I finally got to test the Mini Tower autoguiding feature last night. I set up at the Heart O’ Texas Observatory just north of Abilene, Texas, owned by Bob Terrell. It was 103F, 18% humidity, and gusts of wind between 3-12 mph and a clear sky. Not bad for West Texas in July.
I did a couple of polar alignments and settled for 17.6′ high and 23.4′ West. Not a very good alignment, but I was more interested in seeing the autoguider in action. I started imaging M31 around 10:30PM. I set the Autoguide selection to 0.4 sidereal in the 8401 handset. My autoguider is an Orion Starshoot DSCI II, and it is not supported by PHD Guiding, so I had to use the Maxim DL Essentials software that came with the camera. The interface between the camera and mount was the LX200 protocol in the software drop-down box. I had already spent about three days fooling with the GotoNova ASCOM driver, which runs PC planetarium programs, but is clueless about pulse guiding.
The DSCI had no trouble finding a guide star. It smoothly ran the calibration sequence. Then the frustration began! I had the aggressiveness set about midway; 5 on both X & Y axis. Not good! Big pixel errors within a few seconds, and my image was jumping all over the screen. It took about 45 minutes to dial in some acceptable parameters. I ended up setting the aggressive factors to X=1, Y=1. I could get about 5 or 6 minutes of really good guiding, and then the pixel errors would get so big I would have to reset. This wasn’t “set it and forget it”. I think my problem was in the polar alignment. Wind was also a factor. I will test the same rig this weekend on my GM-8. Maybe that will shed some light on the problem.
I imaged M31 and later a widefield study of Scutum. All my exposures last night were at 120 seconds. I previously found the unguided limit around 90 seconds a few weeks ago, so this was an improvement.
M31 Andromeda Galaxy 15X120 sec exp
Scutum Widefield with M11 and Barnard 111 5X120 sec exposure
I became adept at manipulating the autoguider by 2AM. I just had to stay on top of the pixel error. I kept the errors around 0.30 to 1.25 and the stars were quite round as a result.
The moon rose and a thin cloud cover rolled in from the North, so I shut it down around 3 o’clock. I was pleased with the way it went last night. I think the Mini Tower can be a great AP platform in EQ mode with a little experience.
John Bozeman
12:41 am on July 17th, 2009 1
YEEEEEEHAAAAAAAAAAAAAAAAAAAAH!!!
John has proven that it can be done! All it takes is BELIEVING!!! Don’t tell US it can’t be done! WE’LL tell YOU when it can’t be done!!
Steve
9:30 pm on July 22nd, 2009 2
John,
I am impressed and am trying to follow in your steps. Can I ask you for a bit more detail with respect to the AG link to your mount?
I think you may have plugged the AG into the port on the MT? If so how do you control the AG? Or did you plug the AG into your computer and that into the MT?
Also as I look at your pics you seem to have the scope on top of the MT, like a “true” EQ mount, with counterweights below. Is that the configuration you use? I have had trouble when I use the MT with scope on the “side”. Can you help me with this? Thanks, Stan