Erratic Behavior by AO-X

Hi,

I have a STX-16803, with an STX guider and an AO-X, sitting on a 14.5" RCOS.

For reasons I cannot figure out, the guide rate seems to change, for no apparent reason, from image to image. It normally will image at 4-7Hz (I almost always have mag 7-8 stars, and I have never had guiding faster than 7Hz with this setup), but, lately, it has taken to sometimes, on the same target, same filter (yeah, I know it's not imaging through the filter), no clouds at all, deciding that it's going to guide at .2Hz; mostly (but not always) it does it all the way through the exposure, then, most likely, will again become a fast guider for the next exposure, but sometimes it'll randomly start being slow in the middle of an exposure, then go back and forth for the rest of the exposure. Yup, one guide correction every five seconds. The signal is high (as much as 20k count) when it's doing this. And it is always at .2 Hz when it's not going fast.

I have noticed for a long time that it would seem to pause sometimes, but this is far more extreme.

Obviously, this isn't why I have a fast guider.

Any ideas what might be amiss?

Thanks.

Mark

 

Colin, all boxes are unchecked. I tried updating the SBIG drivers, but it won't connect to the SBIG server, saying, "Error on Connecting to SBIG Servers: 0 If you have a firewall enabled try disabling it and Download again." I did disable Windows Defender, but it made no difference (I re-enabled it after giving up). And I do have an excellent internet connection there.

[Edit] I re-booted the machine, and it now downloads updated drivers. But it refuses to install them, claiming that something else is using them. Since absolutely nothing is running on the machine, I'm flummoxed. It won't update sbigu64.sys, which is presently a 1/27/2015 version.

I just told Windows Defender to work at 9am each day; I'll check to see if it's hogging resources at night.

 

I'm up to date, except for sbigu64.sys; it will download, but refuses to install, claiming that the file is in use by another process (despite the fact that there's nothing running).

 

It turns out that I had to turn the camera off. Who knew?

It's now updated. We'll see if that has any connection with my problem.

 

Well, now the AO-X again is wandering all over the place, for no apparent reason (meaning that the guide star just makes graceful loops, generally staying in the guide box, but all over the guide box). When I switch guiding to the mount, all is well. The AO again won't move during an attempt to calibrate it in Maxim.

I'm getting the feeling that my AO-X has serious, intermittent problems (this one does have a bad history)

Mark

 

Anything?

 

We have inspected it. We ran an "exercise AO" with it off the scope, and they saw no sign of life. It's malfunctioning, so that I'm not using it (see post above from Friday night, when the AO recommenced wandering aimlessly). Can we agree that it should be sent in for repair?

Mark

 

I asked this question on private email, but Bob Denny asked that I move it to a forum. So here it is. It is just a continuation of this vexing problem that won't go away.

This continues to be a problem, almost every night—with a perfectly good guide star, it’ll go from guiding at 4.5-5.5Hz to 0.2 Hz, without warning or seeming cause (no change in sky conditions; no clouds). Always 0.2Hz. If I’m around, I can usually (but not always) get it back to fast guiding; otherwise, the night is lost. The guide star can be very bright, with each exposure over 10,000 ADU (and each exposure a small fraction of a second), and it’ll still be “guiding” at 0.2Hz.

Since the AO takes its orders from some combination of ACP and Maxim, I thought that perhaps getting both Diffraction Limited and ACP involved would be useful

I’m generally pretty good at trouble-shooting; but I have not been able to find any precipitating factor.

I did find an inconsistency in the the recommended setting for minimum guide star SNR, with ACP recommending 3.0 and Maxim recommending 50. I expect that these are not the same calculations, but, set as recommended, ACP was setting a guide exposure length that was too short to achieve a SNR of a least 50 in Maxim, which causes Maxim not to recognize the guide star ( so that it won't start the guider if this happens at the start of an image, and it won't guide if it happens during an image, if the guide star weakens a tad from bad seeing). So I've changed the minimum SNR to 5 in ACP, and slowly worked my way down from 50 to 10 in Maxim. It was at 20 in Maxim on Tuesday night, and (i) I noticed that there were a number of times when Maxim was not recognizing the guide star (seeing was awful on Tuesday night) even though it was showing up just fine in the guide box, and (ii) eventually it want to 0.2 Hz. Last night, with the seeing much better, I dropped the minimum SNR setting in Maxim to 10, and I never saw the actual SNR get below about 15; the guide speed never reverted to 0.2Hz. Obviously, I don't know if this is coincidence, or if it's connected, but there it is.

I’m wondering if either ACP or Maxim has a line of code to the effect of “if [some event], then [instructs the AO-X to guide at 0.2Hz].” I don’t believe that the 0.2Hz speed is random, since it is always the speed chosen when things go south. Somewhere in the controlling software, there has to be some sort of default to 0.2Hz.

Thanks for considering this.