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blackparticle

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Everything posted by blackparticle

  1. Darks.. um.. I used my 10min set and let DSS auto-compensate. The SX camera has such a low dark current anyway that all they are there for is help with hot-pixel and bias removal.
  2. It's been ages since I got out with the scope. Circumstances dictated a house move so apart from being offline and in a state of chaos, I missed the best of the winter darkness while everything was boxed up. On the plus side, my new location out in rural Devon doesn't have the glare of Basingstoke ruining my northern skyline (But does have a pub across the road ) As a result, 15min subs now show at least a 3x - 4x score improvement in DSS and even surpassed my previous best score on the 45min sub by at least 50%. Total exposure time now is 15hrs 45mins. I've added in another 25 x 15min subs and a couple 20/25mins although I felt my polar alignment wasn't perfect after nudging the mount while trying to protect everything from a freak momentary blizzard. So I stuck at 15mins for this session as they were all looking quite sharp. I couldn't decide on which stacking method was giving the best results so did an entropy, adaptive average and median kappa-sigma and stacked the 3 results together. After seeing how the image has progressed and is now hinting at previously hidden detail I reckon I'll stick with this for at least another session.
  3. As that's only 90mins-ish!! How about just go for a 2x2 mosaic with the EF200?
  4. I tried something similar with M33. I think I did approx 450 at 1min (unguided) and then compared this to a similar 7hr stack of 5, 10 + 15 minute subs after I had my guiding working. The results were no contest. The stack of longer subs contained much more faint detail that the shorter subs had failed to capture. The other main bonus was stacking time was reduced by half a day.
  5. Now why didn't I think of that !! You've just saved me loads of time phaffing about going in and out of the caravan.
  6. I tried this out tonight and it put me back to within about 200 pixels of the bookmarked location. I had to run off a test sub to be sure and then did the last adjustment by guesswork on the handset. It was far less painful than staring at a blank frame/focus preview wondering where the target was.
  7. Not necessarily true. 3D space/time as defined by our science didn't exist. 0D non-space/time is perfectly possible.. In fact, an infinite amount of time could have passed before the big-bang brought this universe into creation.
  8. A tricky one this. If quantum mechanics is correct and the physical universe only exists when under the direct observation of an intelligent mind, then the 'creation' of the universe itself from nothingness could imply that it was formed from the imagination of an intelligence that existed within 0-dimensional voidic non-space. Time itself can exist without dimensional space so the big-bang could have happened when that intelligence finally got bored and gave up existing in 0-D and all those thoughts and possibilities then came into existence.
  9. Hot pixels are sensor defects. Some show up after just a couple of minutes.. others only appear after really long exposures. They are to do with leakage currents from the individual well. Cooling helps but will never get rid of them completely. It's part of the reason dark frames are a must when imaging. As for over-exposure on a target. There are not that many objects bright enough to cause this. M31 / M42 are definitely exceptions and require a combination of both short and long subs to capture the full dynamic range.
  10. An increase of 0.1 FWHM may only represent an improvement of 2 or 3% when averaged out but I find that doing it this way, by the numbers, assures me that the focus is the best I can achieve and removes any niggling doubt that it isn't bob on. It's also quite easy to come back to later in the session for a re-check without touching the scope which I've found can disrupt PHD's guiding, especially if it has settled down to a nice flat line.
  11. Nebulositys fine-focus routine is on a shot-by-shot basis. You set the exposure length, pick a star and off it goes. What it gives you is a graph and although the seeing varies the results, you can easily tell when you've hit best possible focus as the FWHM will drop down to a figure that is obviously better than the rest. When I hit this peak in the graph I know I've got the best focus I can achieve. The fractional adjustments to the focuser are so minute that you wouldn't really be able to tell on a Bahtinov mask (well I can't anyway). The amount of adjustment required is sometimes as light as stroking the end of your nose with your fingertip.
  12. NGC 2146 is a a spiral galaxy in Camelopardalis that has recently undergone a galaxy collision or disruption. It's not very big and certainly not very bright at Mag 10.5 It was also one of the imaging targets this month at the Norman Lockyer Observatory so I gave it a go. And possibly a first for SGL apart from someones quick go with the 2m Faulkes Telescope which in itself should have given me a clue to just how hard this thing is to image. I could have waited until this was completed before posting but as a relative newbie to astro-photography I do like to see works in progress and how they unfold as more data is added. It gives me some idea of how much time has to be put in to achieve a result. Current imaging time is 6hrs in subs ranging from 15 - 30 minutes with a Mak150 (reduced to approx 0.6x) / SXVF-M8C / Neq6. Lots of noise still but it's there and starting to take shape. Alan.
  13. While the shipped SX software may be naff, Nebulosity (which you already have) is an excellent choice for capturing. Choosing between Atik and SX when comparing identical chip models... I don't know if there is that much in it. The electronics inside are going to be pretty much of a muchness and I'm sure both companies use choice components. I'd say the regulated (C-core?) PSU that SX use is way better than a generic 12V switched-mode PSU. Like with audio, anything that uses an AD convertor gets a performance increase when the PSU performance is better. Having said that, once you start stacking images this may not have the same relevance as it does with audio. I do prefer the form factor of SX cameras as they offer the possibility of using an SCT with Hyperstar although this is a minor consideration. As for the popularity of something like the 4000. I think it comes down to one thing.. The price. I'd love one myself but suspect without a similarly priced scope to put it on, it would be overkill. I've got a habit of splurging on gadgets (as I'm sure a lot of us here do) and have really had to reign myself in since getting into astro-photography lest I end up with a bank balance redder than a drunkards nose. God help me if I ever win big on the lottery.. It would be gone in a week! heh Alan
  14. I've not used the User Defined Database in the Synscan controller yet but I just want to run something through here to confirm it works like I think it will. Sometimes my alignment is not as accurate as it should be so I want to bookmark an exact location for the session with the handset. So, I'll find my target, frame it up exactly without a filter in so I can see it.. Store it to the DB.. Then switch to the Ha filter, slew to the nearest bright star so I can focus it up.. And then recall the location from the DB. Will that put me back exactly where it was? I realise the DB entry would only be good for that session but that's fine. It just needs to be accurate in returning to the marked location. Ta, Alan.
  15. Galaxy shaped pastries.. Now there is an idea !! It might even top the Jaffa Cake as the astronomers snack of choice.
  16. I've seen people say that if you can guide through one worm cycle without a hitch then you shouldn't have much of a problem guiding through many. Obviously in reality there is more to it than this.. Clouds, balance, cable movement etc. But under optimal conditions, what length subs have people gone for and nailed successfully? I tend to start at 5 or 10 mins and work my way upwards with sub lengths and back off again when the sub starts to show signs of smear. The reason I ask is that I experienced serene levels of calmness the other night. PHD was as flat as you like with the OSC-Index and RMS both sitting at 0.03 and I got up to 45mins without a hitch (With a Mak150 reduced to approx 1m focal length with a 3.125um pixel CCD on a NEQ6). I would have pushed for longer but it was approaching the end of the night and I wanted to keep the sub within the astronomical darkness window. So did I get lucky? Divine intervention? or is this something that should be consistently repeatable given similar conditions? Looking at the sub itself leads me to think that longer IS better. Are we just playing it safe stacking many shorter subs as opposed to going for a theoretical maximum? So really, just curious to know what others have max'd out on and what mount/scope/camera they were using. Alan.
  17. I've given up with the Bahtinov masks in favour of the "fine-focus" feature in Nebulosity (which is what I use to capture with). While I found the masks get you there or thereabouts, the live capture FWHM reading gets me the best focus possible as it doesn't take more than the lightest touch on the focuser to adjust the values by something as small as 0.1 FWHM. These subtle differences don't appear to be resolved to that level of precision with a mask.
  18. I think this is the first image I've seen that has both astounded and depressed me at the same time. I spent a frustrating night trying to add the longer subs to mine, lugging the gear out to the bottom of the graveyard to try and get a southern view only to have the NEQ6 refuse to behave itself. I'm starting to think that the NEQ6 doesn't like being under-loaded with just a 66 and finder/guider. On the plus side, seeing this means I can give up on it now and stick with chasing smaller objects with the Mak which seems to force the mount to behave itself so well. p.s. The added Ha version is even more stunning.
  19. Great image. After the results I've had so far galaxy hunting with the 6" Mak, seeing this has put a much larger aperture scope on my wants list for next year for when I run out of "easy" M-targets. My one attempt at something this difficult (NGC 2146) has proved to me that going for galaxies at Mag10 really does require something pretty big. What mount did you have the scope sitting on btw.. Was it the AP1200 as listed on your site? I wonder how a NEQ6 would cope with something like the Edge 11?
  20. I had a shot at this with a 66. It's nice to see how all those filaments should really look. Also, do you not get diffraction spikes with your Newt when shooting Ha or are none of the stars in there bright enough to produce them?
  21. I spent the first part of tonight battling against NGC 2146 which prepared me for another session on this. Weirdly, as soon as the moon set, the wind died, the clouds vanished and my PHD graph went into cardiac arrest and totally flat-lined. I managed to double my sub count.. Now up to 31.. consisting of - 7 x 5 mins 6 x 10 mins 7 x 15 mins 7 x 20 mins 2 x 25 mins 2 x 30 mins 1 x 45 mins << Yeah.. I couldn't quite believe it either !! Running total is now 8hrs 5mins and I'm still classing this as a work in progress. As I did 5 nights the first time around I'm quite prepared to go the whole hog on this. I tried the adaptive method of stacking but I think I prefer the entropy method. The adaptive was smoother but entropy brings out more of the dust clouds. To get it working properly I'm going to require a lot more of those longer subs. I'm more than happy with the improvement and progress so far though.
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