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eshy76

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Everything posted by eshy76

  1. Hi everyone, This has been on my hard drive for some months, so nice to have finally got round to processing it! Shot over several nights in January in my back garden. NGC 281, also known casually as the Pacman Nebula, is a bright emission nebula and part of an H II region in the northern constellation of Cassiopeia and is part of the Milky Way's Perseus Spiral Arm. It lies about 9,500 light years from us and is 48 light years across. As the final version, I've gone for a crop, which I think holds up well, though I'll include the wider fov version in the next post. I used a more natural colour blend for this image: R = 76%*Ha + 24%*SII G = 100%*OIII B = 85%*OIII + 15%*Ha For some reason, I was not expecting much from this image, but the result looks like it will be one of my favourites...the narrowband data was really good! Captured using APT, stacked using APP and processed in Pixinsight. 5.4 hours integration time. Link to full details and higher res version. Thanks for looking!
  2. Yep done that one too....one to add to the slapstick astro mess ups...though not as bad as taking 20 mins to realize that the cap was still on my polemaster once...the hot pixels looked like stars on the ipad screen...it took me time to figure out why they weren't moving when I rotated the RA axis....!
  3. The way it works is that if you put a gain number in the little box on the camera tab, that will override whatever was in the Ascom driver pop up, for a single shot and for an imaging plan - *if* you haven't assigned a gain to each filter in settings. In APT's settings when you set up your filter wheel, you can add a couple of things per filter which are useful as defaults for every time each filter is used - (1) the focus offset, if you are using autofocus and (2) the gain. So I tend have 139 assigned to LRGB filters and 200 for narrowband filters for example. I then leave the little box on the camera tab blank to make sure it doesn't override the filter wheel settings I put in when an imaging plan starts. It works perfectly for me....APT's scripting is pretty powerful...I also used it to platesolve to another target (Goto++) and restart PHD guiding in the same night...worked fine. Glad it's working for you now!
  4. Hi there - this seems very odd - I have the same camera and also use APT, and I'm pretty sure the gain can be set higher than 100. I tend to use 139.... My first reaction to your post is that you might not have the right driver selected in APT....to check, click on the "Settings" button next to the camera name at the bottom of the APT screen...then make sure the ASI-1600 is selected specifically from the driver drop down menu in the Ascom screen that pops up. Personally I tend to set the gain using the Ascom driver (in the same "Settings" pop up) and leave the gain setting blank in APT itself - this is because in my filter wheel setup, I have a different gain associated with each filter and I don't want that overridden by the manual gain setting on the camera screen. Let me know if you need me to explain the above more clearly...happy to help!
  5. Yep another vote for SkySafari...has been my invaluable companion on imaging/observing nights in both the Northern and Southern Hemispheres. I also prefer its forward and backward time controls compared to the swiping in Stellarium (which is also a very good app).
  6. I watched the vid and read those posts yesterday - superb! The new stuff versus what I had read before was actually getting a number for light pollution and incorporating that into the equations. It was an impressive presentation and makes me want to dig deeper into Sharpcap, if its creator is so knowledgeable. Thanks again for sharing!
  7. Thank you tomato! I went straight to CMOS, so short subs is all I know...looks like Sharpcap does a lot more than just polar alignment...I need to take a closer look.
  8. By the way, NGC 4440 was the pretty barred spiral galaxy I was referring to earlier....you will be mine one day!
  9. Thank you! I really wanted to bring out the blues more but the data was not cooperating...in any case it's a nice data set to come back and add to. The background is a mottled black too - I actually think that is the beginnings of IFN (integrated flux nebula), but the integration time was too low and the light pollution too high to get close to bringing that out as pretty dust.
  10. Thank you very much! Something to devour this weekend!
  11. I hear you! The basic theory is that each sub should be long enough to drown out the read noise and with the really low read noise of CMOS cameras, that level is reached quickly with light pollution. Of course you can shoot longer than that for practicality, but if subs are too long, stars and highlights could get saturated. That is it in words - there are mathematical formula that try to calculate the optimal sub lengths! Those cameras have really good reputations - I was looking at a 071, but ended up getting a 294, which I'm still learning. I think the 071 has an APS-C sensor? Thank you for the kind words!
  12. Thank you - that sounds interesting - I like the theory side of things as a guideline to what I do! And I did not know that about Sharpcap...I've got the pro version for the polar alignment routine, but have been using APT for capture.
  13. Thank you! That is the golden question which I intend to find the answer to - with my level of light pollution, 15 secs at unity gain on my camera is more than enough for my Lum subs to drown out the read noise...so I've always used that sub length... ...which was fine for 200-300 subs, but this project really brought home the impracticality of stacking 1000+ subs. I just was thinking in terms of total Lum integration time (250 mins) and set the number of subs that way. As far as I am aware, SNR benefits of stacking enter the realm of diminishing returns from about 200 subs onwards...so going forwards I'm going to lower the gain from unity (139 on the ASI1600) to 76 or 0 to try and get sub length up to between 30s and 60s and hopefully more like 200-400 subs to stack. I can then answer your question fully. The 15sec approach benefits in terms of guiding being less critical, and things like clouds or planes or satellites not meaning minutes of data being binned. The Lum integration WAS beautifully smooth at least!
  14. Thanks! Yes - an incredible part of space. There is a tiny barred spiral in the bottom middle of the image which is just beautiful and perfectly formed...I'll focus on that one one day when I have some more focal length!
  15. Thank you! Yes indeed...so while I got, erm, stacking benefits, the practical side was an issue in terms of the time it took to stack on a good PC. I also didn't dare drizzle the integration - that might have taken 2 days!
  16. Hi everyone, This is Markarian's Chain shot from my back garden over three nights in late March. Probably the deepest single image I've taken in terms of integration time...which leaves me feeling my processing is not quite doing the data justice...maybe I'll come back to it. In any case, this is an incredible part of space; looking away from our galaxy reveals countless others! The crazy number of Lum subs took a whole day for APP to chug through and so I've resolved to lower the gain from unity going forwards to get more manageable sub lengths than 15 seconds! L: 1050 (!) x 15s R: 92 x 60s G: 165 x 30s B 165 x 30s....total integration time 8.2 hours. Captured using APT, stacked in APP and processed in Pixinsight. Thanks for looking! Edit: Link to higher res version
  17. From left to right - 1. Minix mini-PC - this runs all my imaging and guiding. I remote into it using an iPad via the little white travel router on top 2. Bottom - yes a lithium ion battery for the dew heater 3. On top of the battery is a Lacerta dew heater controller which measures the ambient temperature to regulate my dew heater. I velcro all this to a dovetail which is bolted onto the scope rings...I've since moved to a lighter dovetail, as the one in the picture was unnecessarily heavy. Next stop is to shorten as many of the cables as I can....
  18. Thanks for the clarification - when I said I wasn't scientific in PHD2, I mean I still tweaked the more "obvious" settings...but I haven't spent an evening fine-tuning all the settings to perfection for example! Here is a picture of my rig:
  19. Polar aligning with a Polemaster and using an OAG, I average between 0.5"-1" (pixels right? The number in brackets on PHD2). I've seen better guiding than that but not often. This could also be due to having the wrong settings in PHD2...I've not been that scientific with it.
  20. I would add a yes to this, I've had mine for a year and have been using it with a William Optics Z73 to great effect. I think it is hard to beat in terms of performance vs. weight vs. cost, if you are looking for a portable or beginner mount, as I was. You can see images from the setup from the Astrobin link in my signature...most of the pictures are with the CEM25P. Autoguiding is a must, though, 45 seconds was the most I could bear unguided, although I've seen some people get amazing results with 2 minute subs. Seems robust - used it in winter temperatures of -5C and also took it with me to Mauritius last year (I live in the UK).
  21. This was single shot taken with a Samsung S8 (Android) on my father in law's rooftop in Vacoas, Mauritius on April 18th. I was facing East/North East and was mesmerized by seeing Orion "on its side" for a Northern Hemisphere dweller such as my myself. No processing, just straight from the phone. The mountain is Corp de Gardes and was 3 miles away. Also visible are Castor and Pollux and I think also Alhena. I was imaging the Carina nebula when taking this...thanks!
  22. Hi everyone! I was lucky enough to spend Easter in Mauritius and managed to get a night of imaging in despite the tropical night time clouds! As someone who lives in the Northern hemisphere, the Carina nebula has always been a target I've coveted, but during my holiday, I also loved Crux as prominent constellation in the Southern sky. So when I ran into polar alignment issues with my Skyguider Pro, I decided to play it safe and go for a wider field, capturing both those targets rather than focusing purely on Carina as was my original goal. This was shot from my father in law's rooftop in Bonne Terre, Vacoas, Mauritius and my basic polar alignment meant significant field rotation, but I still got some usable data. Cropped, processed and finally upsampled. Data was shot at f/2.8 with a 50mm lens, unguided on an unmodified Sony a6500. 174 lights at 30 secs each = 1.4 hours of integration. Bortle 5. From the colours it looks like these objects sit right on the disc of the Milky Way and I know there is more in the picture I haven't mentioned! Thanks for looking!
  23. Thanks for this comprehensive review - I've had the same scope for a year and I love it! The only fault I found was an inconveniently placed focus lock screw which means I need to turn the scope upside down if I need the dovetail to extend beyond the focuser for balance. Very minor issue. Also would have been nice if the rotator was marked for degrees...available as a £200 extra!
  24. Hi there...I managed to get a rudimentary shot of this amazing target when on holiday last year in Mauritius (southern hemisphere) where Antares is high in the sky with all the planets! But in your case, a tool you can use is the Telescopius site (formerly dso-browser). Once you've clicked on a target, you can choose to see its transit for the current night or "monthly" at a certain time like 10pm - the latter shows the altitude of the target throughout the year - I think Rho peaked very low (15 degrees) around July to August in the Northern hemisphere. I hope this helps! Edit: I just checked the site - I searched for IC 4604 and at 11pm it peaks on June 28th at 15 degrees altitude looking from my location of Surrey. Good luck with it!
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