Autofocus, Plate solving, and guiding


I’ve been playing around with a trial copy of SGP for 6 days and have run into a situation a couple of times.

When the sequence starts, SGP slews the telescope to the target and runs plate solving to center. One issue I had was that my telescope was not in focus yet meaning that I only had a few stars to work with and plate-solving failed. Wouldn’t it be better to run the autofocus routine before the centering routine?

The other issue I had was a slightly off balance OTA was causing streaks in the image. Obviously, this isn’t SGP’s fault and it definitely needed to be corrected before continuing but, I would think that activating guiding before platesolve capture would have helped a great deal because I could have received a message from PhD chiming like there’s no tomorrow before I commit to a few minutes of platesolving a half billion little streaks.

I also wonder if a skip option could be added to the sequencing. For instance, a couple of nights ago, I had built a sequence to run overnight with multiple targets. Well, one of my targets was in the trees when SGP started on that target’s events. However, the next target in the list was available and could have the option to run while the other target had some additional time to clear my neighbor’s forest. I would think that you would want this on a per-target basis so, if the target can’t get a lock, maybe in some situations, I want it to retry every ten minutes until it’s ready and other times, I want to skip it and just read a dialog box in the morning.

At any rate, pretty cool software you’ve got there.


No. The auto focus routine requires you to be roughly in focus when it runs the first time and if you’re roughly in focus you’ll be good enough to do plate solving. You can add ‘notes’ that pop up when you start a sequence; I specifically have in mine to ‘check focus’ and ‘slave the roof to the mount’ to ensure I don’t miss those steps prior to starting.

For your second question about being in balance and streaking images, you would find that guiding would solve your problem. Or, put in a proper settling delay (it’s on the telescope tab) to ensure you don’t have this problem. SGP assumes you’re operating your equipment properly (it’s balanced, you’re in focus when you start).

The ability to set up targets based on altitudes has been brought up and it’s in the hopper for inclusion at some point. As of right now, the only way to prevent something like this is to figure out when the object drops below your horizon (whatever defines that, trees, etc) and put in an appropriate time for that.

You can have SGP run a recovery mode (re-attempt centering/guiding every x minutes for x minutes). But, it wouldn’t help in your case. It’s mostly useful for the stray cloud that interrupts images.

I’d recommend really reading the manual a few times along with several of the tutorials (I’ve installed SGP… what now). They’ll help you get the most out of your installation.

Good luck,