pulsar dome does exactly the same as yours when I unpark the mount - though I’ve never actually checked exactly what the angle of the dome is. Like you though, when I slew to a target, the dome is positioned correctly, so I just shrugged my shoulders and decided it was one of those mysteries that I would never get to the bottom of. Well, that is not entirely true - I did wonder whether the issue was more to do with the sensitivity of the dome azimuth calculations to things like mount E/W offset and the pointing angle offset of the mount when you sync it. The higher up the dome opening that the scope is pointing, the bigger the change is required in its azimuth to allow for a given azimuthal change in the scope position. I don’t know if you’ve ever imaged anything that goes close to the zenith, but the dome has to move quite quickly to keep up with the movement of the scope at the point, which is when it is looking through the slit close to the top of the dome. So I did wonder if the calculations were moving the dome to this location because that would place the centre of the slit smack bang in line with where it thinks the scope is pointing.
To illustrate this, I just did a calculation for my location and from the home position pointing North, 1 degree movement of the scope in declination would require 2.5 degrees movement of the dome in azimuth. And an offset of the pier of 100 mm east or west would be enough to move the dome to an azimuth of 20 degrees even when it is pointing due North, but that would be something that you set in the Slave Settings, so you’d know about that. So maybe it is just a quirk of the geometry of the system?
You’ve piqued my curiosity now, though, so maybe I shouldn’t have been so accepting of this odd behaviour!
Terry
Thanks Terry for your thoughts, though I target last night IC5070 started from the park/home postion (did not unpark) and the dome hit the target spot on thr middle of the shutter, mind you it was AZ 90 and a low ALT, I will do further test near the zenith, I also thought about the offset, and I did look at the mount manual for the 2000 for exact measurement just in case my E/W offset were off. Hosestly, I have been spending too much time to this, if the dome slew to the same as the telescope, I am good with this, this issue might be classified an ‘x-file’ 
Best
Charles
Charles,
Having nothing better to do on a wet Sunday afternoon, I was having a bit of a play in the observatory. When I unpark, my Pulsar dome goes to about 340 degrees azimuth (i.e., west). I went into the Slave Setting in SGPro and my settings are that the pier is, as near as I can tell, centred in the dome, so there is no E/W offset, and the only N/S offset is due to the backward tilt of the EQ6R mount. So as an experiment, I put in an East offset of 100 mm, which to my thinking would mean that the dome would not go as far as 340 degrees as I am telling the software that the mount is further to the right as I look North. What happened was just the reverse, the dome went to 330 degrees, i.e., further left! So I tried an offset of 100 mm West, and that resulted in the dome moving to only 350 degrees, again, exactly the opposite of what I’d been expecting. It is possible that I am getting my pluses and minuses mixed up (or even that SGPro is I guess), but since I have no offset in my configuration, that should be irrelevant. My next experiment will be to use the ASCOM device hub and see if it does the same thing. This is now just because it is bugging me - like you when SGPro slews to any object, the dome positions itself perfectly as far as I can tell, so there is not an issue there, it’s just that it shouldn’t do what it’s doing, so I’m not giving up on it just yet!
Terry
Oh no, I wish I hadn’t set off down this rabbit hole 
I’ve just tried using the ASCOM Device Hub with the same setting for the dome offsets, etc., and it is even worse than SGPro - even without unparking, the dome wanders off to 323 degrees. After a bit of slewing manually backwards and forwards, the problem seems to be only when the telescope DEC setting is at or close to 90 degrees. Move off to 92 degrees for example and the dome moves back to where you would think it largely should be. I cannot see any reason why the calculations should fall over so badly in this region, but since Polaris is not a usual target for astrophotography, I guess I can live with it. It still bothers me though since my own hand-coded calculations (I once had ambitions of building my own dome rotation system before copping out and getting the Pulsar one) do not have an issue at that position - sine and cosine values are, after all, pretty well defined at 90 degrees. Anyway, enough time has been spent on this now and this anomalous behaviour can be left as one of life’s unsolved mysteries.
Terry
Hi Terry, my observatory is in south of Spain, in a mountain town called Istan, so i am a bit luckier with the weather, my offset setting are very similar to yours, the E/W offset is as well zero, though my unpark position does not goes as far as 300+, its around the 20s, now listen to this, last night I left it to run overnight and had it to stop around 5.30, by mistake I did not tick the option in the Observatory Setting ‘Park Observatory with Mount’, so the telescope/mount was pointing North, but the shutter was pointing at 45 degrees east, when I unparked the dome when to around 72degree, and I thought , could SGP did not recongised the mount current park position (0.00) and just added to the last mount position (45 degree) the original position. (45 + 27 =72 degree).
So, basically SGP should regonised the mount park position even if the mount is park, and when unpark it should keep this position.
Charles
Hi, as I was writting this , you last comment came in, true , I will do the same as you said, forget about this and just start from a park position.
best, and thanks for trying.
Charles
I was already jealous when you mentioned your mount, but an observatory in the mountains in Southern Spain! We’re moving house in a few months to a location with darker skies, which is great, but I’ll still have to contend with the weather in the north of England 
It just makes me appreciate the clear nights all the more 
Terry