Exactly Chris.
The way you have set things up is consistent with not creating a conflict. Since you set the flip to occur 22 mins after the meridian and tell SGPro to wait for the meridian, it will always have gone past the meridian when it starts its last exposure before the flip. When the Mount flips, SGPro is expecting the OTA to move from the east to the west side of the pier. Since, when The SkyX is asked to point to the object you are imaging, it is in the red zone already, it will move the OTA to the west side of the pier. No conflict.
The other alternative to the way you’ve set it up and a simpler method I believe, is to set the “Minutes past the Meridian to Flip” to 0 and only tick “Auto Centre after Meridian Flip”. i.e. you do not really need to tick “Wait for Meridian” and then set a flip time to be just longer than your longest exposure. For my proposed “simpler” set up, SGPro will start an image if it is before the meridian and it will finish it, even if it goes past the meridian. Once that image is finished, the object will be past the meridian and SGPro will initiate a flip. Since the Flip Hour Angle on The SkyX is 0 degrees, as you specified in your tutorial video, this is in the red zone and when asked to point to the object, The SkyX will move the Mount such that the OTA moves to the west side of the pier, as SGPro expects…no conflict.
The only thing one has to ensure is that the slew limit is set such that the OTA can go past the meridian by more than the longest exposure!
Incidentally, it may be worth considering just that scenario i.e that someone may have an exposure time which is greater than the slew limit past the meridian. Imagine a 60 min exposure and 30 minute slew limit for example.
Your set up would not be possible, because you couldn’t set SGPro to flip after the slew limit for obvious reasons. For the set up I’ve suggested, there are circumstances where the Mount will reach the slew limit before an exposure, which was started before the meridian, is complete.
In this case, there are three alternative configurations to avoid an infeasible outcome as discussed above.
Firstly the astro-imager could tick “Wait for Meridian”, where the “Minutes Past Meridian to Flip” is set to 0. In this case, supposing the Mount is 59 min before the meridian, since the exposure will take 60mins and go 1 min past the meridian, SGPro will wait until the meridian and then flip. This means a 59 minute loss of imaging time in the worst case. In the best case an image started 61 mins before the meridian will finish 1 minute before the meridian and just before the flip, with minimal lost time…just the safety factor. The average lost imaging time will be ~30 mins.
The second alternative is to set the “Minutes Past Meridian to Flip” on SGPro, as well as the Flip Hour Angle on the SkyX, to just before the slew limit, say 29 minutes and tick “Wait For Meridian”. In this case if SGPro goes to start an image say 30 mins before the meridian, the 60 minute exposure will take it past the meridian flip time and it will wait. Again a loss of 59 mins. If it starts an image 32 mins before the meridian, which will finish 28 mins past the meridian, there is a loss of 1 minute. In fact alternative two is no better or worse than scenario 1. Both avoid a failure, but result in an average loss of imaging time equal to half the exposure duration.
The third alternative and the best solution is to set the flip to occur before the meridian. In your video you suggest that this is not a desirable situation, but in fact there is no problem with it. In this case you would calculate how many minutes before the meridian the flip needs to occur to avoid a conflict or a significant loss of imaging time. This = Texposure - Tslew limit = 60 - 30 = 30 mins. So the flip needs to occur 30 mins before the meridian. In this case I would set the Flip Hour Angle on The SkyX to -32 mins and the same for the “Minutes Past Meridian to Flip” on SGPro. “Wait for Meridian” should be unticked. (By the way the word “Meridian” in this dialogue box in SGPro is a misnomer . They should say “Meridian Flip Time” as it may not correspond to the meridian at all)
If SGPro arrives at a situation where it is say 33 mins before the meridian, it will start the exposure, which will finish at 27 mins past the meridian. 2 minutes later a flip will be initiated and that constitutes the lost imaging time i.e. again the safety factor. If however, SGPro finishes the last exposure such that it is 31 minutes before the Meridian, it will initiate a Meridian Flip with no loss of imaging time, save that for the flip itself which is inevitable in every scenario.
Chris, do you agree with all this? If you do, it may be worth considering a reworking of your tutorial video. You have a very nice presentation style and I think there would be benefit to firstly simplifying the basic scenario as I suggested and how to manage scenarios where a Meridian Flip at the meridian is not always desirable. If you don’t want to go into such detail, perhaps you can just mention that there are scenarios where the imager may want to flip before or after the meridian and that in such cases they need to ensure that the Flip Hour Angle on The SkyX and the “Minutes Past Meridian to Flip” are the same.
