wimvb

How are the spikes in single exposures? Long or short? If short, this means the spider may be twisted, or poor collimation. If long, the spikes are rejected /averaged out during stacking. Probably field rotation.

And don’t forget to just look at the darks. At what level are the mean and median? What about the mean and median of your lights?

Use phd log viewer to do a frequency analysis. Eg, a 120 s period would indicate the timing pulley on the RA motor. A 10 s period indicates a loose RA belt, etc. The log viewer can help. There’s a link to it on the phd web site.

good news regarding the colour. There is definitely colour in your image. I combined the R, G, and B masters in PixInsight and cropped to the central area to avoid any frame combination artefacts. Then I applied Dynamic Background Extraction and Photometric Color Calibration. Finally I stretched the image with Arcsinh stretch and followed up with a curves stretch. This is the result. In my opinion, to succeed with a mosaic, you need absolute control over gradients. This means both during the calibration process and later on gradient removal during post processing. You can't take any shortcuts, because they will show up sooner or later.

I hope you've turned off automatic updates in MS windows. Good luck.

Just make sure that the flattener to sensor distance is 55 mm, or you will see elongated stars in the corners of your subs. Good luck and have fun

Satellite trails are averaged out during stacking. Just set the parameters in your stacking software to allow more aggressive pixel rejection.

You CAN bin MONO cmos sensors which will give you a slightly increased snr, but not to the same extent as ccd. That's because the binning is done in the camera software or in the driver and not during sensor read out. Colour sensors have the colour filter array that prevents 2x2 binning. When you deBayer during stacking, you can use super pixel mode, which takes a group of 2x2 RGGB pixels to make one RGB pixel without any interpolation. That won't give you the same advantage as camera or driver binning, but it's definitely something to experiment with, though.

Don’t labels on shower caps usually say ”hand wash only”? which also applies to mirrors, of course.

🙊

Well, unless it rains without clouds in your neck of the woods, I’d put my money on CO.

Some more tweaking, cleaning up residual gradients, etc.

The main attraction in this cluster (Abell 426) is the double galaxy ngc 1275. It shows a tidal interaction between two galaxies, and eruption of Ha jets kept in place by strong magnetic fields. Old but fierce. In my image of this area, I just about managed to make this visible, but it shows better in this astrobin image(definitely not mine) https://www.astrobin.com/4063x8/B/?nc=all

It's at the back of the scope. Black, nothing fancy.

I have a cooled cmos, which needs flats, darks and flat darks. With cmos, you can't use scaled darks, and therefore you don't need bias frames. This differs from traditional ccd.

Integrate, crop, linear fit of the three masters, combine to rgb. Then dbe, bg neutralisation, photometric cc, arcsinh stretch. Chromatic noise reduction with MMT before or after stretch. Colour boost and lrgb combination. If I don’t have L, I may create it from RGB. I process rgb for colour impact, and L for depth & detail. I keep colour processing separated from luminance processing.

Since the galaxy is starless, I suspect you blended two images? This can also be the reason why you have those two dark patches.

Excellent image and very well processed. I also like how the nebula is/seems lit up. Subtle yet with strong impact.

If you upload the masters (or pm me) I can have a look at them and maybe come up with a remedy. Mind you, I don’t use APP or PS.

One thing at a time, let me finish that warp drive first. 😉

I did recently https://www.astrobin.com/cl4u0a/?nc=user I’m working on a version with a little more detail in ngc 1275, atm. I have the same colours as you.

That’s what bothered me too. The detail is fine, but at 4+ hours, I would expect more colour. What does the rgb image look like? You also have dark areas in the lower right and upper left around the galaxy. This is usually a result of inadequate gradient removal. Very common if you use ABE in Pixinsight, but I have no idea if APP caused it in your image.

Imagine how frantically that cat is jumping.

Sshh, don't let Musk or NASA hear you. 😉

The accuracy of CO varies: