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Lodestar-OAG weak stars issue.


ollypenrice

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Hi All,

Not having much luck at the minute. Both imaging camera and guide camera have problems which are probably unconnected but who knows? They started at the same time but that can be misleading.

The setup is permanent and hasn't been altered.

The Lodestar is working through an SX OAG ahead of the SX filterwheel and H36. It seems to be working normally except for the fact that it is hardly registering guidestars at all. If you can see them at all they are very faint and can't be held onto even with 5 second subs (which the mount likes.) I've played with the screen stretch and they always look dim, wherever I look in the sky. You would just say that there must be some thin haze or cloud but there isn't. The sky is perfectly clear for the 16th consecutive night. I haven't moved the OAG or focus since the guider was working perfectly. I'm guiding in PHD. Could there be a setting that I've inadvertently altered or has reset itself? I don't know it well.

The imaging camera just keeps losing connection with Nebulosity so that's probably a poor power supply or something. I'm confident I can sort that but the Lodestar thing seems really bizarre. Any ideas? I presume low voltage (I run on the mains) would just kill the Lodestar, not lower its sensitivity?

Olly

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I assume it has to be something as simple (!!?) as the connections or power.

As you know the Lodestar sensitivity, for guiding, is probably as good as it gets.

(Just check the pick off prism, if you can...I have found occasionally that it can fog up..)

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Hi, id second the suggestion that it's the USB. With my lodestar i get perfect images with no extenders, a dim signal with one 5m active extension and none with 2. Also with my qsi I'd get random disconnects in maximdl if I used just an active extension. A powered hub sorted both problems for me for up to a 5m extension. I'd suggest just plugging your laptop in with no extensions to see if that sorts the problem

Ian

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If I move my SXOAG+SXFW+SXH16+SXLodestar stack from my refractor to my SCT, the guide image FOV and star intensity is very different. The ED80 is 384mm, F/4.8 (x0.8FR) and the SCT is 1280mm F/6.4 (x0.63FR). In this SCT configuration the OAG is virtually unusable without moving the prism. If I use the stack on the SCT with the same x0.8FR as the ED80 setup I move to 1625mm F/8 and the OAG image is much better. I find I can now guide with either scope very well if I use a common imaging stack with the x0.8FR.

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If I move my SXOAG+SXFW+SXH16+SXLodestar stack from my refractor to my SCT, the guide image FOV and star intensity is very different. The ED80 is 384mm, F/4.8 (x0.8FR) and the SCT is 1280mm F/6.4 (x0.63FR). In this SCT configuration the OAG is virtually unusable without moving the prism. If I use the stack on the SCT with the same x0.8FR as the ED80 setup I move to 1625mm F/8 and the OAG image is much better. I find I can now guide with either scope very well if I use a common imaging stack with the x0.8FR.

Thanks. That seems reasonable since the angle of the light cones will be different in each scope. I think what must have happened to us is that the OAG got inadvertently moved up a bit. I have made a strut to support the camera top since it had more flexure than five guidescopes put together as supplied. This may have pushed the OAG up a bit. I was back to good guide stars last night and with the shorter subs that this allows it beocmes realistic to diither again, something we very much want to do.

Olly

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