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discardedastro last won the day on September 15 2019

discardedastro had the most liked content!

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About discardedastro

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    Star Forming

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    Oxfordshire, UK
  1. Definitely looks like a gradient to me, yes. But a really good image! Beautifully framed and tons of detail, very sharp and nice round stars. Lots of cloudy nebulosity visible. Incredible photo for a second attempt at imaging! I took the liberty of throwing the image through PixInsight's DynamicBackgroundExtraction and it spits out this nice orange gradient which looks like textbook sodium light pollution to me. Subtracted gets you this:
  2. So, here's my next challenge - cleaning out this tool. I've been going at it with a fine point needle and some running water. The tiny little pockets of grit are the ones giving me most concern - it's very hard to get in there and clean them out. I can get a dremel and start just widening all the holes out etc, but not sure it's the best plan. I can backfill all the pits with wax or epoxy. There's also a bit of 80 grit being held in the epoxy around the edges - I think some gentle sanding should get rid of that though. That or I could just pour a fresh tool and make it with thick glass tiles epoxied on top and wax between the tiles so I can effectively clean the whole thing properly between grits without spending a few days digging increasingly tiny bits of grit out of the tool surface.
  3. The most important thing to spend the money on for AP is not the telescope! It's the mount. Long focal lengths require good tracking and normally guiding, so cost ratchets up rapidly. I'd be looking to save up a bit more if you want to go for a telescope that can do DSO imaging. Or as Carole says, go for a standard DSLR camera and a Star Adventurer or similar for wide-field - wide field requires less perfect tracking (though I'd also look at the iOptron camera tracking mounts which have a nice in-built polarscope for ease of alignment). Second hand mounts are definitely a good place to start out. EQ5 and above will do well for pretty much anything up to and including a 200mm Newtonian but ideally you'd go to something a bit beefier at that. Refractors and cameras with shorter focal lengths will definitely be an easier way in at that price point, especially if you've already got a suitable camera.
  4. Now I have a way to measure, even roughly, I've been making good progress - it helps to be able to "see" what you're doing. I've got everything down to about .41-.42mm pretty evenly now, which is about where I need to be I think. So I'm going to clean everything up and start on 180 grit. My main concern at this stage of things is the tool. There's a lot of small bubbles and voids containing grit. I'm hopeful I can get it all cleaned up, but I might struggle to get it completely clean, in which case I'll either have to attack the tool vigorously with a dremel and a diamond bit, or cast a fresh tool (and I will use epoxied-on glass rather than embedding it this time, and use the wax trick in the gaps). Much rather get things into a sustainable position for fine grinding now rather than later. If I can get it completely clean I might try and do a wax covering to fill all the voids. I have a better set of vernier calipers on the way to improve my spherometer measurements along with a 0.001mm dial indicator - hooray for eBay, both used-but-good-nick digital Mitutoyos for under £30. And last but not least I've got all the bits to make a mirror mount for Focault testing, and assembled a rough-and-ready Focault tester stage with some foamcore - I just need to rebuild this in wood/plastic print and then get a little X/Y stage to mount it on.
  5. I'm still working up a process. For that image I cheated (using batchpreprocessing) to get master frames without too much faffing about, and then combined all four L masters into a single-pane mosaic, then re-aligned all the individual masters relative to the single pane mosaic, saved those files to use GradientMergeMosaic. I had another crack at processing with the R masters and used a synthetic star field to do the initial alignment, and faffed around with cropping to get all the images to an identical size to use dnaLinearFit. That produced a better result overall. Definitely feels like portions of this should be automatable - particularly the cropping and linear fitting. Getting all the images to the exact same size is just bloody fiddly manually. Might try and learn PI's scripting environment to automate it.
  6. So I currently have my 8" Newt and that's permanently on imaging duty. I'm trying to now design a complete new rig centred on a Skywatcher 300P non-goto scope (which will be my first non-goto scope) for a telescope I can take out and use for visual observing while my imaging rig does its thing. Plus I'm going to an event (EMFcamp) in July where I want to have something a bit more outreach-friendly alongside the imaging rig! A 12" truss feels about right in terms of portability and storage space requirements. That kit list includes a Powermate 2x which I might use on the imaging rig but I'm mostly thinking of it as a more versatile way to get more flexibility out of a good eyepiece. I've also thrown in a Paracorr though this is mostly for the 8" to replace an MPCC Mk3 for imaging, and a Baader Steeltrak NT because the 300P only comes with a pretty basic focuser and I've liked the Steeltrak on the 8". While I'm trying not to break the bank I'm keen to go for a good-quality eyepiece - I much prefer doing a couple of things well rather than lots of things "okay" and I don't like buying something I know I'm going to upgrade/replace when I can! To avoid things becoming too expensive (more than they already are) I'm only looking to pick up one good eyepiece to start things off on this rig. I've got the 28mm that came free with the 200PDS, plus a Pentax 12mm. I don't find myself reaching for the 12mm often. However, I'm struggling to visualise how, say, a 17mm TV Nagler would look in that dob compared to my 28mm in the 8". I've got little experience with "serious" eyepieces like the Televues and not so much experience in visual observing anyway. Basically - any advice for the best focal length to go for as an all-rounder EP given access to a 2x Powermate? Edit: Forgot to add, I'm also keen to stick to the TV eyepieces for the Dioptrx support as I wear glasses but would prefer not to and use a Dioptrx lens to correct my astigmatism...
  7. I only lost a smattering and I have originals for the lot. For those looking for more reliable backup methods, if you've got a reasonable internet connection (>20Mbps down) then online backup is probably the way to go. I use Backblaze ( https://secure.backblaze.com/r/01u648 for a shamelss referral link that gives you and me a month off, https://www.backblaze.com/ otherwise ) and have successfully restored from it once or twice when a disk failed. Doing local backups onto a NAS/mini-home-server is fine so long as you're maintaining it and it has redundancy. And don't forget that RAID/mirror disks are not a backup - it just buys you time to fix a drive. Amazon S3, which Astrobin uses, is highly resilient and won't lose your data - but if you accidentally delete it, it's gone! I use Backblaze in addition to my main store which is a ~30TB 16-drive array using ZFS, which can tolerate 3 disk failures before I lose any data.
  8. Still getting to grips with mosaic processing. This is just the L - and only 5x120s in each panel since I faffed around doing RGB capture too. Should really have stuck to L alone. Focus doesn't look great in retrospect - I've been using Ekos' full frame autofocus with the SEP star detection but I think might do better with single star autofocus.
  9. Packed up here. Spent some time fiddling with a USB GPS module and got it working reliably with gpsd so that's all hooked up again and working. Mount was behaving very oddly after upgrade - axes just continuing to run rather than stop even after motion stop command, which is a bit worrying. Hopefully no harm done to anything - but drove home the need to sort out a proper permanent pier-side camera so I can see what's going on from my warm workstation upstairs and at least leg it out there as soon as something goes wrong! Edit: Some good frames, but one panel was heavily hit by cloud. Did a quick stack of one of the good panels' L frames:
  10. Spent a good half hour trying to build debian packages from source before realising there's now official packages for buster on the Pi4. Happily since I built my homebrew minimal install for Pi4 as deb packages, adding the repo and a quick apt upgrade has done the trick! Time for a quick test and then off to sleep.
  11. That's my plan! Going from 1.7.9 to 1.8.4 now.
  12. All done with my admittedly shallow mosaic acquisition for the night, using the rest of the evening to run INDI updates on the telescope Pi while it's still powered up.
  13. The TG365 covers work great but I would try and get everything sealed up as well as you can and ideally get some dessicant into the tube of the scope if you're leaving it outside for an extended period.
  14. I had this exact problem and I had an online laser cutting company cut me a rear cover which is held in place by the small collimation locking screws - they don't seem to do much good anyway and I've not missed them. You can still adjust the primary collimation knobs, though it's easier to get a firm grip by taking the plate off first - only takes a minute. I used https://www.ponoko.com and I've attached the file I sent in. I've not had any worries about light leakage around the primary since. Cost about £10 I think. The before and after in daylight: tubecap.svg
  15. Managing 1.1" RMS total at the moment here, which given my PA is out of whack is doing alright. Images looking alright so far - I've been doing a 4-panel mosaic on M81/M82 in LRGB, 5x120s to start. So far so good! Hoping I can finish all the panels once tonight and might try and do 5x120s L on all 4 in addition to that.
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