wimvb

I want guiding like that! At 0.4 " rms, you don't have much of a problem. Guiding rms is the same in dec and ra. It might have been wind previously, but that would probably have resulted in a less regular oscillation. Btw, here's my go at your data. I had trouble with the colour. Maybe it's my processing, because I'm not used to combining data from several sources. Now I must go back to my own M94 data.

Yes it does.

Unfortunately, we can't see that from the image. The satellite could have shot through that frame in a fraction of a second. That's why you'd need a short exposure, where, for example, when you start the exposure, the satellite is inside the frame already, and it still is when you end the exposure.

I thought of that, but that would only result in intensity variations. The wiggle you see, would be miles of amplitude for the satellite.

These simple, geared dc motors have lots of backlash, so you can't go back and forth between filters too much. And to be honest, if the hitec device also works with steppers, you might want to upgrade the motor at some point. Edit: just found out that it's a dc motor controller

I see you have motorfocus on your telescope, albeit a simple one. SGPro allows focuser offsets for various filters. If you don't switch filters too often during one session, you should be able to use that feature. Those exposures may become very short, depending on the satellite. How fast does a (non geo-stationary) satellite travel across the sky? The fov of a 10" may be too small. Anyway, a guide log should also provide information.

Ok, a last quick one: I briefly inspected the R, G, and B masters and it looks like the red master has the tightest stars, followed by green and last blue, which has the fuzziest stars (small stars). Do you refocus between filters? With the ED80 you probably have to do that. Now I'm really off to bed.

Here's a quick combination of the pre-flip and post-flip images. The more vertical satellite trail is pre-flip, the more diagonal is post-flip. It seems to me that the wiggle is slower pre-flip but also a little stronger. The guide log will probably tell us more. Maybe also the frequency of the vibration. That's it for me for the night. I'm off to bed.

Btw, I'm working on your image. I'm having a bit trouble with the colour, but the L is a pleasure to work with. You've got great detail. Here's what i got so far. (click on the image to view full size)

I think those satellite trails are an indication. They wiggle somewhat in the same direction as your star elongation, because the wiggle has a saw tooth shape. It seems to me that you have a vibration. A guide log may tell you more. Also, check for satellite trails in any post-flip subs. Do they show that same wiggle?

But unfortunately, not a quick fix. Since the elongated stars are only before the flip, why don't you just stack those subs, to isolate the problem? Or post a single sub.

PixInsight's image solver to the rescue

If the elongation is along RA, it's tracking/balance. With most mounts (generally not the high end models, and maybe not belt driven either) having the scope slightly East heavy, keeps the gear engaged and improves tracking. But East heavy before a flip becomes West heavy after, and vice versa.

Very nice image. I'm surprised that your camera didn't pick up the Ha signal near the core. It is very strong in my data. My guess is that this is a balance issue. The scope may be West heavy pre-flip and East heavy post-flip, ie you have to adjust the counter weights slightly outward.

My take on this data, LHaRGB.

"Up here", the nights get so short so fast, that it just isn't practical to do any imaging when there's no longer any astro darkness. I noticed the difference when I tried to stretch my luck by a few nights. Absence of darkness means that the noise increases fast. So you have to compensate by taking more exposures. Which are more affected by the increased light. Which in turn means you need to take more exposures still. Which ... (I think you get it by now).

+ F4.7: slightly easier collimation, probably + F4.7: ever so slightly smaller secondary. This should give you a little more contrast. But probably not enough to notice in the field. + F4: slightly "faster", but only because you sacrifice pixelscale (same aperture) Not much difference weight wise. Honestly, I think either has its merits, and you will probably be happy with whatever you buy. And TS don't even make it an easy choice by having a price difference. Tough choice, really.

AfaIk, @tomato has a Moravian with 5.4 um pixels on a Kaf8300 sensor, and an ASI178 with 2.4 um pixels on a small Sony Exmor sensor. Both on an Esprit150. What interests me is if such a dual rig with pixelscale difference of a factor of 2, can resolve much more detail than the kaf alone. My guess is that on most nights it won't make much difference. But on those very rare winter and spring nights, when seeing is at its best, and galaxies are in full bloom, those tiny pixels will make a difference.

I would go for this target, myself. But unfortunately we have "sunny side up" until end of August here in Scandinavia.

Why would you? We don't have any scientific responsibility (whatever that is), so can very much do whatever we like. It's the more mechanical part of AP. Processing is the artistic part.

That's a lovely diving whale. Very nice processing too.

My processing, very likely. It's getting late, so I'll have to continue this with fresh eyes tomorrow.

Definitely not. But when I process the lum, and combine it with the colour, I lose the very faintest arms in the galaxy. The data is in the colour image, but not in the L. Even when I superstretch the L, I can't separate the faint arms from the noise floor. But it's very evident in the blue channel of the colour image. You can just barely see it in the RGB image I posted here. I will try with the synthetic luminance.

Here's the RGB image, processed in PixInsight: Channelcombination Dynamic Crop, removing the stacking edges DBE Background neutralization Photometric colour calibration Arcsinh stretch (which is supposed to preserve colour balance) No additional colour saturation was used, and since PI is quite rigorous in its mathematics, I think that this is the closest you can come to natural colours á la PixInsight. For me, this is the starting point of my image processing. I will push the colours, and process the luminance data to keep as much colour in the galaxy as possible, while at the same time lifting the faint arms and suppressing the core. Btw, if natural colours are the aim, then how does narrowband Ha fit in? Doesn't this destroy the (natural) colour balance?

Thanks for the data Rodd. This will give me something to do now that I can't collect photons myself for a while. I'll report back when I have results.