I tried to calibrate the Star Chaser, AO not in play, and found the stars are round but the exposure would indicate the centroid of the star. Calibration was hit and miss, sometimes it would indicate the move properly other times leave small red lines in no way indicating the actual move, not even at right angles to each other. If I used an extended exposure of 10 seconds (bin 1) it was more likely to properly calibrate but guiding errors was usually over 2 or more pixels. I can do far better unguided for 2-3 minutes. Not sure which direction to go on this. My pixel scale on the main chip at bin 1 is .6 arc seconds, not sure about the guide chip. The guider seems to be focused but the stars are elongated rather than round and I understand we're guiding on the centroid but expected better calibration and guiding with a very well aligned telescope. Any pointers on what would be acceptable guide error for this setup. The telescope is a 24" ASA RC f/7 w/ the AC4040BSI and Star Chaser mounted on an AP 3600GTO. I have corrections via ASCOM as I do on my 12.5" RC and STL-16803 at home.
Rereading my post I realize I was a bit inaccurate. I stated the star to be round and that's untrue. They are an exaggerated tear drop shape. On some attempts to calibrate the guider I found that the star would move but the red line was very short and at an angle, say about 45 degrees while the star actually moved straight up, then back , then left and back. The star was about 75-80% to the right of the frame and up about 1/4 of the chip from bottom allowing plenty of room for star movement during calibration. I've gone back into ACP and MaxIm and made changes to the guider such as now binning 3x3. What would be realistic error wise on this setup? I mean we're shooting at 4200 focal length with the main chip having a scale of .6 arc second per pixel and, well I'm not sure what the pixel scale with the guide camera is but larger I'm sure. I'll look up the manual but is there a preferred way to guide other than using ASCOM Direct? I appreciate the assist. I'm trying to make a list of logical steps to take to resolve/setup this system remotely. I'm already handicapped being more of a hands on guy so an accurate list of logical steps approaching an issue is really needed or I'm wasting time. Then add in a poor memory and age....I'm almost crippled.
Understood. The SC-3 you have has a 4.8um pixel size. The old STX guider was 7.4um. Scale = ( 4.8 / 4200 ) * 206.26 = 0.24 arcseconds per pixel. So you really want to bin that 4x4 or 3x3. Perhaps you could save a FITS image from the guider, and do a PrtSc and save that print screen, and then upload both here so I can have a look. Usually ASCOM Direct works fine. The alternative is to use the good old ST-4/SG-4 guide cable between the SC-3 and the mount. But then someone has to go plug it in and test it. On the Camera Control Window, Guide Tab, there is a [Move] button. It will bring up the window that has 4 direction buttons in the lower right. Put in a time like 5 seconds. Then test the move directions +x/-x/+y/-y and watch the telescope status to see increase/decrease in RA and DEC.
