I have been having an on-going problem with SGP control of Shelyak Ascom Dome control – but only after Plate Solve. The dome is slaved to the scope in SGP (using the Shelyak Ascom driver for the dome). In general use, the dome will follow the scope – and I don’t have any problems. Lately though, rather than working on one target, I have tried two or three in the night. Then the plate solve routine to place the scope on the new target causes me problems. I tried once or twice to view the dome tracker log – but it is huge. There was no point in trying to send something in from a nights observing.
Tonight I did a small test. I initially synced the scope by aligning on a star (Sirius) and then syncing via The Sky X (SAE). With the scope synced, I slaved the dome – it adjusted correctly – so all well.
I then did a plate solve (PS2) and I guess the scope and dome were exactly on position – I heard no movement from the dome. On the downloaded plate solve frame, I picked a random spot and called for ‘Center Here’. SGP went through the motions and had adjusted the mount at least twice to get to the center here position. During this process the dome moved off a couple of degrees and back again – at least twice. The mount movement would have been negligible and this time the dome movement was small and did not interfere with the SGP getting other frames for plate solving. (In truth the dome should not have moved at all - the shutter is wide enough). I have seen the dome take off more than those couple of degrees at the juncture – and getting a frame for plate solving was then impossible. That did not happen during the test tonight – BUT at the final plate solve and scope sync – the dome did take off (about 70° or 80°)…and then came back to the correct position.
At this stage, I have no idea if the problem arises with SGP or the Shelyak Ascom driver. One thing that comes to mind (since the dome follows the mount without problem – when no sync is involved) is that SGP initially puts out the scope sync position in J2000 before sending JNOW positioning to the mount (Takahashi EM400). Does SGP actually SEND that sync info and then send updated (J2000) info? Is there two syncs coming in, one after the other to the mount? I know that we are not talking about 70 or 80 degrees difference between the sync positions – but is there any possibility that the problem lies here somewhere? As it is, I cannot leave the scope unattended for change of target or indeed a meridian flip for fear of a big excursion by the dome, the camera not having a clear shot at second or third frame for solving and then SGP going into recovery mode……and then another possible similar cycle at the next try.
Two logs on DropBox from tonight’s test – your thoughts would be appreciated when you get a chance.
Times – roughly:
212133 First solve & sync with PS2 (Mount already synced manually)
212822 Center here initiated
212946 Final solve & sync after which the dome went ‘walkabout’
213150 Dome back to correct position – stop the test.