PHD2 will not autoguide accurately

Sequence Generator
1

When I start my Sequence, PHD2 will start and calibrate on a star no problem. Once it starts guiding the guiding is very erratic, all over the graph. If I choose to open PHD manually and start the guiding on my own it works perfect! How can I fix this?

Thanks for the help!

2

I don’t think there is a difference in auto starting the guider vs manually starting it (with the exception of possibly getting to manually choose your guide star) so I don’t think I have any advice for this. I’ll defer to @Andy to see if there is any difference between the 2 methods…

3

Correct. No difference.

Andy

4

I think I might have a possible explanation, depending on how you start SGP.

If I just turn on all of the equipment and then start SGP, load my sequence, and press the run-sequence button, SGP starts PHD2, does a slew and center on my target, “resumes PHD2” (which includes choosing a guide star and calibrating), THEN SGP AUTOFOCUSES.

This means that usually, I will end up guiding on a suboptimal star, since it was chosen before I got a really good focus. If I do an autofocus run before I press the run-sequence button, the guide star is much better and my guiding ends up being better.

So yes, PHD is started the same, but if you don’t ensure you are well-focused before you start the sequence, you may end up with a bad guide star if you let SGP choose it.

Andy, does this make sense?

Ken, is it possible to have PHD choose a new guide star after each autofocus run? Or at least do the initial autofocus before resuming PHD2?

  • Shane
5

Hi Shane, yes that definitely makes sense. It would be great for OAG users if SGP could focus before starting guiding. Maybe we need a new feature request for Ken and Jared to capture this.

There’s no way for us to know with the information provided to us whether this has any relevance at all to the original post though.

Andy

6

Thanks for the quick replies. I’ll be at th observatory this evening, I’ll check the focusing.

7

I’ve also had very bad guiding from PHD (as compared with TheSkyX) but also found the choice of GS more critical in the evening when everyone has their central heating system kicking out masses of thermals.

Try this for explanations of bad guiding, it may or may not help but should give you some useful insights:

Robert

8

PHD2 developers are interested in hearing about cases where PHD2 did not guide as well as you would have expected. You’re welcome to post your PHD2 Guide Log over on the PHD2 forum and we will look at.

Andy

9

@kor Good thought. This had not occurred to me, but very likely could influence guiding conditions. I fear this may not be a simple change, but I’ll take a look to understand the effort involved. In the meantime, it might be best to run AF by clicking the button (once before starting the sequence). Same advice for @scopehead.

10

Thanks Andy

11

Ok here is an updated. I opened phd2 without using sgp. Calibated and guided fine. Once th calibration was complete the guide star was not exactly on the gree cross hair. The cross hair instantly jumped to the guide star when calibration. Was completed guiding worked perfectly.

I then ran my sgp sequence phd2 started calibration world but the green cross hair did not jump back tje the guide star. Instead phd attempted to autoguide the star back to the green cross hair. The sequence timed out and aborted due to phd guiding error.

Any ideas?

12

You need to post your PHD2 logs along with your SGP logs.

1 Like
13

yes, I commented on the AF / guider calibration order last year - and I made a proposal to re-order the start of sequence. It clearly was a benefit to OAG users but I think at the time there was some uncertainty of whether it opened up other issues.

14

Kicking this can 2 years later, as I have the same issue.

I don’t have an OAG, I’m using a Stellervue 60mm guidescope with Starlight Xpress Lodestar X2.

I recently started using SGP. All works well however, after calibration the PHD2 guide star green box is not centered on the cross hair. It’s off center and does not correct itself. I manually stopped PHD2, then started with the same guide star and the green guide star box is dead center on the cross hairs and guiding perfectly? Resuming the sequence forces SGP to restart PHD2 calibration… rinse repeat above. Same issue.

Any help appreciated.

15

One thing you can try is to do an independent PHD2 calibration, preferably near DEC=0 and the re-use that calibration, disabling the calibration trigger in SGP. I get very good guiding and in practice I think it is better to calibrating at the imaging DEC. (You can also change the size of the little search box in PHD2, so it does not lose the guidestar.)

16

Why if you were already calibrated in PHD2 calibrate it again when SGP starts?

Heck I usualy only run a calibration when the OTA has been removed or some other drastic movement of the mount. I just rely on previous alignment.

17

This is new to me. Could you explain how to change the size of the search box in PHD2?

Thanks,

Fred

18

Fred - it is explained in the PHD2 instructions, one of the brain guide settings.

19

Buzz,

Thanks, that is a useful feature.

Fred