Guiding with full frame

Normally, guiding assmes you want to zoom in on the guide star and display its progress with a small window.
However, in some applications it is useful to have the full guide camera frame available (it turns out to be a handy way of guiding for spectroscopy).
However, it seems that in this case, you can’t selec tthe guide star and it defaults to automatically finding one. Is this right? It woud be really useful to be able to override this (and unselect the taregt star on the spectrograph slit)

What about using the advanced functions to force a star to have a fixed location?

So the context here is that I usually do try to use the fixed position method with the target as the setpoint on the spectroscope slit. However the alternative method I am trying to use arises if the target is very faint and is almost, or completley obscured by the slit. Then you need to select another star in the field.

In this case you use fine manual movements of the scope to position the target on the slit and then quickly turn on guiding where you can then select a guide star. You need full frame to be able to select something. This is where my previous post picks up… It seem to not allow manual selection of the guide star.
In many cases the auto-selection is OK - but not always. This can happen if there is no standout bright field star and any candidate for guiding competes with the target, which might ‘peep out’ from behind teh slit occasionally.

Hamza pointed to a tutorial in French on this form on auto guiding. Hamza correct me if I am wrong, but I believe you take an image( I use infinite loop) with the guide camera and you can place the target on the slit and then use a single exposure place the cursor on the star you wish to guide on. Click on the star and then right click on the image and select an item near the bottom of the menu to ( sorry this computer doesn’t have Prism on it) which says something to the effect to place the crosshairs at the cursor. Then start guiding.

Here’s the link. I used closed caption to follow along.

Correct @amstpils , here is the link :
It is around 10:30

Hi there
I have followed the video (there is enough in the video to make it language neutral :).
Yes, I see what they suggest - I’ll give it a try.

Having used it in two sessions, I can now say this method works well!
It relies on being able to modify the set point during guiding; you just adjust carefully until you see the target over the middle of the slit.

Use of the target as the set point star itself (as I was doing up to now, with a small-window rather than full frame) may still come in handy if the guide image has no suitable candidates (all too faint), but this will be the exception rather than the rule I suspect.

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