Alexp

Ahhh thank you, sry, I misunderstood the guide rate as per your advice. Thank you, I will try that out. And yes, I will check the focuser and see what I'll find inside! Thanks again very much! Cheers

Thanks for your analysis and input alacant and thank you for having a look at the images. Oddly enough I usually always had a higher guide speed, between 1 and 2 seconds. But just to see the difference I once tried a lower guide speed and then I saw that overall with my AVX seemed to have performed at a lower RMS error. Sometimes I still increase the guide speed before an imaging run to see if the RMS error lowers itself, but oddly enough the RMS error always seems better at that low guide speed. I have a few upgrades planned for the scope, a new spider vane and primary mirror mask with a new secondary mirror holder, a new focuser tube (which one is best for my 150PDS I do not know yet, I'd like to budget around €300 for that), and a motor focuser. I still don't believe the mount is the issue so I'll stick to my AVX after having upgraded and regreased it. I do not know why I haven't thought about the comacorrector being the issue, guess I'll put that one on my to-buy-list as well. I do not want to go and get all of the upgrades at once so I rather thought I'd prioritise based on what item will have the most effect on reducing the egg shaped stars (and since I saw one of cuiv's recent videos about his upgrades to his new newtonian, he also talks about the low quality of the focuser, which led me to think that might be an issue with mine as well). I don't know why I haven't thought about the coma corrector itself 🤔.. I will still have a look at the inside of the focuser but I guess I will get the upgrades for the newtonion just as I feel like doing it. Thank you for your kind words and help! In general I feel quite fine with the images, but I reckon I should be able to do better with these upgrades including a new coma corrector. Cheers and kind regards

Hey guys, it's been quite a long time since anything has happened here because of all this bad weather, but I guess many of us have the same issue in Europe. Anyway, last time I was able to image an object, I went for IC 5146 and gathered around 150 minutes worth of "usable" light frames at 60 sec each. In general, I always have eccentricity issues, my stars are always egg shaped around the corners. I have, unfortunately, no experience or clue whatsoever as to what the problem could be, but I believe from looking at the images that there is a pattern to the star shapes across the images but I wouldn't know what the exact issue in the optical train is so I do not know how to solve it. My setup is a SW150PDS with an ASI533mc pro attached on a Celestron AVX. I believe that I am reaching the limits of the Celestron AVX weight wise but I doubt guiding was/is the issue. For that particular night of imaging I had a total RMS error of 0.73" according to PHD2 logviewer (I attached the guiding log here). I do have a resolution of 1,03"/pixel with the ASI533mc pro and the SW150PDS and from gathering as much information as I can I am aware that achieving half of the resolution as max RMS guiding error would be better, but I doubt that this is the main issue here? The optical train itself - beginning with the camera - is my ASI533mc pro -> filter drawer -> baader MPCC -> screw adapter for baader MPCC to the focuser tube of the SW150PDS. At some point I bought the screw adapter for the Baader MPCC because otherwise when using it with the regular focuser tube it would pinch the baader MPCC, hence the solution was to buy the screw adapter for the MPCC. To find out if the egg shaped stars are consistent over the entire imaging session I compared the stars of the image with high eccentricity (and a low fwhm) with the stars of the image that had a low eccentricity (and a high fwhm) -> the same issue is visible. According to ASTAP there is a tilt in both images, I have attached the image analysis of astap, and also, I have attached the unprocessed .fits files as well in case anyone would want to take the time and look at the two images. I do believe the telescope was collimated well enough when checking with my cheshire. Is there anyone who could be so kind and look through these images and help me find what the issues are? Is the guiding error too high for the resolution? Could it be that the lousy focuser tube has a tilt and I should get a better one or could it be bad collimation? With my current knowledge (and of that I have almost none) I am suspecting something with the focuser tube or could it have something to do with the screw adapter for the coma corrector? I hope I have added enough information for someone to look at and any help I could get would be highly appreciated! Have a nice day in the meantime, all of you!! Cheers, Alex PHD2_GuideLog_2023-09-10_205727.txt L_IC5146_12627_Bin1x1_60s__-10C.fit L_IC5146_12705_Bin1x1_60s__-10C.fit

Thanks! I'll have a look into that and see if changing some of these variables have a positive influence on guiding! Cheers

Thanks for your kind words Simon! I do think I would be able to get the details a tiny bit sharper once I solve the issues in my optical train. As opposed to buying my way out of the problems I always try to experiment, even in hopeless situations, just to see if there is a difference. Plus I am hoping that this way I will understand all the mechanical and software related issues a bit better. I always thought that it would be better to have longer exposure settings in PHD2 but trying it out differently once now really seems to have had an influence, at least for my setup and the circumstances around my setup. I was, however, not aware that it is possible to control more variables than just guiding exposure (guide exposure - correction issued - next guide exposure)? You are also using PHD2 and an AVX? I am assuming these settings are plainly visible and I am just not aware, which most often is the case for me ^^. Cheers, Alex

After many, maaaany months of not being able to image due to bad weather it has finally cleared up over the past month.. Even though there is only little astro darkness currently, I couldn't wait any longer since I really had the itch to image something in the night sky. There have been many pictures of it already, but I also wanted to have a go at M101 with the current visible supernova as I have never yet imaged an event like this. Altogether I managed around 12h of imaging time at 60s exposures in a Bortle 6/7 zone (unfortunately a lot of extra light from neighbours' windows) over the course of five nights with my SW 150pds and ASI533mc pro on my AVX (kind of pushing the weight limit on it for astrophotography). Oddly enough I found that decreasing my guide exposure setting from 2 seconds to 0.5 seconds in PHD2 gave me better guiding results on the AVX overall, which went below 0.8" RMS error. The stars are slightly egg shaped - with my half-knowledge I am assuming that this may be the result of (maybe) the cooling fan of the 533mc pro vibrating and bad collimation. Testing will be necessary to find and remedy the issue(s). After countless hours of integrating 730 frames on my laptop and post processing the final result in PI I believe I have a version now with which I am happy, though I might still try and image M101 with the ZWO duoband filter to add some Ha to this image. Comments and critique are very welcome, hope you guys like it and I wish you all clear skies! Cheers, Alex

Finally got round to image M63 in Canes Venatici, a galaxy I have been wanting to image for a long time, unfortunately we have very bad weather and true darkness is getting shorter and shorter but I guess all of us are facing this problem.. 🙈 All in all, I am surprisingly happy with the end result given the location where I shoot at (Bortle 6/7 suburban, but there are lights from apartments around me everywhere and there is not much of true darkness by now) and the usual blotchiness/red mottling of the background that I am often encountering and still figuring out (probably overcorrection of flats and/or light pollution?). The galaxy was imaged with the 150PDS and the ASI533mc pro with a UV/IR cut filter and the Baader MPCC Mark III coma corrector on my Celestron AVX. Guiding was done with the SW 9x50 scope and an ASI120mc. I really like the FOV given by the combination of the 150PDS and the ASI533mc pro for galaxies. Altogether I managed to get 454x 60sec subframes (100 gain, 13 offset at -10°C) on 15.05., 18.05., and 25.05. Dithered every 2nd shot, 50 flats and 50 darkflats per session as I still keep trying to work out proper flat settings for my image calibration. After blink and further rejections in SFS 239 subframes remained for postprocessing for this image. I used APT for imaging, PHD2 for guiding and PI for image integration and post processing. The processing steps after integration were the following: Linear Processing Phase: Dynamic Crop Channel Extraction LinearFit Channel Combination DBE Background Neutralization Photometric Color Calibration SCNR green TGVDenoise with a mask for noise reduction MMT with a mask for noise reduction Nonlinear Processing Phase: HT to stretch ACDNR with a mask for noise reduction Starnet v2 to remove stars On starless image MLT to reduce background color with range mask Curves Transformation with S-curve stretch for contrast HDRMT with range mask LHE with range mask MLT with range mask to sharpen details Extract lum and use with LRGB Combination to increase saturation Minor Color Saturation with range mask MLT for noise reduction with lum mask On starmask Curves Transformation for saturation MT to reduce star size On Final image Pixel Math to combine starless image with star mask Topaz Denoise for noise reduction, which may have introduced some artifacts but only if zoomed into the picture Thank you for looking at it, I hope you like it, comments and critique are of course very welcome! Clear skies to all, Alex

Since this challenge is about Galaxy clusters and I just finished working on Hickson 44 I thought I'd add mine as well even though all the images here are really, really amazing to look at. This was the first time I used the ASI533 on a Galaxy cluster, I have had the camera since three months now and I am really happy with it. This galaxy cluster was shot with a 150PDS sitting on an AVX and an ASI533mc pro with a ZWO IR cut filter. Guiding was done with an old ASI120mc and the SW 9x50 finderscope. I shot a total of 12h 15m, of which I used 10h 57m, all shot on 20.03., 21.03., 23.03., and 25.03. The light frames were 180s @ 100 gain, 13 offset, and -10°C, dithered every shot. All of the frames were shot in a Bortle 6/7 sky, unfortunately there are a lot of windows with lights on in the night (what are they all doing if they aren't shooting the night sky??). All of the processing was done in PI. Integrated with local normalization in Pixinsight, in the linear phase I did a dynamic crop, followed by channel extraction, linear fit to the weakest channel, DBE x2 to remove gradients, TGV denoise and MMT based on Jon Rista's tutorial. For the non linear phase I stretched the image with HT, inbetween stretching I used ACDNR for some further noise reduction, followed by starnet v2 to work on the starless image. On the galaxy cluster I used HDRMT twice with different settings, then LHE, s-curve stretch for contrast, curves on saturation and selective color boost using colorsaturation. MLT with a lum mask to sharpen details, saturation boost on stars, followed by pixelmath to combine the starless image with stars. The final step was MLT with a lum mask for noise reduction. Clear skies to all and once again, all of the images here are amazing!

I think this is one of the nicest M101 images I have seen. Looking forward to seeing the version with added L and Ha.

You're welcome. Your image is honestly really nice and has a great amount of detail. I hope to be able to produce similar images sometime in my life ;). Hopefully sooner than later. Ah yes, I barely noticed UGC 5086. For 2h worth of lightframes I'm quite happy with the result, I plan to add more data to this stack to hopefully get some more details but I was not really expecting this for 2h. Thanks for the tip concerning EZ suite, I have not yet used it and I will look into it, thanks for the link. Cheers

This is my first time finally posting an image here that I'm somewhat happy with 🙃. Managed to get 2h @60s exposures of NGC 2903 with my ASI533 and my SW 150PDS on an AVX. I tried this target already a week ago but I ran into weird issues with overcalibrating flats and walking noise. Thanks to help of @wimvb who pointed me into the right direction I was able to mitigate these issues now with this set of lightframes. The only issue that I still have remaining is the background, which seems kind of patchy blue and reddish over the picture. I'd believe that may result from a combination of the light pollution from where I'm shooting at (Bortle 6/7 suburban, lights from windows all around my setup), and a somewhat sloppy way of creating masks for noise reduction (following Jon Rista's noise reduction routine in PI)? In any case, I am glad that I was able to resolve the walking noise and flats-overcorrection issues with some help so I can continue to improve at taking and at processing deepsky images. It's certainly not as detailed as @DaveS' or @tomato's beautiful versions of this galaxy, but the galaxy itself already does a great job at looking nice 🙂. Cheers

My laptop just finished integrating M1 from the same night with the same flat frames and the same dithering settings. The image is stretched a bit more than NGC 2903 but both overcorrection from the flatframes and the walking noise is still visible. I will now try and calibrate the light frames with the new flat frames to see if this problem will be mitigated then, which also means that only walking noise should be left and that problem I can only resolve in the next imaging session. Cheers, Alex

Thanks for the tip. Currently image calibration is running on M1 that I shot the same night. If everything is as it is I should be at least able to see the same issues there as well with the same flat frames and with the same dithering settings that I had. This may be seen as unnecessary but I want to see if I have the exact same issues there. I will afterwards blink the pre registered images of M1 and NGC 2903 to see if the stars drift in any one general direction as second confirmation. Concerning your tip with the t-shirts, I did exactly as you said shortly after I wrote my last comment. With three t-shirts I at least managed to get the flat frames to 0.14s and I already shot the corrseponding darkflats at -10°C to those as well. I did not move anything in the optical train since having shot both targets so I assume the new flats should also work. After reproducing the error on M1 and after blinking the images I will try and calibrate the light frames with the new flats and darkflats to see if only the walking noise is left. I thank you for your input so far! Cheers, Alex

You may be right there. I believe it's either that or the camera may have also been completely overexposing? Either way it would be interesting to find out how the camera is connected to the scope

I am honestly not sure how well your setup will work together with a DSLR camera and how much knowledge you have already built up in astrophotography. Afaik your mount is not motorized, which means you will not be able to take long exposures as your mount can't track objects in the sky automatically to counter Earth's rotation. I guess it depends on what you want to shoot? Maybe it is possible to shoot some objects by taking many and quite short exposures (half a second --> if you are not familiar with the 500 rule, google it to find out what that is, your camera has an APS-C sensor which means you must take a crop factor into account for the 500 rule), but I am sure there are many more qualified people here that may have a better answer than I have. Apart from that, how is your camera connected to the scope? Are you using something like this 2" adapter or this 1.25" adapter? If the screen is blank does that mean black or white? It seems like you may be overexposing completely or are shooting in some other mode than manual? If you want to delve into astrophotography, you will always take pictures in manual mode. Concerning the ISO of your camera it depends I guess. With my scope and my tracking mount, when shooting objects like galaxies or star clusters I was able to take 180 seconds exposures with ISO 400 or ISO 800. If you want to take pictures of the Milky Way, you will need a much shorter focal length and shoot at a higher ISO. Also, set the focus to manual instead of automatic. Before you actually start taking any pictures, it's important to be in focus of course. Here it is quite helpful to google Bahtinov mask. Apart from that you can simply try liveview and change the focus until you believe you have the smallest stars on your screen (I'd say though this is the least effective mode on achieving focus). If you are not yet familiar with astrophotography you should also google image stacking and calibration frames, there is tons of information available and many programs (Deep Sky Stacker, for example) are free to use.