The concept of stacking is to add signal while the noise averages itself out. I was able to do this with ImagesPlus software, but (with my older v5.5) I had to manually click on two stars for each image so the software could recognize the rotation. One shortcut to step around the problem is to take short exposures that do not reveal the trail, in my case 25 seconds at 200mm, then later in software, stack the images by compensating for the rotation from one frame to the next. Visually, who cares if things rotate 15 degrees in an observing session? Photographically it matters. All professional telescopes have "de-rotators" that turn the camera/sensor at just the right rate to cancel it out. It shows up when an AltAz (Altitude-Azimuth) mount track in a diagonal line but the sky rotates around the poles (see parallactic angle). Quite disappointing (unacceptable?) for a beginner of 1 month experience I would think. You can see the stars towards the edges are all short circular arcs around the center of the image. Similarly with Messier objects and NGCs: just move the cursor over to the 0 and input the number. At first I was put out that Deneb was 75 button pushes of 170, but then I realized you could type in "075 ENTER" and bam there it was. I could choose named star or Messier or NGC object with a couple of short jumps down the menus. Pretty easy if you don't kick the tripod! Next object I went to was less than a 1/4 field from center, and so it was for the rest of the night. I then went to "SYNC to target", pressed the arrows to center it, then ENTER. I chose Vega and it showed up less than 1/3 of a field of view from center of a 135mm telephoto lens. You point the arrow south, turn your scope straight up (use a level lying across the dew shield), press ENTER a few times to accept GPS values, and you're ready to "Select and slew". Although you can manage without GPS by manually entering all the specifics, having the mount lock in makes everything easier. Newer Alt-Az units (the model we have has been discontinued) undoubtedly take less time to acquire a GPS signal. As you can see in the photo, the easiest way is to use a construction bubble level in two directions rather than use the little circular bubble on the side of the mount. The mount found the first star 40 minutes after starting, though I could have saved 11 minutes by turning on the GPS right away to register satellites while levelling the unit. Having the 5 minute demo from Luca earlier in the day, I assembled it at a neighbourhood park, literally a few metres from a streetlight, which is not a bad idea for a first assembly so you can see what you're doing. The tripod is similarly robust at 17.2 lbs (7.8 kg). The carrying case is 28.4 lbs (12.9kg), of which 10lbs (4.2kg) is the counterweight (important for balancing telescopes and camera lenses to prevent grinding the drive gears). The cube is a beefy unit, a tad smaller and lighter than a car battery.
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