I came across this topic as I was interested in learning if SGP would communicate with APCC about early meridian flips. I understand that it will not on its own automatically.
I wanted to share a procedure I came up with, however, that would allow me to begin imaging a target once it passed within the east slew limit of my Mach1GTO. In APCC I set the Meridian Tracking Limits for both east and west. I checked the box for allowing the mount to slew to the east with counterweights up. For my target’s declination, meridian flip could occur 1.48 hours early.
In SGP I split my target into two targets. For the first one in the sequence, I set the stop time for 10 minutes after the start of the East slew “safe zone” time. My subs were 10 minutes, and this meant that the first step of the sequence would end just after the early meridian time of APCC with a buffer of one frame should I need it. The second step in the sequence was for the same target.
When the first one ended and the second one started, the mount slewed to put the scope on the east side with counterweights up. SGP did a plate solve and correctly determined that the camera was now flipped. PHD was started, and the imaging continued. This allowed me to slew 1.5 hours early and continue tracking.
The west tracking limit is also set just in case something happens and SGP doesn’t tell the mount to part or move on to another target. The APCC safety is in place.
Could this be achieved without setting up two targets by setting the Minutes past meridian to flip in Meridian Flip Options to a negative number?
For example if your mount can accept doing a flip 1 hour before the meridian set Minutes past Meridian to -60.
Then when the hour angle of the mount is greater than -1.0 hours SGP attempts a flip, either by doing a slew or by using set SideOfPier if that is available (CansetPierSide returns true).
I tried to do that on my last night of imaging this weekend, however SGP reported immediately that my mount did not support negative values here. You are right that this would have worked if I could have made this setting equal to that of APCC, or better yet make it a few minutes later to allow for a small buffer of time. SGP would command a flip, APCC would allow it early, and all would be well.
However, because of the error message, I could not manipulate the flip value in SGP, so I left it at zero and used my solution of splitting the target into two. Note that this did work for me. The first target, with the telescope west of the pier, finished off at a time just past the early meridian setting in APCC. For the second target, the slew command caused the scope to be flipped to the east side with counterweights up, and imaging resumed for the rest of the night.
It would be nice in the future for SGP to communicate more fully with APCC and honor the latter’s meridian settings, however I understand the conversation from earlier in this thread that there would not be plans for this at this time. I found this workaround that does the job for me.
My guess is that SGP has decided that if a mount does not implement set SideOfPier it can only do a pier flip slew after the mount has crossed the meridian.
However APCC can be set so that a normal slew will do a pier flip early. This is what is happening when you switch to a new target.
If SGP were to remove the restriction on attempting to do a pier flip slew before the meridian then it would work.
Or if APCC were to implement set SideOfPier then SGP would do the pier flip early using set SideOfPier.
I’m speculating here but Jared, Ken or Ray should be able to correct any misunderstandings of mine.
I need a little help here understanding. I run APCC and AP mount. In SGP, I just set a delay on the meridian flip so that it does not flip until it is way past the meridian. I set this limit to taste and go way beyond the meridian depending on my declination. This works on a good part of the sky. The rest of the time, when I can’t image way way past the meridian as indicated on my meridian limits, usually on a northern target, I just adjust it so it does not hit the limit and images as far past it as it can before doing a flip.
Is this the correct way of working with the functionality of both software packages and getting the most flip free imaging time?
I am not sure I see the problem. Either SGP or APCC needs to control the mount – not both. Since only SGP knows what the camera is doing, let SGP control the slewing and meridian flip. Use SGP do the initial slew to target and use the auto meridian flip option. I use an AP1100GTO mount and use the auto meridian flip in SGP on a regular basis. I do not use the “wait for meridian” option, however. When SGP finishes a sub and realizes the mount has crossed the meridian during the sub, it then initiates the meridian flip. If you can image well past the meridian, you can tell SGP when you want the meridian flip to occur. If APCC is polling the mount, it will know a flip has occurred but don’t tell APCC to do any kind of an automatic flip.
A useful feature in the AP ASCOM driver is “meridian delay.” This tells the AP mount how to position itself (how to slew) when the target is near the meridian. Often I use a meridian delay of one hour east. When SGP slews to a target that is east of the meridian by less than an hour, the AP mount slews to the target with the OTA on the east side of the mount and the counterweights high. The scope will then track to the western horizon without needing a meridian flip. In this mode, I disable auto meridian flip in SGP.
What I think you are missing is that the OP wants to do the flip before the meridian, not after. After is fine, you can persuade SGP to delay the flip. It’s doing the flip early that’s the challenge.
Well, that I did not know. I have never actually tried it but thought the -30 would work. Need to bring Ray Gralak in on this. I’ll make a post to the AP group.
Thank you all for your inputs. Sounds like Charlie got to the crux of the matter here at the last post and was able to address your points. I’ll add my own clarifications.
I have a situation where I wish to image most of the night on the same target, and I have a desire to do my meridian flip early, not late.
Starting out the scope needs to begin west of the pier with counterweights down. However, at about 1.5 hours before the target crosses the meridian, the scope could be slewed east of the meridian with counterweights up since it would be in a “safe zone”. This is a desired location for several reasons, not the least of which is that I can monitor the flip earlier during the night in case of error and then go to bed earlier than if I waited until the actual meridian crossing, and certainly if I had delayed the flip even longer.
Another reason is that my scope is slightly heavier than all of my presently available counterweights, and so I can make the configuration east heavy a little bit earlier in the night. This latter reason is not too critical because it guides and images well enough with the scope a little heavy when on the west side, but the improvement can be detected.
APCC allows for slews east to have limits in which the slew can place the scope low and counterweights high. I’ve set these limits (which are set as function of DEC). From APCC I can see how early from meridian the scope will enter this zone. I attempted to have SGP order a flip at this time, and here is where I was stopped. I needed to enter -1.5 hours for the meridian delay, and the response was that the mount did not allow this.
By splitting the target into two and timing it just right, I was at least able to order a slew just after the scope came within this 1.5 hours of meridian, and the east slew with counterweights up option caused APCC to put the scope low and able to now image east heavy the rest of the night. And then I got another 1.5 hours of beauty sleep that night.
I appreciate you bringing this up with Ray Gralak to see if this configuration can be done in such a way that I do not have to split the target into two. In APCC the graphics show that the meridian flip is effectively shifted east (early), and that value is displayed. It would be nice if that could be communicated to SGP.
The AP V2 ASCOM driver does not currently implement pier flips. I asked A-P if I could implement this a while back and they said other things had higher priority so it was pushed back. I will bring it up with them again when they are back from NEAF. It should be doable but there are a lot of features on the “to do” list and I only have so much free time (i.e. I have to multiplex my free time between my day job, family, APCC, the AP driver, and finishing PEMPro V3 and a couple other small projects). If you feel the pier flip (or any other feature) is really important you should post your feelings on the ap-gto list for A-P to see (address to A-P, not me personally) because A-P decides the features that they will have me implement in APCC and the AP driver.
Thanks, Ray. I just posted on the AP forum to follow up with your comments there. I’d appreciate your feedback there that I am properly interpreting the use of both the meridian tracking limits and the east/west with CW’s up limits. Thank you.
AIUI APCC is set up so that the line where a pier flip is done using a normal slew is set to be before the meridian and this is what Ben is doing so that his second target does a flip before it starts. This is done using a normal slew.
What this means is that if SGP were to allow meridian flips using a normal slew before the meridian the pier flip would be done.
Ray: I fully understand being busy and having to multitask! If I had my vote on what I’d have you finish first, I’d vote for PEMPro v3! I can wait longer on any APCC-SGP meridian flipping update. I appreciate your fine work.
I see my original request/wish got some more airtime since I last visited Have there been any more updates to the ASCOM driver/SGP meridian control issue since?
Chris Rowland stated exactly what my request was about. Although Ben Kolt seems to be in a similar position to mine and has found a solution, I don’t want to limit the number of targets and cannot possibly be so organised
Have there been any more updates to the ASCOM driver/SGP meridian control issue since?