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discardedastro last won the day on September 15

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. Well, today the mirror tool's epoxy had cured and I thought I'd have a go at this actual grinding lark. The epoxy pour had worked well in terms of coverage but had leaked round just a little bit (I elevated it on three more tile segments) leaving a couple of raised spots - I ground these off with a sanding block prior to starting. I marked my mirror with sharpie just to give me a view on coverage, added some 80 grit and some water, and off we go... I only did a short session this evening before rinsing it all off, just to get my head around it all and go re-read all my texts/books with some practical knowledge in hand. The contact seemed pretty good by the end of the 10 minutes or so. I was quite gentle with the amount of force I applied, so wasn't expecting a lot of material removed. I used a ~40% chordal stroke, randomly moving the tool and more frequently randomly moving the mirror (mirror on top). This was the surface I was left with, which was quite uniform. So that appears to be working okay - just need to do some more now I think! The fact I'm now removing material has brought into slightly sharper focus my lack of measuring tools. I've got straight edges, of course, but my spherometer is still in my friend's lathe backlog. I'll have to fab something else instead at this rate. I need to get a surface plate in either case, which will have to wait for next month (for boring, practical financial reasons) - I'm aiming for a decent-spec 400x400 granite plate which should do for all the potential mirrors I'd make.
  2. Perhaps worth mentioning that ArchiveTeam (a fine bunch of data hoarders and collaborators with people like the Internet Archive) have a form to request archival of groups: https://docs.google.com/forms/d/1Z-lODnyXsE2kiu8uL01L--10nDq3b_lowT88aB447-E/viewform?edit_requested=true If you want something to persist, it's worth submitting it. https://archiveteam.org/index.php?title=Main_Page is their site if you're interested in learning more or helping out (if you've got enough internet spare - my gigabit symmetrical line does its part!).
  3. Bit of an unplanned capture of 27x300s (just over two hours) 7nm Ha which came out alright. Nothing special but thought I'd share nonetheless. Capture was with my usual 200PDS rig, processing was PixInsight following a pretty standard cal/cosmetic correction/subframe selector/registration/integration process, with some light deconvolution to sharpen up stars followed by some MLT denoising and MureDenoise, histo+curves to finish. I'm planning to do a reasonably long duration mosaic of the Heart in general, my first mosaic - some test overlaps below (forgot to crop before I registered, but it's a start).
  4. Clouded in here. As an aside, the next version of KStars will correctly ignore the FITS field, if set, when making mosaics - meaning you can't fall into the same trap I did! Jasem has already written and applied a patch.
  5. I couldn't get any better tiles but got some more promising (much finer) plaster, so mixed that up and poured a fresh tool; the plaster is Dentstone KD yellow. It mixed up a bit thicker than I'd anticipated and set fast, so I had to do some sanding to get the back reasonably flat once it had hardened. My 80 grit and tungsten carbide sanding tool both appear to have gone walkies so I ended up using some 120 grit - took some time but got it pretty well tidied up. Weatherproof plaster with a slightly lower hydration is probably ideal - I'm not sure how the Dentstone would hold up very wet. Might mix up a small billet and soak it, see how it copes. I've done a first coat of epoxy using a polyester resin for the sides/back, so that should do for waterproofing and help level the back - I'll see how it looks after that coat and give it another coat if it needs it. Messy process so far, so the potting tray is paying off; the respirator, while not (as many have noted) a critical safety tool does help a bit with all the dust kicked up by sanding and the smell of the epoxy. I've gotten plenty of use out of my stash of nitrile gloves. If the epoxy's set well and completely covering the tool then tomorrow will be the first day of grinding!
  6. Absolutely. Checklists are great in hindsight. I keep meaning to make a halfway decent checklist app for this sort of thing.
  7. Lots of images of the same place with the right headers. The capture spec was incorrect - because it contains the FITS reference (which made sense for me to set, when I was setting up a job initially for a single shot, and then I didn't remove when I converted that job to a mosaic). Each mosaic job spec looks like: <Job> <Name>heartnebula-Part1</Name> <Priority>10</Priority> <Coordinates> <J2000RA>2.58407</J2000RA> <J2000DE>60.8758</J2000DE> </Coordinates> <FITS>/home/james/Pictures/scope/2019-10-19/Light/H_Alpha/HeartNebula_Light_H_Alpha_300_secs_2019-10-19T21-36-44_010.fits</FITS> <Sequence>/home/james/Pictures/scope/2019-10-19/Mosaic/heartnebula-Part1.esq</Sequence> <!-- more stuff --> </Job> ... but should just be: <Job> <Name>heartnebula-Part1</Name> <Priority>10</Priority> <Coordinates> <J2000RA>2.58407</J2000RA> <J2000DE>60.8758</J2000DE> </Coordinates> <Sequence>/home/james/Pictures/scope/2019-10-19/Mosaic/heartnebula-Part1.esq</Sequence> <!-- more stuff --> </Job> So the KStars scheduler dutifully did what was asked, and plate-solved the FITS file to get exact co-ordinates instead of trusting the values set in the Coordinates block. So, lots of 300s exposures of Melotte-15. Not a terrible thing! Just running a 3x300 sequence now on the same mosaic job without the FITS file set and it's working fine. Lesson learned, bug filed - definitely odd behaviour (though arguably user error!)
  8. Well, argh. Left the mosaic jobs running and went to do some other stuff. Thought it was odd that the images hadn't changed much throughout imaging so grabbed a few "tiles" down and found everything near-perfectly aligned. Turns out if you leave the FITS field filled in in the scheduler when creating a job to use for the mosaic tool in KStars, it'll copy that FITS file setting to all the jobs the mosaic tool generates, which then over-rides the coordinates and forces plate-solving against the FITS, so all the jobs solve to the same coordinates. Doh. Bug raised: https://bugs.kde.org/show_bug.cgi?id=413216 - bit annoying!
  9. Looks like a couple of hours of clear sky still in the forecast so letting the mosaic jobs run on. Doing a 3x3 mosaic with 10% overlap, 10 frames of 300s Ha each, as a first try at making a high-res image of the Heart Nebula - never done a mosaic before but with the new mosaic tools in PI 1.8.7 will be interested to try. Won't get everything in tonight but enough to do a bit of processing I hope.
  10. Clearish here, so cracking on with some Ha, starting on Melotte-15 but thinking of trying a bit of a mosaic capture tonight.
  11. So I've never done any solar imaging but have always fancied giving it a go. The Mercury transit next month seems as good as excuse as any. I've got a 200PDS/183MM setup and my thinking is that I could take a standard Baader solar filter and with that use my existing setup, which means I get to reuse everything. That seems like the cheapest option at ~£120 for a filter and a tilt adapter to mitigate Newton rings. I've got a 7nm Ha filter in the wheel as well as some LRGB. Would this be a sensible approach to do some basic imaging of the sun and spot Mercury? What else should I consider getting for my budget solar setup?
  12. Yep, moon's up. Not sure why I bothered with LRGB. Ho hum.
  13. Packed up. Frames fairly meh, but some halfway acceptable Ha to add to the store at least. Bright skies with very occasional clouds.
  14. Spent 2 hours trying to unbreak my network which decided to spontaneously develop a fault of some sort after 300 days of uninterrupted stability. Grah. Finally up and running. Picked on M33 even though it doesn't quite fit in the frame because soddit, it's something.
  15. https://www.canford.co.uk/CANFORD-RJ45-CAT5E-SCREENED-PATCHCORDS-Using-Cat5E-F-deployable-cable https://www.canford.co.uk/Products/31-850_CANFORD-CAT5E-F-CABLE-Black is the cable used. It's standards-compliant and will carry a gig at the usual distances, but it's stranded-conductor and so flexes really easily.
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