MaxIm not reporting correct value for MultiStarGuiding [workaround & bug filed]

[Samuel Lising]

Hi.

I've just begun setting up ACP and scheduler at my remote setup at Sierra Remote Observatories and have run into some issues with ACP and guiding.

My hardware setup:
AP 1600
AP 130 GT
SBIG STT-8300 with FW8G-STT

Software:
APC 7.2a
Scheduler 3.7a
APCC
M1 Weather Watcher
Maxim DL 6.07
Focus Max 4

The issue I have is that guiding seems to only work intermittently. With the targets that I have entered into Scheduler, early in the evenings ACP seems to be able to guide properly, both before and after a meridian flip. However, for some reason my target later in the evening don't seem to be able to acquire guide stars properly and the plan fail. It's been rather bad weather over the last few weeks and I have only had a few nights to test but I believe what I am noticing in Maxim's guide log is that the guide stars are drifting for the targets that fail. It's strange that guiding would work on both sides of the meridian for some targets and then drift in the wrong direction later on in the evening for other targets.

this is the log message:
09:52:51 Updating pointing...
09:52:51 (taking 5 sec. exposure, Clear filter, binning = 3)
09:52:51 (using Raw readout mode)
09:52:51 (starting exposure)
09:52:59 (exposure complete and image downloaded)
09:53:00 Image finished
09:53:00 Plate-solve pointing image.
09:53:00 722 image stars found
09:53:00 886 catalog stars found
09:53:01 Solved! 229 stars matched.
09:53:01 Average residual is 0.4 arcsec.
09:53:01 Pointing error is 0.266 arcmin @ angle 275.55
09:53:01 True focal length is 862.5 mm.
09:53:01 True binned plate scales (arcsec/pix): H = 3.87 V = 3.87
09:53:01 True image center (J2000): 07h 04m 13.9s -11� 18' 21.46"
09:53:01 Imager sky position angle is 31.6 deg.
09:53:01 [sync] telescope synced
09:53:01 Within max error tolerance, no re-slew needed.
09:53:01 Target is now centered.
09:53:01 (long exp, no orbital tracking, trying to autoguide)
09:53:08 (guide star SNR=97.8 X=165 Y=126)
09:53:08 (initial exposure interval 2)
09:53:13 (guide star SNR=49.4 X=165 Y=126)
09:53:13 (final exposure interval 2)
09:53:17 (guide star SNR=44.3 X=165 Y=126)
09:54:32 (guide star SNR=79.0 X=297 Y=28)
09:54:32 (initial exposure interval 2)
09:54:37 (guide star SNR=70.7 X=297 Y=28)
09:54:37 (final exposure interval 2)
09:54:41 (guide star SNR=59.3 X=297 Y=28)
09:55:57 (guide star SNR=46.8 X=171 Y=102)
09:55:57 (initial exposure interval 2)
09:56:02 (guide star SNR=38.4 X=171 Y=102)
09:56:02 (final exposure interval 2)
09:56:06 (guide star SNR=43.0 X=171 Y=101)
09:57:21 (guide star SNR=42.3 X=172 Y=99)
09:57:21 (initial exposure interval 2)
09:57:26 (guide star SNR=40.1 X=172 Y=99)
09:57:26 (final exposure interval 2)
09:57:30 (guide star SNR=45.1 X=172 Y=99)
09:58:40 **Autoguiding failed.
09:58:40 (**AG failed for aggregate exposures and external guidescope)
ACP console log closed 24-Dec-2014 09:58:40 UTC

I've tried 2 methods for calibration - first with ACP set to "rotated off axis pickoff" with the guide sensor rotation set at 0 degrees and the calibration executed through ACP. The second method I just calibrated Maxim and had ACP set to "no rotator (all types)". With both methods I calibrate pointing to the east. I have found that with the second method I can't calibrate from ACP because the ACP calibration process slews the telescope to find a guide star, but it is based on the field of view of the main imaging ccd and not the guiding field of view. But as I understand it - as long as maxim is calibrated properly, it shouldn't make a difference in ACP. In both cases I have had the same results, being able to guide on my targets early in the evening and then failing with targets later in the evening.

I have maxim set with the "pier flip" setting off and "on pier flip" set to "do not change". In all the scheduler plans I have dithering set to -1 (auto). I am wondering if one of these settings might be the problem. In my past software set up I have found that I needed to reverse x on pier flip, but as I understand it I do not need to set this when running ACP. Is this correct? Maxim is also set to use multiple guide stars. I believe I had tried in the past to just use a single guide star with the same result (I can't be certain that I tried this. The days of weather delays extends beyond my usable memory)

I also have APCC with "enable pointing correction" on and "enable tracking correction" on. I've been able to guide in maxim with these settings so I don't think they are the culprit.

I'm including attachments of the guider and imaging session log files. You will notice that the first 3 targets were acquired successfully (M45, IC434 and NGC2264) after that all the remaining logs show the same guiding error. If you look at the maxim guide log you will see that the failing targets have x and y errors that seem to be drifting in the wrong direction.

I saw an earlier thread a similar issue with intermittent guiding results and replacing the SBIG plugin in Maxim seemed to solve the issue. I've checked my plugin and it seems to be a more recent release that the one that was posted.

I'll probably try to play around with the pier flip and dithering settings when I get some good weather again, but I'd like to know if anyone with a similar set up has had a issues with guiding such as this.

Thanks.
Sam