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This is your lightmaster_30s image after PixInsight Process: RGB: Crop to remove stacking artefacts DBE Colour calibration (background neutralization and PCC) Extraction of Luminance to be processed separately noise reduction (chrominance only) Masked stretch Arcsinh stretch Histogram adjustments Blurring LRGB combination Adjustment of star profiles L: Noise reduction DBE to correct a persistent gradient Histogram and Curves Transformation HDR compression (slightly) Curves adjustment LRGB combination The data is a bit noisy, but if this is just 47 x 30 seconds, that's understandable. My advice: try to collect as much data as you can, at least 3 - 4 hours if feasible. This will improve the signal to noise ratio and make processing easier.

Sounds great. Will this item be part of the setup?

I downloaded two files: light_master.xisf and lightmaster 30s.xisf. The latter is probably underexposed. After DBE and colour calibration, the brightest stars have a normalised pixelvalue of 0.78 (approx.). I think you can safely double the exposure time. Underexposed stars are good if you want to keep colour down to their core, as you would when photographing clusters. But if you want fainter detail in a nebula or galaxy, it may be better to overexpose the brightest stars and get more signal. The alternative is to gather many more subs to get the noise down. At Bortle 5 you should definitely try to shoot without the LP filter. It will depend very much on what kind of light pollution you have and at which part of the sky relative to the pollution source you are aiming.

Btw, the links don't work for me. I can't access the files.

Both to some degree. All lp filters will cause a loss on colour. But IDAS are imo best in keeping colour. If you need a lp filter, by all means, keep this one. As you say, a change in colour will be corrected in post processing. And as for best exposure time, just make sure that the exposure histogram on your Canon is a little removed from the left efge of the display. Longer exposures are not needed, you gain more by increasing the number of exposures than their duration.

DBE Background neutralization Mmt noise reduction on chrominance SCNR green Colour saturation Contrast adjustments (curves) Are the files still linear? It's easier to work on them if they are. Will look at them tomorrow.

Tracking issues and atmospheric disturbances become more obvious with longer exposure times. The stars in both your images show that they were not overexposed, you've got good star colour. The 300 s image also starts to show Ha regions in the galaxy. Even though the IDAS LP filter is a good one, it will affect the colour in your image. Furthermore, DSLRs suffer from chromatic noise (colour mottle). All this has to be remedied in post processing. And I think that it is quite straightforward to do this. This is after some adjustments to your 60 s image. Working on the original xisf file would yield better results of course.

Impressive. I'll be looking forward to the progress.

So you won't be building this in wood then, as the drawings suggest. Carbon fiber? What will the fl be?

Thanks. So far so good. I'm still not allowed to bend my knee at all, it's in a brace. Healing will take a while, but it'll be allright in the end. As I haven't been able to work for more than a month (I'm a teacher, so lots of moving between classes), I was able to put together a weather station and a sky quality meter for use with the obsy.

Weather has indeed been very poor so far. Imo, you over stretched this latest image. Did you use LRGB combination? I usually stretch the RGB data with Arcsinh Stretch, with the black clipping set to 0. This will give you a lot of colour without clipping any data. I then use either Curves Transformation or Histogram Transformation to adjust the background. That's basically all that is needed for colour. I think that if you combine the RGB image with the L image that you posted earlier, you will have very nice LRGB image.

Part 6, a screatching halt With the roof in place, it was time to start with inside work. First off, the piers needed finishing. I made pier adapters out of aluminium. It turned out that the AZ-EQ6 and EQ6-R mounts can have the same adapter design. Here's my solution. This is my AZ-EQ6 in place on the west pier, and the east pier ready to accept @Firas EQ6-R. My gear will be controlled from a Rock64, which is the same size as a Raspberry Pi, and sits on top of the scope. But Firas has a Windows PC that needs to be mounted next to the pier. Here's a mock up of my solution. Next step: getting electricity installed. Here I hit a snag. Sunday afternoon on November 10, I went out to the obsy to do some electricity work. That morning we had some light snow which had all but disappeared, leaving the ground wet. Just outside the obsy I slipped and hit my knee on a large rock. I thought I had dislocated my knee cap, but an x-ray the next day showed that I had actually broken my knee cap. I had surgery on November 25, and am now on crutches. Work on the obsy has come to a screatching halt. Fortunately for me, the weather has also been very poor this autumn/winter, so I haven't lost any imaging opportunities. Hopefully I will be mobile enough for galaxy season. The obsy is operational (kind of), and I only have to install the scope and camera. Finishing the obsy is planned for summer recess. "That's all, folks!" (For now at least)

Part 5, framed Once the floor was finished, it was time to erect the walls. First I thought of building these indoors and then lift them into place. But since I did most of the work alone, this was impractical. Everything was constructed on site. August had its showers, and as soon as the frames were up, I used a tarp to cover the build. I didn't take any pictures of the roof design, but it's very similar to Göran's second obsy. In stead of ball bearings, I used rubber wheels. https://stargazerslounge.com/topic/337156-just-finished-my-second-obsy/ Fast forward from mid August to mid October, the roof is in place. Here's a view from the very North-East corner and the highest point of our property

Part 4, construction begins After a lot of digging, it was time to do something constructive, pouring the plinths. This was done in June. This image is from just before pouring. The tubes were covered to protect them from the occasional rain shower. One thing I hadn't fully figured out yet was the material to use for the pier. I wanted ventilation tubing filled with concrete, but it turned out that for some reason dimensions larger than 160 mm are only sold to professional builders. Fortunately, Göran had just built his second obsy and had almost 4 m of plastic tubing left over, which I could get for free if I collected it. This was just enough material for two piers. By the end of July, the plinths and piers were poured. Finally, the excavation site was filled in. Here's the floor frame under construction. The length of the long side is 3.9 m, and the short side is 2.2 m Once the frame was in place, laying the floor was easy. The floor is insulated with 10 cm styrofoam blocks. The floor boards are 38 mm thick, leftover from when the house was built. Btw, the holes around the piers were filled in later with smaller pieces of insulation. Next: up, up.

Part 3, the Dig Sweden is mostly one big rock with smaller rocks on top. My property is no different. The area is old moraine on which there used to be a forest. This means that the ground is made up of organic material (roots), and sand. Mixed with that are stones, anything from pebbles to boulders. And since this material was polished during the ice age, it is embedded in clay. Groundwork for the obsy started in April, with hand tools. After a few hours, the first serious obstacle saw the light of day. This was the topic of a previous thread: I bought tools to remove this stone, but in the end I decided to keep it and use it as the foundation for the west pier. The tools came to good use on other rocks. Here are a few more pictures from the dig. The beginning of a pile of rocks (this would grow) This is about the size of the dig and observatory, with a view towards the south. The hole for the east pier isn't dug yet. This picture shows the approximate size and level of the floor beams. @jjosefsen: that should answer one of your questions: the floor will be a raised wooden floor. I removed more material and dug the hole for the east pier. No images though. Next step: filling this excavation site again.

It's a roll off shed. I bought a tool shed kit and assembled it without the flooring on a frame. I had to move it last spring when we reenforced the slope behind it.

Sketchup. All your other questions will be revealed in due course. 😉

Part 2: The design of a permanent roll off roof observatory. A friend of mine, @Firas, lives in central Stockholm, and despite bad light pollution, he manages to create very good images. When he visited me at my new location, he was blown away by the sky quality, which allowed him to capture better data in just a few hours than he would be able to in Stockholm. So I suggested that he move his gear over to me, and house it in the obsy I was planning. This meant that the obsy would need room for two piers, not just one. I use Ekos/Kstars for equipment control, and one of its features is that it allows for robotic operation of an imaging rig. I decided that the new obsy would be controlled from the house and not from an adjacent warm room. This way I could keep the area and cost down. But now I needed a roll off roof design, with a large roof. Since my property is on a south slope, the piers would need to be located next to each other East and West, and this meant a wide roof, rather than a long one. The slope also makes a long roof difficult, because the south side of the observatory will be high. Other constraints are the weather. In this part of Sweden, the snow load can vary a lot, and the obsy roof needs to be strong enough to cary wet snow. I've also noticed that the ridge where my house is located causes strong local winds and the obsy will need to blend in with the environment and be as low as possible. Design 1: The obsy is about 3.6 m East-West and 2 m North-South. The sloping ground means that the roof will be very close to ground level when opened. This design has a lot of difficulties associated with it. After some discussions with @gorann, I decided to build one similar to his. The obsy would have a roof that rolls off to the south, on sloping rails. This is what I call the Hole design, because the area where Göran lives is called Hole (pronounced Hoo-le) and his obsy is named "Hole observatory". But a 3.6 m roof like this will become too heavy if it is to withstand a snow load. Plus, if only one imaging rig is used, the other rig is unnecessarily exposed to the elements. The roof needed to be split. This is a rough sketch of the design I settled on. Next: watch your back!

Part 1: About one and a half year ago we moved from the Stockholm suburbs to just outside the small village of Lindholmen in Vallentuna municipality. The night skies are much darker here (estimated magnitude 20.5 vs 17.5 in the suburbs), and I decided to build an observatory. Just to get me through the winter, I bought a tool shed kit that I set up to house the SW AZ-EQ6 with 150PDS, with the intention to build a more permanent obsy at a later date. This worked well for the 150PDS, but when I got the MN190, it got a bit tight. After the first winter at our new location, we also found out that we needed to reenforce the slope around our house. This meant I would either need to move the entire shed, or decomission it. Time to plan for something more permanent. My property is large enough, and is situated on a south slope overlooking a field. I spent early spring to plan for a good location and a proper design.

Very nice already. Hope you find time soon to catch more data and enhance the jets from m82.

Or a slight crop of the top and bottom. Just above the star halo in the lower right corner, eg. The image is very soft, so you must have had high cloud while gathering the data. But it's certainly worthwhile to revisit this area when conditions are better. Happy New Year, hopefully with more clear skies than this one.

Very nice result and well processed, despite the unfavourable conditions. At least now you know how to do it, once you get really clear skies.

Great mosaic, Göran. Gott nytt år tiil dig och Sjannie.

Lovely image with clear colours. Well processed.

In my personal experience, moderately oversampled images have been easier to process than undersampled images. While there is a general rule relating pixel size to sampling "resolution" ("rate" seems inappropriate here) and star fwhm, that only takes into account the optical and mechanical part of data capture. Imo, one needs to optimize the entire process from data capture to final image. For me, the method of choice to sharpen images is deconvolution, and that works best together with (again, modest) oversampling. But as @vlaiv notes, oversampling will deteriorate snr, so there must always be a trade off between the parameters in a given configuration. Furthermore, a configuration not only includes hardware and processing workflow, but also location (atmospheric conditions, light pollution) as well as intended targets. Nebulae generally don't need the same sampling resolution as galaxies and star clusters. All this has to be considered when configuring an imaging setup.