[Paul Haese]

I am using an SBIG ST-I in OAG of QSI683 with a TSA102 at f5.7 and maximDL to guide with, as well as CCDautopilot.

Last couple of nights I have seen some odd behaviour with guiding. Whilst imaging in the Milkyway star field I have no issues at all. Guiding exposures at 3 seconds, guiding optimal.

Move out to NGC300 where there at not many stars and I get star faded a lot. I can see the guide star selected but it still reports star faded in MaximDL. This is happening whilst going through CCDautopilot.

Now if I stop the guiding and click expose and then click on the guide star I get perfect guiding. No star fade.

To complicate things couple of nights ago I took off the guide camera because the shutter was not opening properly after doing a dark. I think it was power related as I plugged the USB cable straight into the computer and the shutter opened and closed.

I wonder if the USB is not getting enough power to open the shutter all the way up, as when I took the guider off the OAG the shutter was only opening by a slit of around .5mm. It was a miracle it could guide at all.

I have checked with another ST-I guider that has barely been used and it is doing the same thing when plugged in the way it was.

Would this be power or could it be some setting in CCDautopilot that is causing the problem?