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drjolo last won the day on July 23 2018

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About drjolo

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    Star Forming

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    Nieborowice, Poland

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  1. I do not hunt specifically for quasars, but quite often scan my existing images for distant objects. I have found objects over 12 billion light years away three times already. First one is in the M105 galaxy trio area. It is SDSS J104718.26+130318.6 quasar 12 billion years http://skyserver.sdss.org/dr9/en/tools/explore/obj.asp?id=1237661068716474941 : Another one is close to NGC4244 galaxy - SDSS J121510.36+375811.2 - http://skyserver.sdss.org/dr13/en/tools/explore/Summary.aspx?id=1237664338792350092 - 12.4 billion years: And another 12.4 billion years target - http:
  2. Yes, dithering must be performed between the shots (or between the shots group). Then is usually requires some time to stabilize guiding after dither command.
  3. It may, but it does need to interfere - depends on camera behavior. In my estimation most probably it will not cause any problems. I just wanted to point out the root cause of some problems, because many astrophotographers are not aware of it and trying to replace cables, USB hubs, power supplies, and the ground loop is still present in the system.
  4. Yes, because you have two paths for the ground signal: first: power supply cable -> DC hub -> 5V power cable -> USB hub -> USB cable -> camera second: power supply cable -> DC hub -> 12V power cable -> camera The 5V voltage is of course separated from the 12V voltage, but they share the same minus (ground), unless the DC converter inside the hub is isolated, but as I mentioned it is not probable. But in your setup it will be easy to detect. If any problems with camera signal or connection occurs, you may just power the USB hub with separate 5V su
  5. So as I understand: you will have one 12V PSU that will power DC hub one 12V DC hub output you will use to power QHY8L one 5V 3A DC hub output you will use to power USB2.0 hub That should work, but you will have one potential ground loop, because ground (voltage minus) will be delivered to the camera with two cables - 12DC power cable and USB cable. It may, but does not need to cause troubles, depending on cable and connection quality, and also on how camera deals with such scenario. The ground loop in general happens, when the same signal (ground in this case) is connec
  6. In my experience 0.5x guide rate is a good starting point for HEQ5 and EQ6 mounts.
  7. Thank you! I would love to have more nights like the one I captured data for M63. At my backyard observatory clean air and good transparency are the only ways to fight LP (at least for LRGB imaging).
  8. I am not sure if you can attach regular eyepiece to this guidescope, but maybe you can use guide camera as electronic finder? A few seconds (2-5) exposure at higher gain should reveal more stars, than you will be able to see with an eye. However field of view will be smaller.
  9. Last year was not the best in terms of total number of subframes I was able to collect, but still, I captured a few galaxies. Most of them are well known or very well known targets. But maybe one or two are a little bit more exotic All images were captured in my backyard telescope under moderately light polluted sky. Equipment: Meade ACF 10" f/10 with Astro Physics reducer, QHY163M with Baader filters and EQ6 mount. Stephan's Quintet. Conditions were decent - good transparency and good seeing, but the weather did not allowed to capture more data. So the total exposures are L 120x2 minute
  10. I am currently also trying to make similar decision - select filter for 294 color camera under moderately polluted sky. I am thinking about Optolong L-Pro filter. There is one more aspect of filter if we consider OSC camera - color balance in the result image. If the filter passes broad lines, then color balance is affected less. For UHC filters color balance is affected more, and for extreme duo/thee narrowband even more. At least it appears to me like that basing on some internet research and findings. Found at https://www.cyclopsoptics.com/filters/optolong-l-pro-filter/
  11. It is my friends' mount, and as far as I remember he uses Cartes du Ciel. Eventually some time ago we found out the root cause of this problem. It is the stepper controller chip (DRV8824 or DDR8834 - I do not remember now) that provides non-linear current when microstepping. When we connected both motors to another board (AstroEQ) then they work perfectly fine.
  12. I would like to share with you my measurements of iEXOS-100 mount stepper motor tracking rate recorded in short time scale. The reason we did such measurement was permanent problem with elongated stars, even at short 1-3s exposures during focusing. Together with friend of mine we took off RA stepper motor cover and noticed that stepper motor movement during tracking is not linear. I put Allen key to the RA worm shaft to better record this effect: It did not look good, so I decided to actual measure the period of that wobble. I measured that during 24s of movie axis wobbl
  13. Thanks! You don't need a direct sunlight to take Sun spectrum - it is enough to point the spectroscope inlet to the cloudy sky. I took my first spectra ever this way It was captured with IMX224 camera
  14. I have been using LowSpec already some time with 600 lpmm grating (from Edmund Optics). Recently I have purchased 1800 lpmm holographic grating from Thorlabs to be able to analyze deeper Ha lines. This grating has pretty large dispersion, so I needed to saw a little (about 1mm) of the grating holder to be able to reach the very red end of the spectrum. Other than that all works fine, and here are first results compared to the ones captured with the same LowSpec device an 600 lpmm grating. Sun Mg triplet at with 600 and 1800 grating and different slits Sun Na doublet with
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