Autoguiding to exact Camera.StartAutoguide(r,x,y) position

[Forum_2016]

Hello

For high-resolution spectroscopy I am autocalibrating every 10 minutes with an
(astroart script controlled) Thorium-Argon lamp and a flip mirror. This flip mirror
- which has to be activated during calibration - blocks the complete field of
view including the guiding image.

Therefore I stop autoguiding with Camera.StopAutoguide(). For restart with
Camera.StartAutoguide(r,x,y) I pass the known slit position (former guiding postion)
in x and y to the routine.

Within the field of view, astroart unfortunately again determines the guide star position
and does not use the passed x and y values. Therefore the telescope shift during
ThAr Calibration is not corrected and the star moves away from the slit.

How can I force Astroart to guide to the given x and y values and not to
do a new determination of the guide star position within the field of view?

Greetings,
Sebastian

[Forum_2016]

Hi Sebastian, I suggest you to use the command "Telescope.Disconnect" instead of "Camera.StopAutoguide()". The effect is that of pressing "Connected" button on the guide window, so the reference for the guiding point remain unchanged.

After taking the calibration lamp frame you have to send the command "Telescope.Connect" to restart the guide.

I use it routinely and hope it work also for you.

I confirm the necessity to stop the autoguide function during the lamp spectra acquisition, otherwise the telescope goes after the noise (in the meantime the star can get out of the guide window field). A possible remedy would be given by setting a threshold for guide star SNR value. It would be very useful also for normal guiding, when sometimes the SNR of a faint guide star decreases (i.e. thin cloud passage). I am wondering if Fabio could help us...

I see a "normal" guide function in your simulation, do you know the specific guide on slit function (a Fabio's great gift for spectroscopists)? Here you find a brief tutorial.

http://quasar.teoth.it/html/spectra/AA_slit_guide.pdf

All the best,
Paolo

[Forum_2016]

Interesting...
I have to ask - why take a reference frame between each sub? I usually only do it at the beginning and end of the run.
I don't use scripts (maybe I should!) so I manually re-set the slit guiding when I use the reference flip mirror....
What I think Paulo is saying and I'm thinking is that we need a "re-set" on the guiding to bring the target star back to a known X-Y position in the guide camera FOV....a scripted "nudge" function in the spectroscopic guider set-up??
Ken

------------
"Astronomical Spectroscopy - The Final Frontier" - to boldly go where few amateurs have gone before....
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[Forum_2016]

Hello Paolo
Yes, this is exactly this kind of workaround I have been looking for. Thanks a lot In principle, this solution should have been obvious.
Confusingly I did'nt see it. I tried your suggestion in a "dry run" and so far it seems to work without problems.


Well, I have already been working with slit mode for while. You are absolutely right, this is really a big help! I just saw no way to stop and restart guiding in slit-mode, which also would have been unnessary if Astroart had guided at given x and y. But since your workaround seems to works that good, I will again start in slit-mode and then just disconnect and reconnect to the telescope ... perfect

Greetings,
Sebastian