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NGC 666

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  1. You actually notified me of a really interesting event - I'm grateful! On Stellarium, it's visible all night long near Orion and peaks at Mag.10.3 or so (quite visible by cameras through most equipment). When it is closest, it moves so fast as to be like a high orbit satellite - races passed the Plough at a visible speed in real time. It's a bit like that eclipse of Regulus last year, but this time visible everywhere and lasting longer. Images may just be a dot, a blurred one at that. Nevertheless quite a rare dot.
  2. It looks like, especially if this is a single sub, that the scope was nudged - maybe by a bit of wind or you stepping by it, which causes those spikes on top of the usual trails. They become more blurry at the edges of the image because of spherical aberration - present in virtually every reflector scope, and fixed with a coma corrector. What ISO/exposure length are you using? Because the light pollution is becoming close to saturated in that image, which would be very difficult to edit out.
  3. I've experienced this problem all too often with most DSOs, but M31 is probably the most affected. The level of light pollution is great enough to wash out all of the dim outer edged of the galaxy. Because the two are similar colours, it makes it even more difficult to extract, which it appears you tried to do, and in the process, clipped out the galaxy with too harsh use of the black point. The gradient in the photo doesn't help, either. Possible solutions are: flats, and/or GradientXTerminator, to remove the gradient, and moving away from light pollution (or getting a filter). I'm sorry to s
  4. This is all assuming you are starting imaging (having looked at your current kit, this should be new to you - correct me if I'm wrong). I recommend you focus mainly on upgrading the mount to a reliable, sturdy and low PEC one. It is quite possibly the most important thing when imaging (especially when imaging DSOs). I have an EQ5 unguided, but would love to have and definitely recommend an EQ6, or AZ-EQ6 guided mount to track the stars on simply because of their great performance (much of which I have read about, not to mention the GoTo). Both are compatible with an autoguider. There are even
  5. To me, the data is nice and solid, but the dimmest parts seem to blend with the sky/background glow because of something you did when processing (I have a feeling it's over sharpening). For example, there are areas darker than the average background glow where there isn't any nebulosity (mid right) - which shouldn't make sense: it shouldn't get any darker than where there is no nebula. My suggestion: either take it easier when sharpening, or only sharpen the centre of the nebula. Then, if you like, you could lower the background level with the levels or curve tool. If your software supports th
  6. When I try to open stacked Autosave TIFF files from the stack, they are around 250MB and sometimes don't open in Photoshop. My solution is merely to save picture to file in DSS, then import that to Photoshop. Works every time. The file is usually smaller, too - especially when cropped (in DSS) to where all photos stack. If that doesn't work, you could try cropping the TIFF file in two in DSS, then importing both into Photoshop and stitching them back together. I have never seen a 450MB TIFF file, though...
  7. Also, bias frames will help remove those faint lines going across the image.
  8. Sorry, just read exposure specs. Flats would help remove the gradient - as I'm sure you've heard/read already, but especially so with an object like M31 which is largely affected by gradients because it is large and dim at the edges.
  9. I had two attempts, one in 16-bit, and one in 32-bit. The 16-bit happened to work better. (In Photoshop:) I used levels (black point/eyedropper) to get rid of light pollution, and the grey eyedropper in levels to change the colour. I also cheated a bit by darkening certain areas of gradient with the black eyedropper tool in levels, too. The Galaxy is a weird shape I think because it is difficult to separate the data with the gradients in the image. I also added the smart sharpen filter. You didn't do too badly, considering this one is a VERY tricky photo to separate data from light pollution.
  10. I had a go at both adding saturation and changing the grey point/white balance in Photoshop, since it appeared a bit blue to me. Adding saturation, however, did bring out colour noise (the purple), so it should be used with caution. You have a nice amount of galaxy in your data, so well done there.
  11. Sorry, but I'm not sure how to download it. Google Drive or Dropbox or something?
  12. It looks like you have a reasonable amount of data to play with, because the image is not that noisy - it has a good noise-to-signal ratio. However, your black point is set too harshly, meaning you're actually removing precious data! The black point is the darkest point of the image. The white balance is a bit off, too, but that's more to do with personal taste. I like it accurate to how the object looks to the eye (if you could see colour through a scope), but it doesn't have to be that way to be a pretty image. I have never personally used GIMP - instead, Photoshop. The stars are nice and ci
  13. Assuming you have Photoshop, or software which can use levels/histogram/curves, you can use the set black point on the levels tool on the light pollution, which sets the black point of the image to be the level colour of light pollution. (NGC 6946 without black point set to light pollution) (NGC 6946 with black point set to light pollution) You have to be careful not to remove precious data of the object you're imaging, and may have to correct the white balance afterwards. Sliding the black point slider on the histogram (in levels in Photoshop) can also do a similar job, just less precise. T
  14. Apparently using Off Axis Guiding reduces the amount of light that goes to the imaging camera. Also, it's a problem finding bright enough guide stars in the main scope's small FOV, and you'll probably end up using extension tubes to focus both the camera and the autoguider simultaneously. There is less flex between the tube and the autoguider when using OAT compared with a guidescope, and you are zoomed in more with an OAG, so I'd assume it'd be more accurate at guiding - but I think the advantages don't make up for the aforesaid drawbacks. Even though I've never guided, I advise a guidescope.
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