On-Axis guider vs. Off-Axis guider

[SCO]

I have heard that an on-axis guider is better for exoplanet work than an off-axis guider.  The reason given for this that with an on-axis guider the guide star is closer to the target and comparison stars, and therefore the effects of any polar misalignment are reduced as compared to the off-axis guiding approach.  I am interested in opinions from this community about this argument.  What do current exoplanet experts use today?  What would this community recommend (off-axis or on-axis)?  Does anyone think that it makes a difference?  Thanks.

[Riccardo Papini]

Hi Ed,

I am not a professional; only an amateur who attended the AAVSO CHOICE Course with Dennis Conti, chairman of the AAVSO Exoplanet Section. I strongly suggest attending it, if you had not so far.

Coming back to your question, at the link here below, you will find "A Practical Guide to Exoplanet Observing" where Dennis Conti describes the most common approaches to auto-guiding and their pros and cons (section 4.4).

https://astrodennis.com/Guide.pdf

Riccardo

[SCO]

Thanks!