On May 7, 2021, at 10:44 PM, Dale Ghent <daleg@...> wrote:


Hey Luca,

Ah yes I see. This particular mechanism is out-of-band from ASCOM. From what I gather, SGPro's own network API implements an endpoint that allows an external app (such as APCC) to inform it with the hour angle meridian limit (I think) of the mount's current declination. APCC hits this endpoint with that info and I guess SGPro takes it under consideration as a form of temporary meridian limit (or delay, if the limit is "beyond the pole.") I'm not an SGPro user or familiar with its internals so I can only guess at how it uses this information.

NINA does have an implementation of the SGPro API that is just a subset of SGPro's full API. It's there to service things like 10micron's pointing modeler and (hopefully soon, I need to catch up with Ray on this) APPM. But we NINA devs aren't interested in adopting SGPro's API as our own, and would rather keep it to the subset of functionality that is currently is. Eventually, we will invent our own design that is better suited to NINA's functions and capabilities. But that time isn't right now.

So where does this leave making NINA aware of meridian limits? In NINA 1.11, which is the current development branch and contains the new Advanced Sequencer, there's a new plugin system. A lot of internal app interfaces are available through this plugin system. One of the NINA contributors has made a plugin that uses a user-supplied file of meridian limits to dynamically adjust the flip time based on the scope's declination. Its data format is a mapping of declination to east+west hour limits in 1 degree increments. APCC's MLM file maps those limits using the Meridian Angle in 1 degree increments. I'm going to look at extending this plugin so that it can read APCC's MLM file and just derive the limits at the current declination from that. The developer of this plugin has been using it for some time to solve the same problem that APCC's meridian limits (and delay) feature solves, so extending it to grok the MLM file format is no big deal.

This will give us a solution that avoids having to further extend an API implementation in the app that we'd rather not pay anymore time to, and doesn't make us have to rush to implement our own API to service just for this one feature (and then get Ray to implement it on his end in APCC.) Instead, we'll just read the MLM file directly and include a user-adjustable setting to flip the scope at some defined number of seconds or minutes before the limit is reached to avoid APCC reacting and potentially parking the scope or stopping tracking.

We'll hack on this and I'll let the group know when there's something usable that's available.

/dale

On May 7, 2021, at 06:38, Luca Marinelli <photo@...> wrote:

Hi Dale,

A few days ago I posted an example of meridian flips and CW up imaging with APCC and SGP:

https://ap-gto.groups.io/g/main/message/78270

The key setting that allows dynamic (declination-dependent) meridian flip setpoint and CW up or down imaging when allowed by the APCC meridian limits is the checkbox "Send Limit with offset to SGPro" in the Meridian Limit tab in APCC. Does this checkbox only work with SGPro or does it also work with NINA? Maybe Ray can comment why SGPro is special (if it is) and how it is able to take advantage of the full, dynamic meridian limit setting, instead of being limited to a static "flip 15 minutes after the meridian" kind of scenario. It would be great if all imaging applications (not just SGP) could take advantage of this powerful feature.

Cheers,

Luca