Help with PHD Star Lost recovery

[Pawan Singh]

Hi 

I use NINA/PHD2 with ASI120, 50mm guide scope for guiding. My mount is NYX101.

For some reason, at around 1:45am for last two nights, PHD2 loses star for guiding and then never recovers.

I have added a link to the debug log, guide log and "star lost" photos. I have also added two subs from the main camera where this starts to happen.

I was going to use NINA's recover from drift feature, but that will not work because it seems that after PHD2 stops guiding, the mount is not tracking at all and may be that causes PHD2 to completely lose it.

I tried to look at the debug logs and some of the star lost pictures and can see that there are better options in the frame - but PHD2 must have some logic to keep trying the "star lost" coordinates for X number of attempts. But it seems that when it tries to change the star, it no longer is able to pick one.

Here is the link to view the debug/guide logs and star lost frames.

https://www.dropbox.com/scl/fo/iw4nct7hsnryfmcx60pmj/AAEb2kgbyrcOunmUbfQ_3gY?rlkey=aohr3nib1zv7oxrgv9u85mc49&st=qc4emby2&dl=0

Thanks

Pawan

[Bruce Waddington]

Did you happen to notice the alert message at the top of the PHD2 main window:

Alert: After 16.0 sec the camera has not completed a 1.0 sec exposure, so it has been disconnected to prevent other problems. Refer to Trouble-shooting section of Help.
PHD will make several attempts to re-connect the camera.

This problem started at 23:20 and pretty much went on continuously from there.  All of your continuous lost-star events started at 01:42 when your scope was pointing only about 3 minutes east of the celestial meridian.  From that point on, it looks like the mount either wasn't tracking at all or wasn't tracking accurately.  Do you have some kind of tracking limits set in the mount?  Obviously, if the mount isn't tracking correctly, PHD2 isn't going to be able to find and track guide stars.  If you don't have tracking limits set, you probably have a cable-routing problem that is interfering with the mount close to the celestial meridian.  That may also be contributing to all the guide camera disconnect problems.

Please read the User Guide to understand how PHD2 deals with lost-star events.  

https://openphdguiding.org/man-dev/Trouble_shooting.htm#Problems-_Lost_stars

Bruce

[Pawan Singh]

Bruce

Thank you very much for the reply! I think I have enough hints from you to be able to figure this out now!

Yes - I do get the error about the camera --- but it recovers. I will be replacing this ASI120mm camera to see if that problem gets better.

I suspected it had to do meridian flip --- but I did not check that. That is a great hint!

[Bruce Waddington]

I don't think I'd start by replacing the camera, the problem is much more likely to be coming from the USB infrastructure, especially the cable.  And if you've got cable-routing problems, that can also affect the camera connection.  This is all stuff you can test during the daytime, there's a fairly length testing procedure described in the User Guide.

Bruce