Help please with PHD auto-guiding setup

[cfpendock]

I have been trying without success to set up an autoguiding system using a Celestron CPC, guided by a DMK camera and a piggyback 80mm refractor, and using PHD guiding. The autoguide port of the CPC is connected to a PC via a Shoestring GPUSB connector.

The problem is that because it is always cloudy, there is rarely an opportunity to see the stars, and so in order to save time, I thought I would arrange for a "false" star, made up of a lightbulb inside a box with a pinprick on the side. This false star is positioned at one end of a long and fairly dark barn, about 20 m from the scope, and just possible to focus.

PHD accepts the mount (GPUSB), camera (windows WDM-style webcam camera), and tells me it has found the telescope. I set the scope up in Eq north alignment, and I can get a good image of the "star" on PHD. But when I select the star, although the on-screen box tries to follow it, it doesn't seem able to keep up, and eventually gives up, flashing red at me.

The scope is not wedge mounted for this exercise, and therefore is only moving in a horizontal RA. But because I have it Eq north aligned, it is actually moving at around sidereal rate, and therefore the "star" is appearing to move quite quickly across the screen.

Could it be that the scope is moving too fast to keep up? I have adjusted it's auto guide RA to 99% of sidereal, but PHD is losing it too quickly. In fact I am not sure that PHD is moving the scope at all.

I have run the GPUSB checker, and with this I can move the scope, so I presume it is connected OK.

Do I have to wait for a real star to check this system out? Could be a very long time here.....

Chris

[badgerchap]

I had a similar problem, but with a real star, so that's not very encouraging :/ Like you I will have to wait for some more bona fide stars!

[Merlin66]

The target star may be just moving toooooo quickly for your trials.

If you have a laptop available, try:

http://sweiller.free.fr/SGE/SGE-star-guiding-emulator.htm

[cfpendock]

Thanks Merlin. That looks good. I think I may have to give it a try, maybe borrow someones laptop for the target - I don't think screen split would be so good.

Chris

[Gasman]

Thanks for that link Ken, should help with setting up autoguiding with AA5!

Regards

Steve

[AstroAndy]

Have you tried experimenting w/ the calibration steps, with "force calibartion checked in Advanced settings and exposure time (maybe between 500-750ms on cal. exposure time 3 seconds)?

[r3i]

The target star may be just moving toooooo quickly for your trials.

If you have a laptop available, try:

http://sweiller.free...ng-emulator.htm

Great find, looks like an interesting piece of software - thanks for sharing