Ad Astra Observatory

I had moved the ST-4 to the main scope to do some periodic error testing on the mount at higher magnification. This helped me to see the errors more clearly, but also left me unable to do any DSO photography.

Also, I hadn’t rebalanced the mount since swapping in the 3/8-to-1/4 adapter, and I hadn’t rebuilt the pointing model since tweaking the polar alignment.

So I decided to do some maintenance tonight so that I can get some photography in before the moon is bright again.

While the D70 was off the mount, I popped the MPCC onto it. This required refocusing the scope, which meant some head-scratching with FocusMax before I got a good V-curve. That took over an hour. grr.

I hooked up the power cable and the shutter cable to the 300D (they run in the opposite direction from the rest of the cables, which makes things a little odd, but DSLRFocus wouldn’t find the camera. Took me a couple of minutes to figure out that I forgot to hook up the USB (image download) cable, too; I need a USB extension cable (and a free USB port — yikes). I used the parallel shutter release cable — I was worried that the 300D DSUSB would conflict with the D70 DSUSB, plus I’m out of free USB ports. At the moment, I’m using 4 USB ports + RS232 port + parallel port. That all works with the docking station so that I can just pull the laptop whenever I want. Adding the image download cable too will mean that I have to remember to unplug each time (or I need to use a USB hub).

I tabled the idea of using the 300D until I get it all hooked up. But it was good to try to start it up so that I can see what I’m working with.

Building the pointing model went fast; I’m pretty good at it. There are a very skimpy number of bright stars overhead right now. I pointed at every one I could, and only got 6 or 7. The polar alignment is improved in Az: 13′ -> 7′. El is about the same, 5′. Polar alignment is a very iterative process.

The new model put M57 (my target for the night) smack dab in the middle of the D70’s sensor (so close to the center, in fact, that the image-tweaking thumbnail in MaxIM bracketed the object — nice!).

Finding a guidestar and calibrating went easily tonight.

Because the focusing run took so long, I ended up grabbing an hour of data on M57 yet didn’t get to bed until 2am. ouch.

The rig is ready to roll now, though, with the exception of the 300D USB cable and the still-misaligned polar alignment.

I’ve decided to leave PE concerns for another day and concentrate on imaging. The autoguider is able to keep up with the errors at 2350mm, so I’m going to spend less time worrying about it.

Once I get the source of noise in the mount figured out (might be a faulty motor), I think the PE in the system is really low.