Getting Started
Step 9: Autoguiding Overview

Autoguiding is the number one barrier to effective astronomy, automated or not (unless you only take short images). We've provided a lot of information in Auto-Guiding Your Mount, including a couple of papers, one from Jim McMillan, a world-class guiding expert, and one from us which is a detailed engineering paper on autoguiding including rotated modes. Before diving into all of that, however, we'd like to provide you with a few things that will help you get guiding working with ACP.

• It is essential that you have guiding within MaxIm DL working reliably with your setup before trying to use it with ACP's automation. There are many settings in the advanced guider setup windows. Getting it right can be a bit daunting; just be aware that guiding is complex and getting the parameters right is just part of the fun.
• If you are pulse-guiding through the telescope (as opposed to using guiding relays) be sure to select ASCOM Direct in MaxIm. Do not use "Telescope". If you do, then MaxIm's own (simplified) observatory control features can become active and confuse things with ACP. Do not connect MaxIm's Observatory Control to ACP's hub or the telescope, period!
• You also must calibrate your guider once as described in the section Calibrating the Guider. With ACP, it is not necessary to recalibrate the guider unless you change your optics or guiding imager, even if you have a rotator and maybe an Adaptive Optics unit! Of course, you'll need to recalibrate any time you change your guider optics or guiding imager.
• For internal and off-axis guiders, you absolutely must have a planetarium with an accurately scaled field of view indicator.
• If you have an SBIG or StarlightXpress adaptive optics unit, see Using Adaptive Optics.
• If you have a camera rotator, see Using Rotators. This is the most complex configuration so don't try to slide by!

Essential Facts

• With a German EQ mount, guider calibration must be done looking east.
• You don't have to recalibrate the guider (unless you change something). ACP manages it through GEM flips and rotator changes.
• You must supply ACP with the guider's plate scale (arc sec per pixel) in order for dithering amount to be correctly calculated in main imager pixels.
• There is no need to have the imager lined up with the mechanical zero of the rotator. You can just slap the imager into the rotator at any angle and forget it. ACP will work out the difference between the mechanical and sky PA.
• If your rotator slips while observing, you'll see this in the logs. Look for "PA error, correcting" messages. If you see these, you have an electromechanical problem with the rotator.

The common guiding configurations are

• External Guide Scope: A separate optical unit and sensor, mounted externally to the main imaging system.
• Internal Guider: A small guide sensor mounted inside the camera body adjacent to the main sensor. Small field of view.
• Off-axis guider: A separate guide sensor unit which picks up light at the edge of the field via a pickoff mirror/prism in the light cone.
• Rotator: A device which rotates the imager body and/or the off-axis pickoff, allowing for internal or off-axis guide sensor to be moved around the main sensor. This is virtually essential for internal or off-axis guided systems to allow a reasonable degree of freedom in guide star choice, especially German mounts which flip.
• Guide Relays versus Pulse Guide: The method by which the guiding servo makes small changes to the mount's pointing to correct pointing errors during guiding. If you use guide relays, do not connect MaxIm to the telescope (MaxIm Observatory Control). If you use pulse guiding (though the telescope driver) select ASCOM Direct in MaxIm (not Telescope). Do not connect MaxIm's telescope in its observatory control.
• ACP's Guiding Configuration Selector: Note that for external guide scopes,

Next Steps

You've only scratched the surface.

• As soon as you can, start using ACP's web interface. We are constantly striving to make it as good as we can. Learning with the web interface means that, whether you're in your observatory, in a warm room a hundred feet away, or using your tablet in a hotel room a thousand miles away, one set of controls is all you need to learn.
• If you are in a run of bad weather or just want to learn offline, set up Simulation Mode and practice doing runs through the web browser.
• Once you've gotten some runs under your belt, have a look at the Standard Scripts page for info on the myriad of tools that come with ACP.
• You should become familiar with ACP's automatic sky-flat feature.

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