PHD momentarily loses guide stars

[tomato]

Last night the atmosphere settled down a bit and my rig was guiding consistently at 0.4-0.5 arcsecs total RMS.

However just before and after a meridian flip, PHD reported “No guide stars detected” for a couple of exposure cycles and then carried on as if nothing had happened. There was no cloud about and no drop in the star SNR value. Note there was also no star lost or star mass changed message and the camera status stayed connected.

Anybody else seen this?

[AKB]

This seems to happen to me fairly regularly, but as it really doesn’t affect anything I’ve not dug into it.   I think we’re using the same mount, Mesu?  Regularly guides at 0.3” – 0.4”. 

I’m using a really basic ASI120 as the guide camera, and I’ve noticed, outside of the guiding context, that sometimes an image is shifted wholesale across the frame, reverting to normal on the next.  Not sure if this is a camera or USB thing, but it would certainly cause the guide stars to be missed…

Tony

[gorann]

I remeber often seeing "star lost" or "star mass changed" (whatever that means), but I cannot remember “No guide stars detected”. In any case I find that the Mesu will do its job until PhD finds it again.

[tooth_dr]

13 hours ago, AKB said:

I’m using a really basic ASI120 as the guide camera, and I’ve noticed, outside of the guiding context, that sometimes an image is shifted wholesale across the frame, reverting to normal on the next.

This happened with my old 120MM as well.  It eventually became too unreliable so I swapped it out for a 290MM.  I'm using SGPro and it seems to have an issue if there is no guidestars detected - it stops the sequence and goes into recovery mode.

[tomato]

Thanks for the replies, I use an ASI 120 mini which is a few years old now, and a wholesale shift in the image would certainly result in the effect I’m seeing. It didn’t happen for the first 3 hrs of the session so maybe it is temperature related. Anyway, I have another 120 of more recent vintage, so I’ll swap them out and see what happens.

[ONIKKINEN]

Similar thing happened with my 120MM as well, although in the guide log i also saw that SNR and star mass dropped to 0 with no cloud or other obscuring going on.

Not seen that with the 220MM i upgraded to.