Centering using Plate Solve 2


I am still trying to get all my software and equipment working together. Right now I am stuck with PHD2, but I also have another bit of difficulty.

This has to do with my intended target being, instead of the center of the frame (I am using a Canon 600D for getting things set up and working together), the target is invariably way off to either the right or left of the photo.

From what I understand, Plate Solve 2 requires you to enter J2000.0 coordinates, which apparently does not work well at all.

My PHD2 is calibrated on Polar Alignment to within less than 10 arc seconds on both axes, so I do not perceive that as the problem

Whenever I use my other software, BYEOS, PHD2, and AstroTortilla. my centering is ALWAYS spot on.

I get the feeling that somewhere I am missing something in my setup of SGP, and that is causing an error.

Additionally, whenever I run a sequence, where SGP tells PHD2 to calibrate, that calibration “ALWAYS” fails. If I run PHD2 by itself, it never fails to do a calibration sequence. So, again, something is not working properly together.

I really wanted to use SGP, as it can control my two Canon cameras, and also my two ZWO ASI cameras. I have just started wanting to try narrowband photography, but if I cannot get SGP to work with all my other software, regardless of how I set up my profiles, I will never be able to do so. I’m kind of frustrated right now. I’ve spent the past week trying to work out just why PHD2 will not calibrate when SGP directs it to.

I know I haven’t provided much information, but maybe someone can tell me just where in the software I need to look, in case I have missed something.


Giving some more information will really help the community help you.

Which mount are you using? How much backlash do you have?

Which method of guiding are you using ST4 or Ascom pulse guiding?

If you use Ascom pulse guiding you need not re-calibrate with every target or sequence if your optical train doesn’t change, ie tear-down each session. The PHD2 calibration settings can be saved for use at the next sequence saving a re-calibration moreover the calibration is adjusted between targets of differing altitude too. You also get to save on one cable.

For setting up PlateSolve2 have you tried the help files link here?




Barry, I am using the ASCOM way of doing things, just the one cable. My mount is a Celestron CGEM DX. I use an ES102ED with an Orion SSAG mounted to an Orion 50mm Helical Guide Scope. I have a fairly fast computer, using an I7 processor with 8mb of RAM, so processing power probably isn’t the culprit. I am using the most recent editions of ASCOM, PHD2, etc

I set up my equipment in SGP with the Equipment Profile Manager, and I am guessing that might be where I am making my mistake(s).

I know that when I tried setting up my Plate Solve 2, the difficulty in getting it to work was because of one thing, having both catalogues attached. It apparently cofused the plate solve program, causing it to run forever, and finally failing. PHD2 is doing a similar act. Instead of doing 12 step calibrations each direction on each axis, it is going into the 20s to 30s, finally failing. But, as I mentioned, if I run PHD2 with my other imaging software, or alone, it calibrates as it should.

I just looked at the link, and yes, I follow it just as written. Plate Solve 2 works now, but my PHD2 is not working the way it should be when SGP controls the calibration session. I get the feeling it is something to do with the parameters in the Auto Guiding Equipment Profile, or possibly something in the pop up window you use for the Sequence. Those are the only two windows I know of that deal with PHD2 control. Are there any others?


Here’s where that setting is located in PHD2:

You really don’t want to be calibrating during your sequence run for the reasons you are finding. Calibrate once near declination zero and within an hour or two of the meridian. Do this before you start your sequence as part of your setup procedure at the start of the evening (you can do it before it is dark enough for imaging.) If you leave your guide camera in place in the guide scope or OAG and do not rotate it, then you do not need to calibrate again. Your calibration remains valid from night to night. Even if you have to disassemble your rig, you can mark the barrel of your guide camera with a piece of tape so that you insert it at the same angle, then you don’t need to calibrate the next time you setup either. The only time you need to calibrate is if the guide camera rotates, or if something significant changes like you use a different guide scope, or if you change the mount’s guide speed setting.



Andy, Thanks so much. I will check that, if I can ever get SGP running PHD2 to complete a calibration. I still cannot understand why I can get a good calibration when using PHD2 directly, but when I have SGP control PHD2, it refuses to calibrate, and eventually just quits trying, and ends the sequence.

Can I calibrate outside of SGP, and somehow save that calibration to my sequence for later use? Right now I have both the plate solve and PHD2 equipment for my current test sequence left off, and am only trying to use my mount and camera equipment in that sequence.

But I didn’t purchase SGP to just find a way to work around some kind of glitch that I probably am causing. I really would like to figure out just where I am inputting incorrect check marks or other information.

Unfortunately, I still do not know how to take a screen shot with my Windows 8.1 computer. I was told how to do it with my WIndows 10 computer, but it seems the procedure is different. And I use my Windows 8.1 computer for my astronomy, as for some reason, it seems to do calculations quicker than my Windows 10 computer, which actually has twice as much RAM. The processors in both computers are I7’s. But the W10 speed is 2.6GHz and W8.1 is 2.4 GHz. Still cannot figure out why the faster computer is slower overall with number crunching.

Anyway, back to the settings in SGP. Does anyone know what the best settings are for the auto guide section; which boxes should be checked, and what figures should be in place. Here’s my equipment.

Explore Scientific ES102ED for my OTA
Orion Mini 50mm Helical Focuser Guide Scope
Canon 600D, Canon 7D mkII, ZWO ASI 174MV Cooled and ZWO ASI 1600MM Cooled (w ASCOM Driver)
Filter Wheel is an Atik EFW2 for 1.25 filters (all Astronomik)
Auto Focuser is a Moonlight version with mini controller
Celestron CGEM DX

Software programs are: SGP v., plus both Plate Solve 2 catalogues (APM being used)
PHD2 v.2.6.1
ASCOM Platform 6.2
Current Celestron ASCOM Driver
Microsoft .NET Framework 4.0
Stellarium and Stellarium Scope (which I use to do my initial slew) Local Solver

                                AstroTortilla when I use BYEOS with PHD2

A lot of this is probably extraneous, but I listed all the astronomy software I could think of. Maybe this list will help someone figure out why my SGP cannot do a proper handshake with PHD2


What @Andy is saying is that this interaction is not necessary… Calibrate outside of SGPro and when SGPro makes the request to start guiding that calibration will just be used. Having SGPro calibrate is really only useful when using ST-4 and changing targets that have a considerable deviation in DEC.

We would need to see logs here to try and understand why you are not converging.

While this is true, it’s also worth pointing out that any location entered in SGPro must be in J2000 (regardless of whether or not you are using PS2).


Ken, Yes, I intend to do some more experimenting tonight. Since I am still trying to get SGP to at least run my camera, I am not going to set the Equipment Profile for my Sequence to anything but that.

What I intend to do is open BYEOS, slew to my target with Stellarium, calibrate with PHD2, then use AstroTortilla to center on target.

But the problem is when I start using my ZWO ASI cameras. I have no other option for Plate Solving outside of SGP when I do use them. I guess I will have to figure out how to get around whatever the glitch is between SGP and PHD2.

By the way, I use ASCOM SSAG Guide Camera. I could never get things to work when I had the ST-4 cable connected.

If I finally find success tonight with the Canon camera using SGP, then my next try will be trying to use my Colour ZWO ASI camera, which I will have to figure out how to slew accurately to the target without having PHD2 involved.

For now I am at a standstill in my progression through SGP. I’ve tried one step at a time with each piece of equipment. This means I have not been able to work with my auto focus or my filter wheel, and as a consequence, will have a long wait until I can start narrowband imaging with my ZWO ASI 1600MM Cool camera.

So I may be back for help with both my focuser and filter wheel setup. I am the type that needs lots of help. I don’t understand a lot about computers or their programs. It’s like an alien language to me.


That is what Ken and I have been trying to answer. Sorry our answer was not clear enough. Here’s what I recommend:

  1. start PHD2. Open the brain and check the “Auto restore calibration” option I indicated in the screenshot in the previous post. You only need to do this once.
  2. connect your equipment in PHD2. slew the mount to a location near declination 0 and within a couple hours of the meridian. Nudge north a small amount to take out any dec backlash.
  3. loop exposures, select a bright star, then click the guide button. PHD2 will calibrate. PHD2 is now calibrated and you never need to calibrate again unless your configuration changes as described in the preceding post.
  4. In SGP, make sure this option is not checked

Once you have it setup this way, SGP should never trigger a calibration in PHD2.



Sorry if I’m a bit dense. But, yes, I really couldn’t wrap my brain around what was first said. I went to Stellarium to visually see what you were talking about. Yes, I need to see something like that to visualise things.

I’ve entered the checked boxes, and only need to do the calibration your instructions suggest. Thanks. I sure hope this solves my difficulties


I was totally floored when I went out, and tried calibrating like you said. Well, it seems the software remembers last night, and so far, tracking has been spot on, regardless of where I point. I’m doing some test exposures to check for tracking accuracy. Right now I am using BYEOS for the test, but tomorrow, I will try SGP, and see if it accepts the calibration. Sure would be nice to get off PHD2, and start into my auto focus with filter wheel.