wimvb

Time saving. Especially when mmt needs to calculate the wavelet layers, this can be time consuming for a large image. And as I wrote before, I’m not convinced the image needed drizzle to start with. In fact, I would like to see a non-drizzled version of this image. My guess is that the level of detail will be very much the same.

My take on your image. Also in PixInsight. Resample 50% to reduce the image size. Stars are still quite round after this, and I'm not convinced your image was undersampled to begin with. Undersampling depends very much on atmospheric conditions, and as long as stars don't appear too pixelated, you're probably good on the sampling scale. Just test with integrating this image without drizzle. Dynamic crop to get rid of stacking edges DBE approximately as per @Spongey's excellent write up. Background neutralization and Photometric Color Calibration Stretch 1 using arcsinh stretch Stretch 2 using curves SCNR green cast removal Local colour saturation and dynamic range extension using MMT with a mask to isolate the galaxy Background desaturation Saved as jpeg I didn't use any noise reduction except SCNR-green. Btw, you caught quite a few distant galaxies in this image.

You can plate solve an image at astrometry.net. For identification, I use Simbad or Aladin http://simbad.u-strasbg.fr/simbad/ https://aladin.u-strasbg.fr/aladin.gml

I'm currently working on the little pinwheel galaxy, ngc3184. In the same fov I have two galaxy clusters, one (aco 971) at 1.2 billion ly, the other at 3.6 billion ly. And then of course, there may be a few quasars in the image that are even further away, as @Craney already wrote about. Ngc 3184 itself is at 40 million ly.

There’s your problem. What you describe are symptoms of underexposure. Either your sub exposures are too short or you have too few. More data is the best solution. Withe the moon about, you need even more data in order to reduce the noise caused by moon light.

Mono: bin at capture Osc: bin in preprocessing (super pixel debayering) From a light polluted site, I would probably choose mono. It's easier to do both rgb and narrowband imaging. From a dark site, osc works well. You cand do nb imaging with a dual band nb filter.

A 4-6 um pixel camera binned 2x2 or an osc camera in super pixel mode, should do.

As promised:

Actually, no. Many zwo cameras have rolling shutters. Just not mechanical. Still, there can be problems with short exposure times. But there’s only one way to find out: examine the images.

Maybe those settings are (also) used in the other algorithms that are implemented. The linear algorithm was added to ekos about a year or so ago. This may be a legacy setting.

The double outward move (400 steps initially) and large inward move before the sequence starts is there to clear any backlash. Honestly, I've so far not bothered about this. Next clear night I can try to save a focus sequence and post it here. Yesterday, before I started imaging, I had to refocus my oag guide cam. When I put a bahtinov mask on the scope to do this, focus of the main camera was still spot on. The routine works ok for me.

Here are my settings (most of the relevant information is under the "Mechanics" tab). As I wrote earlier, the initial step size is 40 for my Pegasus focuser (50 was too coarse), and I just changed the "Out Step Multiple" from 5 to 4. When the routine starts, the focuser will first move 2x4x40 = 320 steps out, then 160 (4x40) steps back in, in order to clear backlash. It will then focus inward 40 clicks until it has detected the V-curve. After that it will move out again (followed by a move inwards to clear backlash again). It will then focus inwards with half the initial step size, to find the best focus position. This position should not deviate more than Tolerance from the prevsiously found minimum HFR value. If you leave the Tolerance at the default (3%?) value, the routine will often fail to get focus, because of variations in hfr due to seeing conditions.

When you use the ekos focus routine, you need to be near focus for it to work. I get there by setting the focus routine to loop exposures and slowly, "manually" change focus in Ekos. It also has more trouble with reflectors due to the donut profile while out of focus. I use the linear focus routine where it measures the v-curve and does two passes. The step size is 40 ticks with focusing 5 steps out (200 ticks). I use full field focusing. This works good enough for me. As the routine starts at the last best focus settings, this almost always finds the best focus. I use the pegasus astro focuscube on my mn190 with stock focuser. Hope this helps.

My contribution. Processed in PixInsight

Alloy?

I use an old asi120mm with a raspberry pi. Not that difficult to set up. An acrylic dome from amazon and short bits of sewage pipes and ends for the enclosure. https://github.com/thomasjacquin/allsky

Jasem is THE man behind ekos/kstars. The only other developer who comes to mind would be Radek Kaczorek, RadekK on sgl. He's the developer of astroberry.

What are your expectations? Even if you have done everything "by the book", and expect those crip details, it can be atmospheric conditions that limit the level of detail you can achieve. So if your expectations exceed what your skies allow, there really isn't anything you can do during the capture phase to improve.

If you set the camera to gain=120, you have a steep drop off in read noise, and a boost in dynamic range. This allows you to use shorter exposure times. But (!), always be sure to choose the exposure time so that you stay above the read noise floor. Especially in a dark sky zone, there may be very little sky glow to keep the noise above read level, and you may have to use longer exposure times. Just experiment. I choose my exposure time such that I don't saturate too many stars. This allows me to keep nice star colours (such as in the above image).

Thanks Adrian. I think it's the camera's dynamic range that helps to maintain core detail. The newest generations of CMOS have such low read noise, that you can get away with a large range of exposure times. When I started using the camera, I settled on 90 s exposures for L and 150 s for RGB. But lately, I have used 150 s for all filters, and could even increase RGB to 300 s. Even with my 7 nm Ha filter, I don't have to increase the camera gain, and can still keep my exposures short. I have imaged the monkey head nebula at a standard gain of 120 and exposure time of "only" 300 s with good result. The camera allows for a lot of under- and overexposure.

Thanks Martin. I use the camera in its "unlocked" native bin2 mode. I don't think there is anything to gain with the camera being unbinned. Atm the pixel scale is 0.96"/pixel. At bin1 that would be 0.48"/p. I don't think my atmospheric conditions are good enough to get sharper images at bin1, and my guide error is typically around 0.6 - 0.65" when conditions are good. At the same time, at bin1, the camera has only 12 bit output, which means a lower dynamic range, and four times larger image files. That alone would bring my processing computer to its knees. For this image alone, that would mean 120 x 92 MB fits files, more than 10 GB of data to process. However, I wouldn't mind if you prove me wrong. That would give me an excuse to go shopping for a new computer. 😄

Thanks! Martin( @Budgie1), by all means, go for it. M3 and M13 are positioned favourably atm.

2,5 hours of RGB data while the moon was at its brightest. Gear: SW MN190 with ZWO ASI294MM, Optolong RGB filters Exposure: 20 x 2,5 minutes per channel Processed in PixInsight.

http://www.aicccd.com/archive/aic2005/The_unexplored_nebula_project-smandel.pdf

Quite a few more according to the HyperLeda catalogue