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Everything posted by Rusted

  1. Hi, I have collected several parabolic dishes for remote [British] satellite TV reception over the years. Over time the Astra 2 footprint regularly shrank below worthwhile reception here on the Continent. Unperturbed, I regularly increased the size of my [secondhand] "dishes" to achieve modest reception at specific times of the day. I still have 1m offset. Plus 1.8m [GRP] and 2.3m prime focus dishes. The latter a professional quality aluminium dish with reinforcing cage and massive altaz mount. All are no longer required. So could become oversized [Olympic sized] bird baths.
  2. I spent the entire day trying to resolve the multi-spot AR12814 in very soft seeing conditions. I should have had a proper look around much earlier. It was sheer luck I spotted Nigella's infamous Tower prom.
  3. Bagged this before lunch. Loads of cloud today! Weird, patchiness above the limb. Swapped Lunt BF for PST BF for more contrast.
  4. Another morning freezing in the obs. It has just reached 50F/10C. Seeing soft. Thick cloud wandering over.
  5. I bought a 150mm f/10 iStar objective to replace my old [secondhand] Celestron F/8 with internal GPC and sub aperture D-ERF. F/10 directly matches the PST etalon without needing further optics. Though I had to buy a larger Baader D-ERF [160mm.] Just to stop me setting fire to aperture stop rings in the dewshield. Solar imaging, even with PST mods, is not a cheap hobby!
  6. Interesting you should say that. I have used a PST etalon with both of my 6" refractors. The original blocking filter is far better at proms than the Lunt B1200S2 which I bought later. While the Lunt is [usually] far better at surface detail. Seeing permitting of course. The PST BF lets far more light through [than the Lunt] allowing a much lower gain increase for pulling out the proms. The extra gain required by the Lunt spoils the contrast for proms or seriously slows the FPS if the gain is left alone. Peter Drew has repeatedly mentioned that the relatively tiny PST BF is wel
  7. Thanks everybody. The seeing just did not support "serious" imaging. Imppg saved the day again. I was still trying after 6pm but the cloud was battling with the trees for submission. Of course it is clear now that I have packed up and the trees have won the day.
  8. Hi Stu, I just had a look in white light. At least four dark spots in my old Vixen 90mm/f11 with Lunt wedge. The sun has come back out again after loads of cloud but the seeing has gone completely mushy in H-a.
  9. A sunny morning had me back in the observatory. Nothing worked! Flat batteries and Firefox madness. I managed a couple of poor captures through clouds but nothing since.
  10. I saw a complete chain of Starlink satellites crossing the sky one night. Even after sixty years of amateur astronomy it was completely surreal! They too disappeared into the Earth's shadow. It is rare not to see some satellites when you enjoy dark skies. May I recommend a pair of binoculars to allow you to see more? 8x40 is a nice size. Light to hold and carry and can be used to admire the sky, the view, birds and animals. The modest magnification avoids exaggerating any handshake and makes finding stuff much easier. Keep looking up and be safe.
  11. Nice! Ideally, you should weigh both [complete] OTAs and then space them away from the DEC axis. To balance their moments just like a simple see-saw calculation. Mass x distance from the axis. I used a crossbar on either end of the saddle. Then placed the heaviest 180mm OTA closest to the DEC axis. The lighter 150mm was then spaced on the other side of the DEC axis spaced to balance the pair. It worked. With three smaller OTAs you'd weigh all three. Place the heaviest in the middle of your two crossbars. Then add the balanced OTAs. Carefully spaced on either side according t
  12. I should have said more clearly that the balance problem is applied torsion around the DEC axis. Some people add a weight on a stalk at right angles to the saddle and DEC axis. I tried that but ended up calculating the moment of the OTAs around the Dec axis as if it were a simple see-saw.
  13. I have hung three refractors 180/150/90mm from my big DIY GEM but it needed very careful balancing. Get it wrong and you introduce serious asymmetric imbalance [torque] with different sky pointing positions. I'm not talking about simple balance around the Polar Axis or even the DEC axis. Though that needs to be correct. I "wrap" my OTAs around the cradle to avoid adding too much moment. Main OTA flat on the saddle. The other two each side of the saddle. Fortunately I have a channel shaped saddle. You could try getting a suitable bit of channel to fit on your saddle if the idea app
  14. One rural neighbour had 19 insecurity lights at the last count. The next along has his very own "Close Encounters landing strip." Another left the carport lights on three years ago and still they remain on. So I took up "solar" and no longer care about local light pollution.
  15. Slightly off-topic but the absence of aircraft must be worthy of some unique research into other side effects. Atmospheric, cloud formation, albedo, jet stream, bird migration and song and behaviour, where noise is a factor? We see fewer trails per month now than we did in an hour pre-2020. Always high altitude back then and usually without audible sound thank goodness. Persistent trail conditions would have the sky liberally criss-crossed. It was interesting to see aircraft cross the sun. Leaving thermally agitated trails, drifting away.
  16. Very nice. Even better as a JPEG. So everyone can instantly admire your skill.
  17. Well done Nigella! It looks as if NASA will be envious as soon as you get some favourable seeing.
  18. Get cracking! There is no absolutely excuse for recalcitrance with a shiny new camera! Especially a shiny new ASI1600 bright red Roundtoit! Get a fast imaging laptop with SSDs and lots of USB3 ports and you won't regret it. I used Samsung T5 external SSDs on my ASUS N552V imaging laptop on USB3 cables and ports. They were always a nuisance dangling off the imaging desk and using up ports. I was constantly clearing them of videos at short intervals to make room for more. So I replaced the only [tiny] 256Gb SSD internal drive with a pair of internal 1TB SSDs: Samsung 860 &
  19. Many thanks for a brilliant idea! That's a very clever, alternative method. It also provides for an easy reach when cutting out the slit from the inside. Access to the outside of the dome has proved incredibly difficult. Even with the dome resting on levelling blocks on the ground. It never occurred to me to work from the inside. Thanks again.
  20. The problem: Draw two, straight, parallel lines, one metre apart, on a hemispherical [domed] surface for cutting out the observation slit. "There are no parallel lines in spherical geometry. Only great circles." So sayeth iTinerant. If you draw parallel lines on a dome to mark the observation slit then they will looked oddly curved. You can't just use a steel rule or wooden ruler. You can't stretch cord or tape between the start and finish points. If tensioned, string and tape will always adopt great circles. You can't assume lines a given distance apart are straight. Though th
  21. It has almost all been covered by previous posters. Like Peter, I am only interested in "close-ups." Except that I image. I used a very secondhand 6" f/8, internal 90mm D-ERF, PST etalon, original blocking filter and ASI120MC camera for a couple of years. Having had more fun, more often, than in all of 5 decades of the dark side, it was time to invest more heavily. Now I use a 180mm Baader D-ERF, iStar 6" f/10 H-alpha objective, PST etalon, Lunt BF1200S, FT2535 focuser and ASI174MM camera. I had to make my own main tube but everything else is just screwed together from standard p
  22. If you skin the outside of the tube with CF you will lose your superb finish. Won't you?
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