wimvb

As in here: Close up of a lacerta newton reflector. Very clever design, as it minimizes diffraction.

Looks good.Now you just need clear skies to test it.

I can relate to that. I'm still looking for a solution to my cable spaghetti.

NEAT!

Ah, that makes sense. I never bothered to flock my 150PDS, but I am very interested in your RCA solution. So keep us posted.

So, what's the plan? Or is the 130PDS delivered as an IKEA set nowadays?

No, you don't use the ds function. But otoh, the slow setting of the controller is good enough, and as @lnlarxg wrote, the whole point is to be hands off, so you don't introduce vibrations. With the motor turned off, you may be able to loosen the connecting piece between the focuser and the motor to allow manual focusing. I've never had use for this. If you use the handcontroller that comes with the autofocuser, just make sure you have an extra 9 V battery at hand. You wouldn't want to lose power in the middle of a cold viewing/imaging session. As for me, I replaced the hc with an arduino that emulates the moonlite protocol. This makes my focuser indi (and maybe ascom?) compatible.

The sw 150pds, but very similar, afaIk. The bracket is fixed with the 4 corner screws. You need to remove the focus lock screw.

Of course it is, but it was on top of a table, after all. ? Picture nr 3 showed it as a regular tripod in the background.

My first reaction was Pink Floyd. I wonder why? Cool collection of gear though.

These are sound selection criteria. 1. I try to avoid stars with obviously low amplitude, and always avoid stars with an amplitude larger than 1 (note that the amplitude value is a calculated one; real values are always < 1 ). But the latter usually have gaussian profile anyway. During the selection part of psf, I go for stars that just are barely visible in the linear image, with stf turned off, and those slightly dimmer. 2. I haven't found this to be a real problem, and sometimes it can be difficult to avoid those stars. But if you can create a reliable star profile without them, the better. 3. Always good practice. The optics will determine which part of the image works best. You'd want to avoid any stars with obvious eccentricity issues.

The psf process models stars with a mathematical function. It assumes that optics, atmosphere, seeing, and tracking together, produce a bell shaped star profile. For small and medium sized stars, the exact function is a little pointier than a gaussian function (traditional bell shape). But when the camera starts to saturate, (and maybe with a high level of oversampling?) the profile becomes less pointy, and resembles a gaussian function. Deconvolution tries to reverse the effect of seeing, not camera saturation. That's why moffat is generally better. Otoh, you can always try to use a tool outside it's intended scope. That's why I thought that it might be used to correct stars that become bloated. But it just can't be used on overexposed stars.

Somewhat less in a rush, I've had time to think about this. My initial thought was to use a gaussian PSF for deconvolution (because the largest, brightest stars have more of a gaussian shape). But when I thought about it I realised that bloated stars have a plateau, where deconvolution will cause a ridge to form, as in the attached image. On the left is the bloated star; on the right is the deconvolved bloated star. The intensity of the deconvolved star is 0.99 on the ridge, and 0.96 in the middle. Btw, this image isn't stretched, it shows the star in its linear state. But I did resample the image 400 %. The only way to avoid this ridge is to make sure that the star is less bloated. This can be done by slightly blurring it. With AtrousWavelets or MLT, remove the first two layers (using a star mask of course) This doesn't make the star smaller. But it will give it a slightly rounder top, which will tolerate deconvolution a little better. Since all this is done in the linear stage, differences will be very small. When I tried this, I had to experiment with the regularisation settings (increasing layers to 3, and increasing the noise threshold for all layers). I didn't particularly like the resulting star shape, even if it was visually a little narrower. in the end, this method for keeping stars under control is probably easier: http://www.pixinsight.com/tutorials/NGC7023-HDR/index.html#High_Contrast_Small_Scale_Structures

Just keep those draft extracts coming.

If the stars are overexposed, and have a "flat top", while still in the linear stage, deconvolution can at best, only decrease the halo somewhat. (I have an idea about a possible method, but must test it first. It involves going against "best practices" for deconvolution.) Morphology transformation may be a better tool for reducing large stars. If the number of regularisation (now, there's a word for scrabble) layers is increased, and their levels, it's possible to target only stars in deconvolution. Also it helps if the number of iterations is increased and dark ringing protection kept to a minimum. This needs to be done with a star mask that only targets those large stars. As you wrote, experimentation is required.

That's a great write up, Steve. Thanks for sharing this. Just a few minor remarks. 1. While it is possible to apply deconvolution without a luminance mask (you have to play around a lot with the Regularisation parameters and dark ringing parameter), imo, it usually pays off to use a Luminance mask with strong protection of the background. Just applying the STF as a permanent stretch, doesn't always give enough protection. 2. If you want to avoid ringing alltogether, make sure you have a preview with smaller stars over bright nebula. This is usually the first area in an image to show ringing. And if the plan is to use HDR processing later on, that will enhance any ringing artefacts from deconvolution.

I've had this kind of board untreated for 20 years in my storage/toolshed, with a second freezer that needed defrosting occasionally. It's remarkably stable. As long as water doesn't collect for longer periods, there's no risk of damage. But it does get dirty and grayish after a while. Ideally you'd cover it.

+1 for taking flats. Even if you can remove the gradients, you're still left with those dark spots. It's always best to calibrate out artefacts than it is to reduce them during post processing. Most dust bunnies originate from dust specs near the camera window. With luck you may be able to get rid of them with new flats, as @Ouroboros noted. Any remaining gradients can then be reduced with either DBE in PixInsight or Gradient Exterminator. PixInsight (on your jpeg, which I wouldn't normally do): DBE x 2 Background neutralised HDR transformation at 50% Cleaned up some of the dark rings around the smaller stars Tweaked contrast and saturation, reducing the dust bunnies (this also reduced the faint nebulosity a bit)

"It's a hard knock life."

Why not just open the roof then? That's the best and cheapest ventilation you can get. A warm day is most likely a sunny summerday anyway.

10 C difference seems excessive. Have you tried measuring behind each panel? My guess is that there won't be much of a difference there. Although you may need larger sample boards to get reliable results.

An air mattress at a building site? You like to live dangerously, don't you? Seriously though, the build is coming along nicely. Have fun & clear skies at Kelling.

Only two are of interest for astro on a Raspberry Pi: Debian if you want to follow the RPi tutorials, or Ubuntu Mate, which I find easier with Kstars. But as has been said before, if you want INDI without the hassle, StellarMate or ASIAIR should be Plug and Play.

Works fine on a Pi, but on a Rock64 it somehow wouldn't work. It used to be an issue on the Pi a long time ago. But it's solved now. So I was kind of surprised that the issue persisted on the Rock64.

Seems safer to me. It's what I do. I had trouble running the ASI 120MM guide cam and ASI174MM imaging cam together on one Rock64, so I added another one. This also gives a bit more redundancy. Should one computer fail, it's easy to start INDI on the other one, and continue the session.