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Shibby

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Everything posted by Shibby

  1. Pretty much, yep. (There's read noise too). Your choices are: Light Pollution filters, which are becoming less effective with new LED streetlights Shooting with narrow-band filters. More sub-exposures. This follows the law of diminishing returns. Software noise reduction, although you'll always lose at least some detail. Generally, we'll apply it only to the fainter areas, where the noise has more effect.
  2. You're learning from the best there. I've followed his website for some time now - the precision he manages is incredible.
  3. Thanks! I'll have a go at that. More importantly, perhaps, I've noticed on my desktop monitor that the background is a bit of a mess, so I should sort that out with the fore-mentioned "long, careful" version.
  4. Here's an attempt at a target that needs no description - the Crab Nebula, in bi-colour. For this one I decided to go for 300s subs, although I can't specifically remember why... I did a "rough and ready" process, followed by a long, careful one. In the end, I preferred the first version so here it is! I didn't bother with a star layer as they're not particularly bright. Any feedback/ suggestions appreciated, thanks. Hα: 31x300s (R) Oiii: 17x300s (G+B) Atik 460ex SW MN190 Orion 50mm guidescope + QHY5L-ii Stacking: DeepSkyStacker Processing: Photoshop
  5. As you say, it's unwanted signal. So it's not really treated as noise - procedures like stacking/calibration and noise reduction don't have any affect on it. Think about a pixel in your image - some of the signal in that pixel comes from light pollution, some from the target. By "removing" the light pollution aspect with whichever tool you use to do so, you're left with the signal from the target. So in theory, you're not removing that signal from the DSO as the sky brightness adds to the signal, rather than replaces it. The real problem is the magnitude limiting - when part of your target is so faint that the difference between sky and target is so small it falls within the read noise of your camera, there's not much you can do to recover it. With a really dark sky, you can just expose for longer. I must admit, I don't know much about the theory of all this, so I'm sure someone wiser will be along soon...
  6. Here's my image of the Cat's Eye Nebula in Bi-Colour Hα/Oiii The central nebula, very bright, was formed ~1000 years ago. The other nebulosity, much fainter was apparently ejected from the star previously every 1,500 years or so. The different age material then interacts to form the various shock waves & knots you can see. To capture that bright, inner nebula, I took a series of just 10s exposures. The rest of the nebula required 10 minute exposures, so that gives an idea of the difference in brightness! I struggled a bit with this one, as you can probably tell. Partly down to my lack of processing skills, partly down to the fact I was constantly chasing this into my light-polluted horizon for a few nights. Hα: 17x600s (R) Oiii: 17x600s (G+B) Atik 460ex SW MN190 Orion 50mm guidescope + QHY5L-ii Stacking: DeepSkyStacker Processing: Photoshop
  7. Yeah it's a tough call, especially difficult bearing in mind that our images look different on every monitor! Well, it's working fine, just not in Artemis still. My filters aren't parfocal anyway, so I'm happy to manually change them for now...
  8. A very impressive swath of sky you've captured! Perhaps there's a way to combine Ha as red with some creative processing? Some of the stars look right, perhaps due to the longer exposures of Ha. On my monitor, I can clearly see the 6 panels, so I think it'd be worthwhile having another go at combining/tweaking the mosaic.
  9. Great work Carole, it's looking great. Good effort, ploughing on from 2am! There's a bit of noise showing in the background so the image might benefit from dropping that back a bit.
  10. Thanks for letting me know. This screen does need some work! ? I started one but haven't got all the views working correctly yet - hopefully "soon"!
  11. It seems the film was very divisive! Personally, I thought it was great and had a very good, authentic feel to it. To me, the characters were far more real than those portrayed in Apollo 13. In fact, Neil Armstrong's sons have defended the portrayal of their father so it can't be that far off can it? I'm not sure why it's such a problem that the actual flag planting was missed out; there wasn't that much screen time devoted to the lunar surface anyway. The film was about Neil Armstrong, not specifically about the lunar landing. Besides, there was plenty of pro-American content such as JFK's speech.
  12. Hi all, I know it's been a long time coming but just wanted to let you know that I've finally released an update for Astro Panel. It's not perfect yet by any means, so I do plan to release some more updates in the near future! An important improvement is the great reliability of the new server provided by @ecuador Release notes: New darkness screen. Finally added a (basic) widget! Improved reliability of clear sky alerts. Now defaults to new 7Timer server; old server for backup. Fixed a bug in lunar altitude and another couple of small bugs. It may be a couple of hours before the update is visible to all users. Please do let me know if you encounter any issues with the update. Thanks
  13. Precise measurements can be very difficult. What magnitude of star were you imaging, and how deep is the dip you're looking for? For a mag 12 star, I settled on 120s exposures, so 5s seems a bit short if you're hoping for a good star profile? Also, how many reference stars are you using? The more the better, but it's best if they have similar colour profiles to your target.
  14. Great job capturing something so faint with heavy light pollution. It's Bortle 5 where I am but heading for 6 with new developments.
  15. Super effort, super image. You've done well do present a large dynamic range, deal with all those stars and everything else going on!
  16. Looking great, will be interesting to see how/if you combine it.
  17. Not having much other data to play with, I thought I'd reprocess this. I've only done the Hα as this is clearly the best data - perhaps I'll get some improved Oiii in the future. I've uploaded a larger image and also flipped it the right way around (looks weird after staring at it in reverse for so long!) Maybe it's not that different now I compare, but the stars are improved I think? Here's the direct link to the large size image: The NGC7000 Wall in Hα
  18. Very nice - excellent, strong colour!
  19. Nice work! Good to see you managed this with budget equipment. I've been trying my hand a photometry recently, although I haven't posted anything on SGL. (Photometry normally goes in this forum though: https://stargazerslounge.com/forum/52-observing-and-imaging-double-and-variable-stars/ ) I've been using this transit finder: https://astro.swarthmore.edu/transits.cgi
  20. I agree with the above - I suspect you have "Apply adjustments to the saved image" selected in DSS. It's a radio button in the "Save As" dialog. If you're lucky, you may find the original (unadjusted) stacks on your HDD named "Autosave.tif".
  21. Struggled most of the night with guiding issues (poor seeing?) Eventually, turned it off and was delivered perfect 10min unguided subs! ?‍♂️

  22. Well, yes, you can virtually never have enough data - 5 is very limited. 16 is a good starting point, as that enables you to stack with sigma rejection in DSS, which really brings the noise down. Other than that, careful processing can bring out more details using iterative curve adjustments. Aim not to "clip" the levels at the black end, otherwise the faint nebulosity gets lost. There are plenty of good tutorials out there, so it'd be better to read some of those than have me ramble on about it
  23. Thanks - I shall give that a go this evening to see if it helps! I feel a reformat coming... Although, I dread making things worse while it's (sort of) working!
  24. Simply amazing! The Ha has added so much extra, fine structure - it just looks stunning.
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