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glowingturnip

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glowingturnip last won the day on March 19 2014

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About glowingturnip

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  1. glowingturnip

    an odd dark image

    it's light-spill round the base of the tube, I get the same with my 200PDS, took me a while to figure out what it was. I solved it for me by getting a square of black-out-blind material off amazon, and then when I've done collimating i wrap it round the base and hold it in place with a bungee cord of the right length.
  2. glowingturnip

    The joys of an F5 newt instead of an F4......

    I've certainly no complaints with my new-ish f5 200pds. Out of the box it wasn't very well collimated, the secondary was longitudinally out of place in the tube and a bit squint too (but I did buy it in Spain - maybe they dropped it), but after an extended session with the cheshire lining it all up it keeps collimation well now. I set up and tear down each session, and only need a quick laser collimate to get it all back in line again. My coma corrector MPCC III spacing was a headache though, I've ended up a full mm longer than the recommended 57.5mm spacing for M48 threads and it's nearly all gone, just a tiny bit of coma left along one of the edges, but any more spacing and I wouldn't be able to screw it all together.
  3. glowingturnip

    Horsehead nebula in Narrowband

    love it, really like the colours. I'd echo the comments on the flame though, looks curiously flat and yellow compared to the rest of the image
  4. glowingturnip

    M16 from Astro campsite

    there's another, frankly very strange, filter you can do to your photos - here Sorry Carole !
  5. glowingturnip

    M 16 Ha

    no no no, I think yours is very good, not a lot between them to be honest. It just struck me as funny that we had almost exactly the same pic. But I think we both owe it to ourselves to get more data :-)
  6. glowingturnip

    M 16 Ha

    it was 9x600s Ha, darks flats and bias, equipment as per sig, Pixinsight. - only 9 exposures, hmm, didn't realise it was so few, I definitely need to revisit then. I'd normally want over 20. my initial thread was here: and then I had fun with star removal here:
  7. glowingturnip

    M 16 Ha

    nice pic. It tickled me, because I have almost the exact same picture: Eagle Nebula (M16) in Ha by Stuart Goodwin, on Flickr I'm planning to add some OIII to mine this summer, see if I can make a decent bicolour
  8. glowingturnip

    Cannot get good focus with OAG and Lodestar x2

    I have the same camera and OAG as you. Is the helical focuser a separate piece of kit, or is it that thing that just screws into the OAG and holds the guidecam ? I ended up 3D-printing a really thin spacer so I could keep it at optimal distance. I found that having focus too tight was actually counter-productive since all those edge-of-frame effects made the stars become double or triple lobed. Just slightly out of focus (outwards) for me brought it back to a nice round blob with a clear centroid. I use about 3s exposures in phd, which will probably help you.
  9. glowingturnip

    Question about a Light Panel for Flats

    looks same make as mine, so you'll probably be wanting to sandwich 2-3 sheets of plain paper between panel and scope too, otherwise it's too bright, which will help soften that spot too.
  10. glowingturnip

    Pinwheel Galaxy M101

    Here's my homage to galaxy season: 13x600s lum plus 12x900s lum, 24x180s each of R, G and B and 12x180s Ha used for chrominance only. Taken over 2 nights on 21st and 22nd March. Equipment as per sig, processed in Pixinsight (Cross-posted to the Galaxy competition forum). Capturing was a little fraught. On the first night things were fine, found a nice guide-star with the galaxy right in the middle of the frame and good guiding all night. However, the second night, with the galaxy in almost exactly the same position and orientation, but I just could not find a guide-star in my OAG. By the time I found one, the galaxy was way off centre, and I had to do some fancy footwork in processing to merge the two sets. Thankfully, I don't think you can see the join... I was amazed at the number of faint fuzzies in the background, so I made this collage taken from the uncropped image. I don't think I got them all either, there are loads of very faint objects in the pic that don't quite look like star profiles: This was my first attempt at this target. Which one do you prefer ? The Pinwheel Galaxy (M101) is a face-on spiral galaxy 21 million light-years away from earth in the constellation Ursa Major. M101 is a large galaxy, comparable in size to the Milky Way with a diameter of 170,000 light-years. It has a disk mass on the order of 100 billion solar masses, along with a small central bulge of about 3 billion solar masses. M101 is noted for its high population of H II regions, the pinkish areas in this image, many of which are very large and bright. H II regions usually accompany the enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force where stars form. H II regions are ionized by large numbers of extremely bright and hot young stars, those in M101 are capable of creating hot superbubbles. M101 is asymmetrical due to the tidal forces from interactions with its companion galaxies. These gravitational interactions compress interstellar hydrogen gas, which then triggers strong star formation activity in M101's spiral arms. It is in the M101 group of galaxies, distinct from our own Local Group, but also a member of the Virgo Supercluster of galaxies. The Virgo Supercluster contains at least 100 galaxy groups including our own, and is one of about 10 million superclusters in the observable universe. Comments and cc welcome, hope you enjoy ! Stuart
  11. 13x600s lum plus 12x900s lum, 24x180s each of R, G and B and 12x180s Ha used for chrominance only. Taken over 2 nights on 21st and 22nd March. Equipment as per sig, processed in Pixinsight (Cross-posted to the Imaging-DeepSky forum)
  12. glowingturnip

    autofocus with OAG guiding ?

    thanks both. I guess I'll need to be more careful with my polar alignment so that the star doesn't drift off in Dec when the guiding's off. I'm a set-up and tear-down person at the moment and usually let PHD pick up the slack in my Dec drift. Good tip on the sticky lock Sara, I'll look into that.
  13. glowingturnip

    autofocus with OAG guiding ?

    Hi all, I'm just starting to think about getting autofocus going on my rig. My focuser is a Lacerta Octo60 which will accept a focusing motor attachment which I can drive from SGP. However I'm guiding through an OAG using PHD, and was just wondering if the automatic refocusing interferes with the guiding ? I assume I can instruct SGP to turn guiding off during refocus and then turn it back on, but does that create any issues with lost guide stars or whatever stopping the session ? Cheers
  14. glowingturnip

    Synthetic luminance

    yes you can, I've experimented with various ways. Combining all the subs together in one super image integration isn't likely to work since some channels will be stronger than others so lots of subs from particular channels will get rejected, so you should probably run an integration on each individual channel first. The Pixinsight book suggests you can then produce a super luminance from your LRGB, or just RGB - linear-fit them all to the strongest channel first, then load them all in ImageIntegration, no rejection, but noise-weighted, and try that. I've not been too impressed tbh. Another method I've used - combine and whitebalance your RGB, then with the RGB working space tool, experiment with trying different weights for each channel before using the extract-luminance tool. You can see what weights you'd like by noise evaluation, the contrast-vs-noise script and visual inspection. If you have L as well, then you could mix that in with pixelmath - lum*weight+rgb_l*(1-weight) kind of thing. to be honest though, these days I just take lots of lum, and only use the rgb for colour.
  15. glowingturnip

    My 130 P-DS and a hacksaw?

    out of interest, does every sub show the same shape ? If I'd seen that in my subs I'd have assumed a tracking issue, but then the shapes would be different from sub to sub. Also, tbh, I suspect a lack of focus is exacerbating the problem
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