The NJP is displaying some RA drift. It’s easy enough to guide out, but it’s definitely strange.

I need to gather more data. But I think that what I’m seeing is that the worm moves along its normal path but then at one point in its circuit, it jumps a large amount, then goes back to its regular path, then jumps again next cycle…

I am not sure what is causing the jump. I am also not sure whether it is a general RA speed problem, or whether it is a periodic error.

The jump makes it impossible to do unguided imaging. Since guided imaging is easy enough, I might not worry too much about it. But it is a pain for stuff like the moon…

EDIT: I have gathered some good tracking data displaying the error. It seems like the RA drift is pretty linear, with a period of 360sec. Here is the data:
NJP Tracking Log showing RA drift

PemPro needed some calibration before things would work today. Nothing major. I got it a little more dialed in. I finally figured out what it was complaining about — it thought it was supposed to do dark frame calibration in Max and I hadn’t set Max up with any darks. No biggie; it’s cool out tonight and the camera hasn’t been on long so I turned calibration off.

It’s in the middle of a 1 hour “Acquire Data” run. Looks like the worm without PEC is doing about +12/-8 in RA. We’ll see what PEC does to that.

Again, things are getting dialed in. The polar alignment seems pretty good, the autofocus is working, now I have the PEC thing in process.

I am just about ready for spring.

I had a few things to do before getting started tonight.
First, I replaced the brass worm gear with a steel one. This one is Art’s spare, which he used successfully for years. This replacement went a lot faster than the last. Things felt pretty smooth, I’m starting to get the hang of mount maintenance. Maybe.

Then I remounted the C9.25 and unwound all the cables. I do wonder if my cable harness is hurting my imaging rig. shrug.

It was a sad day; I retired the ST-4. It’s now sitting in baggies, waiting to be sold.

Once the sun went down, I spent some time focusing the new Guido (moved the camera from one 9×50 to another so that it’s rotateable).

The polar alignment is really close. I did a one-star alignment and was consistently dropping things into the 30′ FOV of the DSLR on the C9.25. Cool.

I spent a lot of time tweaking the guiding and PEC and stuff. It looks like I’m down in the ~5″ peak-to-peak range at the moment. That’ll work. On the other hand, I’ve convinced myself that I’m actually seeing the “mount’s” data as opposed to the “guide rig’s” data, as I’ve now tried 3 guide cameras (ST-4, webcam, Starshoot) on a variety of guide OTAs (from Pumpkin to Guido to Veronica), and I tend to see mount data with RMS in Y ~= 0.1, in X ~= 0.4. 0.1 is good enough for anyone, but is essentially the effects of seeing. My skies are steady enough to image. The 0.4 tends to be “not enough” for serious autoguiding. I get a lot of trailed stars, even with the autoguider running. Hmm.

I guess what this tells me is that Guido’s doing fine. The performance is as good as I’ve come to expect.

Now to see if I can tweak the PEC into shape.

I did several PEC training runs, but ended up with only 2 in the mount. I want to do a nice long run of guiding, maybe 14 worm cycles or so, then build a PEC curve off of that and load it. That would probably do the trick for settling out “what I can” from the mount’s idiosyncrasies.

Now the rig is out there running off 24x5min of M51. I haven’t done non-Ha imaging in awhile, so I can’t remember if I’m doing things right. The raw data looks a little blue. We’ll see if that means anything.

Lately it seems like I’m getting clear afternoons followed by a few cloudy hours near sunset, then a few clear hours, then it clouds in around midnight. That works. A few solid hours each night is a good thing.

It was not really clear out, and not for long, but it was enough to get some good stuff done.

I got Guido focused and gathered a bunch of guiding data, including PEC data (two runs, which I averaged).

The output of the evening left me with two action items. First, the textured finder body is not easy to rotate. So I moved the guide camera to the black finder. That means that both the finder and the guider need to be refocused, no biggie. Second is bigger. I am deciding that the brass worm migh be garbage so I am going to put the steel worm back in. This will hopefully go faster than the last time, but it is still a decently big task. Third, I want to get the C9.25 mounted up so that I cam in theory be shooting Mars while messing with the guider.

The focusing and the new main z ope shouldn’t take long, just needs to get done.

The worm will have to wait for a quiet weekend.

I love it when a plan comes together.

I picked up a new autoguider over the weekend. I also picked up a second 9×50 finder about 2 weeks ago. I only needed one more piece of gear to do something really kind of cool.

Here’s the new bit.

Sure, it doesn’t look like much. But here are all the parts, pre-assembly…

…and here’s the finished product!

Why oh why would someone want to do this?

Because this is by far the smallest and lightest guidescope around. Seriously. I have finder brackets on every single telescope (two on Pumpkin). Not to mention this guidescope never needs to be focused (no focuser!). This takes guiding to a place where I just mount up the main scope, drop on the guidescope, and go.

Pumpkin, welcome to the land of imaging-only scopes!

All hail Guido (I’ll accept either gwee-doh or guy-doh as pronunciations)! A giant among autoguiders.

it’s real cloudy tonight. But, the moon is bright enough that I can still see it, so I decided to come out and get the autoguider focused so I can try to use it for polar alignment next clear night.

It hooked up to MaxIM pretty easily; bonus!

So here’s the first photo out of the new camera. This is with Pumpkin.

Orion Autoguider first light - moon at 8 days

I picked up a new autoguider on Saturday.

If the mount is the basis of the imaging rig, then the autoguider is its closest ally. The autoguider is responsible for making a mount look good, by sweeping any errors under the rug. It’s one of those “basics” that don’t change too often, because why mess with success?

The ST-4 has been my stalwart companion for five and a half years. It’s guided essentially every image on my entire website. And it’s still going strong; The camera picks up stars, the relays drive the mount, and the camera does what I ask of it.

I have replaced everything else in the astrophoto rig; mount (4 of them), guidescope (2), main imaging OTA (six), imaging camera (3), and countless extra doodads, while the ST-4 just kept on trucking.

The new camera is an Orion Starshoot Autoguider. It’s small and light, and I got very used to the concept of centering and finding guidestars in realtime in the past week or two when I’ve been using the webcam as a guider. USB makes a big difference, as will the 1280×1024 chip. Faster downloads might mean better guiding.

I’m not ready to give up the ST-4 for good yet; the astronomy gods are currently exacting their revenge over the purchase, so the Orion camera hasn’t seen the sky.

But the handwriting is on the wall. There’s been a changing of the guard.

Long live the Orion Starshoot Autoguider, and long live the ST-4.

My autoguiding system is so broken right now.

The OAG really complicates the task of finding a guidestar, because among other things, the OAG is very difficult to get to, so I continually find myself trying to jam the guide camera in between the OAG and the finder, for instance. I am finally finding guidestars with it, but the ST-4′s small FOV and mediocre sensitivity is also a real drag.

I didn’t want to have to redo my whole pointing model by remounting Pumpkin (and the attendant rebalancing, etc. that goes with that). So my “guidescope” sits around gathering dust while I struggle.

I finally decided that I needed to figure out how to get the webcam working as a guider. This has its ups and downs — with a maximum exposure length of 0.2s, the webcam is only picking up the very brightest stars. On the other hand, I can sort of sweep around and find guidestars with the webcam in “live” mode. So that’s kind of nice.

So the OAG + webcam is the worst possible case: a limited selection of stars to choose from, and a very insensitive camera with which to find them.

I suppose what I really need is live mode for the ST-4. I doubt that will happen. So I need to figure this out some more.

In short, I had 4 hours of clear sky tonight, and I have a pointing model (and a focused camera) to show for it.

grr.

Time to upgrade some stuff.

I finally lost patience with my Meade reticle eyepiece. It’s the eyepiece I use the most, but it’s designed for people who manually guide; the reticle is adjustable. This “feature” means that for the normal use I put it to (centering things in the FOV), it really sucks.

Celestron’s unit has double fixed lines, and is compatible with my current illuminator, and I found it on clearance, so I have one on the way.

While that’s coming, I decided to pick up another finder dovetail base, because I have a plan to convert a 9×50 finder into a guidescope, and I’ll need a base to mount it up.

I have the 9×50 “soon to be guidescope” finder on the way, too.

Also, since I am probably going to be using Pumpkin as an imaging scope and not so much as a guidescope (at least, not in the near future…), I ordered some 3″ scope rings. That way, I will not have to worry about orthogonality with the guider rings that Pumpkin is currently using.

Finally, I have noticed that my 1.5″ extension is not quite right for plopping eyepieces into the focuser, so I picked up a couple of 2″ parfocalizing rings, so that I can set it up properly.

whew. Time to go through my gear and sell off some unneeded junk of yesteryear.

How to make an eFinder from a 9×50 finderscope, in several easy steps.