Phd2

[Karlz]

Hope for some help,

I'm trying to get my phd2 going and moved the mount from Eta Carina to the running chook and phd2 gave me a note saying calibration was too far from the equator, recalibration needed. What does that mean?

Thanks in advance

Karl

[Karlz]

All good I think, I found some info about. I did get some first light finally :)

[Startrek]

Karl
Here’s some info I put together to help with getting PHD2 up and running and also while your guiding
Hope it helps
Martin

[AdamJL]

Care to share what you did to resolve this?

[Karlz]

Hi Adam,

I found this with some help from google https://openphdguiding.org/getting-help/

I clicked the best practices link and had a little read. I wasn't pointing far enough east to calibrate PHD properly. Where I was set up was close to the garage as I was more seeing if I could run my polemaster to see over some trees, then got excited that I could and set up my scope lol

[Startrek]

Karl,
Glad you resolved your issues
Did you read my attachments ?
They are a summary of key points from the PHD2 manual but in an easy to read format and only 5 or 6 pages instead of a 100 or so
Includes calibration process
Cheers
Martin

[Karlz]

I have yours saved so I can refer to them again, thank you.

[Startrek]

👍👍

[The_bluester]

The big question, and I think that I can guess the answer from your question. Are you using pulse guiding via ASCOM (And computer control of your mount) or ST4 guiding via a guder cable from the guide camera to the mount (In addition to the USB cable from the guide camera to your PC)

Assuming you are using pulse guiding and have PHD2 connected to the mount, PHD2 gets the mounts pointing position from ASCOM and if you try to calibrate at more than 20 degrees from the equator it will throw that warning.

If you are using pulse guiding and everything is working OK you do not need to re calibrate for each change of target coordinates. You can calibrate near the equator and zenith and the calibration remains good as you head toward the poles. If your gear does not change (I.E. you do not tear everything down between sessions, changing the relationship between the gude camera and main camera) you can tick the box to auto restore the calibration, calibrate near zenith and equator and then keep re using that calibration until you change something, or you think it may not be working right.

If you do not have PHD2 using a mount connection to determine pointing you need to calibrate at each change of declination (New target) as PHD2 won't know about the change in pointing and the relative rates of RA and Dec movement change when you change declination.

[Karlz]

I'm pulse guiding Paul, as far as I could work out I wasn't close enough to the celestial equator and that threw PHD out

[The_bluester]

If you are pulse guiding it will throw that message if you try to calibrate more than 20 degrees from the equator. It won’t necessarily keep it from calibrating. It is best to calibrate close to the equator, any calibration errors in how the RA and Dec rates compare may be magnified otherwise.

The upshot is though if you are using pulse guiding, you don’t need to re calibrate for each new target in a night (or sometimes for months, depending on your setup) You do need to determine though if your mount requires the option to reverse the dec after a flip checked or cleared. If you set that one wrong the guiding will run away in the wrong direction in Dec as soon as you dip over to pier east.

[Startrek]

Paul
All great advice !!

....... my attached notes, it’s all in there about calibration , how to calculate steps , location where to calibrate , auto restore calibration, Ascom pulse guiding , Brain settings , dark library, the lot !!
Sorry to be going on about it but it took me forever to get up and running with PHD2 so when I did I wrote an easy to read doc so others can get some help and at least get guiding

[The_bluester]

You have produced a very good reference for people starting out IMO.

Could I suggest a couple of changes though? An addition and a change actually. The tickbox for reverse dec output after meridian flip is a good one to mention, and there is an assistant in PHD2 that you can run to determine if you need it ticked or cleared. (Meridian flip assistant I think it is called, I am at work so I cant look now)

The other thing would be a change to the suggested min move settings. They are guide image scale dependant, for instance where your starting point is 0.2'ish pixels, mine is half that as I am using the very short focal length guider with relatively large pixels in the CEM70G. My guide scale is about 6.4 arcsec per pixel. My minimum move relates to about one third of the image scale per pixel of the main camera. I could never work out why those input boxes do not flip over to arc seconds instead of pixels when you change the display in the settings as you really need to know your guider image scale for them to make much sense.

Perhaps rather than suggesting a specific setting for the min moves, I would suggest recommending running the guiding assistant and using the min move settings it provides.

[Startrek]

Paul
Good points
Yeh I tried to keep it simple with parameters but the guiding assistant is a good reference point
Martin