OT: Has my guide camera died?

Mike Dodd

Suddenly I'm having autoguiding problems with my AP1200 and MaxIm DL 6.19, and I'm wondering if my ST-402 guide camera has gone south.

I asked about this in the MaxIm forum, but I will appreciate any thoughts or opinions from the experts here as well.

I use a separate 60mm f/5 guide scope with an SBIG ST-402 camera. Differential flexure is not an issue. This setup has guided the mount well since 2007, including in my new observatory until a couple of weeks ago.

The ST-4 autoguider cable is nearly new, and I cleaned with naptha the contacts on both RJ plugs and the contacts in the mating female sockets on the camera and the AP1200.

The AP1200 is permanently installed on a 12" concrete pier, well-aligned. Everything worked fine over the fall and spring.

The problem is that sutoguider corrections aren't applied in one direction on the X axis, and the MaxIm tracking error graph displays a gradual drift on that axis. I thought this might be caused by cables snagging, but after rearranging the pier equipment for no snags, the drift persists. I can't autoguide at all.

The latest problem is, now the selected guide star does not appear in MaxIm's guide star subframe after I click Track. That part was working fine a couple of nights ago, now it isn't.

Specifically: I exposed a full frame with stars visible. I moused-over a bright star until I found the highest ADU. I clicked that point, and those coordinates appeared in MaxIm. I clicked Track, and the subframe appeared. But that subframe contained only noise -- no star!

I repeated this five times with the same result - no guide star in the subframe. Then I gave up for the night.

Could my ST-402 camera might be malfunctioning? Every autoguider calibration in MaxIm succeeds, with a perfect L-plot on the full frame, which tells me the full frame is working and the AP1200 is responding to all four correction commands. Sound right?

In all my years of guiding with MaxIm, I have never witnessed an instance where the guide star subframe does not contain the selected star. To me, that points to something in the camera related to the SUBFRAME not working right.

What do you think? Time for a new guide camera?

Thanks for all opinions. I'm stumped.


Mike Dodd
Louisa County, Virginia USA

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