wimvb Posted March 18, 2019 Share Posted March 18, 2019 Recently I posted an image of ngc 3310 (aka Arp 217) in this section. In the mean time, I have had the opportunity to gather more luminance data for this target. I'm at the moment at a total integration time of about 7 hours (3 hours RGB, 4 hours L). Unfortunately, the latest L subs were taken at a camera gain of 0, and not my standard 20. This means that they are somewhat underexposed, and weren't calibrated properly (I don't have darks at these settings). Anyhow, with the help of DBE and a lot of chiseling in PixInsight, I managed to pull out this image. Sorry about the background. When I've collected the proper calibration frames, I will do a better job of flattening it. While processing, I also noted that I'm now very close at revealing the very faint tidal structure around this galaxy. It shows a little better in the inverted and superstretched luminance master (towards the upper left of the galaxy). Ideally I would need to at least double the total integration time to isolate this structure properly. As a reference, here's an image by Adam Block, showing the tidal structure. https://skycenter.arizona.edu/node/320 Link to comment Share on other sites More sharing options...
Demonperformer Posted March 18, 2019 Share Posted March 18, 2019 Very nice. So will you be collecting more data to enhance the tidal structure further? Link to comment Share on other sites More sharing options...
wimvb Posted March 18, 2019 Author Share Posted March 18, 2019 1 hour ago, Demonperformer said: Very nice. So will you be collecting more data to enhance the tidal structure further? Thanks, DP. Yes, that's the plan. But for the next two weeks there will be too much light pollution, and the weather gods have other plans. By the end of April imaging season ends up here, so we'll see how much more I can collect. In my previous thread, Sara ( @swag72 ) mentioned that she's collecting data on the same galaxy. It will be interesting to see how she does. Link to comment Share on other sites More sharing options...
michael.h.f.wilkinson Posted March 18, 2019 Share Posted March 18, 2019 Very nice. I can certainly pick up some tidal structure there. I am currently working on a new tool for astronomers to detect very low surface brightness structures in astronomical images. It would be interesting to see what that could detect on these data (once calibration has been done). Link to comment Share on other sites More sharing options...
x6gas Posted March 18, 2019 Share Posted March 18, 2019 That's very pretty Wim. Link to comment Share on other sites More sharing options...
Demonperformer Posted March 18, 2019 Share Posted March 18, 2019 31 minutes ago, michael.h.f.wilkinson said: I am currently working on a new tool for astronomers to detect very low surface brightness structures in astronomical images. That sounds intriguing, Michael. Link to comment Share on other sites More sharing options...
michael.h.f.wilkinson Posted March 18, 2019 Share Posted March 18, 2019 54 minutes ago, Demonperformer said: That sounds intriguing, Michael. These are two comparisons to the venerable Source Extractor (SExtractor), vs our previous MTObjects version on SDSS images. SExtractor MTObjects: SExtractor: MTObjects: Clearly MTObjects captures much more of the low surface brightness detail, including the tidal feature in the pair of merging galaxies above. Full paper on that version here: https://www.degruyter.com/downloadpdf/j/mathm.2016.1.issue-1/mathm-2016-0006/mathm-2016-0006.pdf We are developing a new version within the EU SUNDIAL ITN, which should be more flexible, add more speed, and be able to classify objects, rather than only detecting them. I will post more details once the paper(s) are accepted for publication Link to comment Share on other sites More sharing options...
wimvb Posted March 18, 2019 Author Share Posted March 18, 2019 2 hours ago, michael.h.f.wilkinson said: Very nice. I can certainly pick up some tidal structure there. I am currently working on a new tool for astronomers to detect very low surface brightness structures in astronomical images. It would be interesting to see what that could detect on these data (once calibration has been done). Interesting. Thanks for the publication link. In my image, it isn't just the calibration that has to be improved. The bright star at the top of the image is mag 5.5. It causes severe microlens diffraction. In a "pretty picture" I have to replace that area with a low stretch image. I can post the original luminance here for comparison. Link to comment Share on other sites More sharing options...
michael.h.f.wilkinson Posted March 18, 2019 Share Posted March 18, 2019 45 minutes ago, wimvb said: Interesting. Thanks for the publication link. In my image, it isn't just the calibration that has to be improved. The bright star at the top of the image is mag 5.5. It causes severe microlens diffraction. In a "pretty picture" I have to replace that area with a low stretch image. I can post the original luminance here for comparison. Diffraction spikes and the like aren't the biggest problem for our tool. The main issue is that the background needs to be as flat as can be. It also assumes no stretching has been done, so an original luminance image is preferred. Link to comment Share on other sites More sharing options...
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