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Though M101 is a relatively large target it is quite dim and this required a significant effort to get detail into its core. I took 31hrs of 30sec exposures which I then thinned down to the best 18hrs of data. Processed in APP and PS it was tricky keeping the core detail that I had imaged from blowing out.
Lots of advice and lots of very small curves stretches was the key in the end. Hardly sharpened it much with noise reduction undertaken as and when noise just stared to appear during stretching.
As the sensor is biased towards red, colour balancing with green and more so with blue was also necessary.
Taken at Gain 200 with a UV IR cut ASI224MC uncooled camera, APM107/700 scope on an AZEQ6.
It’s a good little sensor if you have the conditions (cold nights) and use Flats, Flat Darks and take Darks every night as the sensor temperature varies being uncooled. For info, I found it ran at about 6 degs above ambient once it was steadily running subs off.
Hope you like it.
I tried imaging M101 here in our Bortle 5 neighborhood and it was sort of tough due to the light pollution but I think I was able to pull off a bit of data. My problem now is that I was able to increase the visibility of the galaxy through stretching but in the process the background noise also increased. I also noticed that my galaxy and stars are a bit orange/reddish compared to the other M101 shots which are kinda bluish in color. Not sure if this is being caused by my astromodded camera but I tried correcting it via Photoshop and this is the best "white balanced" image that I got.
Looking for some help in this group maybe someone can have a go with my raw file and share some techniques on how to improve my post processing. The stacking was done via DSS and the processing via Photoshop. I also used Gradient Xterminator and also Astrotools.
Here's my edit and I also attached the raw file so maybe you guys can try tinkering with it also. Also open for any suggestions or comments with my initial edit. Thanks! 😁
Light Frames: 189 x 1 min shots @ ISO1600 (yes I still don't have autoguiding) Dark Frames: 198 x 1 min shots Mount: Celestron OmniXLT CG-4 Telescope: Celestron C6N Camera: Canon EOS Rebel XT Hap-Griffin Mod Autosave.tif
I’m hoping a PixInsight guru can help me. I’m a PI beginner, but am having fun learning. My question is about the level of noise in my images. After integrating and performing an STF stretch, the resulting image always looks quite smooth. But it doesn’t take long at all – just a DBE really, maybe then a gentle stretch – for the image to become really noisy. And then a lot of my editing is centred on battling that noise. My camera is an ASI2600MC-Pro, which I cool to -10. For a recent experiment, I gathered 20 hours of data from 120s subs. With that much integration time, and the low-noise camera, I was hoping for lower noise than I actually got. (I am shooting from Bortle 8, however).
So my question is: are my expectations wrong, and actually the amount of noise I have is what’s to be expected? Or, have I messed something up in pre-processing or integration?
In case it’s useful, I ran SCRIPT -> ImageAnalysis -> Noise Evaluation on the image straight out of integration and got the following:
Ch | noise | count(%) | layers |
0 | 2.626e-01 | 18.39 | 4 |
1 | 1.037e-01 | 12.01 | 4 |
2 | 1.636e-01 | 11.10 | 4 |
I’ve also uploaded the file (1.16Gb) for anyone kind enough to help investigate further:
A very crisp and cold night. I added more luminance data and also collected some RGB for NGC 2841. There is now around 4 hours in L and an hour each in R, G and B. The subs are 114s at a gain of 139.
NGC 2841 is an unbarred spiral galaxy in the northern circumpolar constellation of Ursa Major. A 2001 Hubble Space Telescope survey of the galaxy's Cepheid variables determined its distance to be approximately 14.1 megaparsecs or 46 million light-years.
This is the prototype for the flocculent spiral galaxy, a type of spiral galaxy whose arms are patchy and discontinuous. The morphological class is SAa, indicating a spiral galaxy with no central bar and very tightly-wound arms. There is no grand design structure visible in the optical band, although some inner spiral arms can be seen in the near infrared.
The properties of NGC 2841 are similar to those of the Andromeda Galaxy. It is home to a large population of young blue stars, and a few H II regions. The luminosity of the galaxy is 2×1010 M☉ and it has a combined mass of 7×1010 M☉. Its disk of stars can be traced out to a radius of around 228 kly (70 kpc). This disk begins to warp at a radius of around 98 kly (30 kpc), suggesting the perturbing effect of in-falling matter from the surrounding medium.
The rotational behaviour of the galaxy suggests there is a massive nuclear bulge, with a low-ionization nuclear emission-line region at the core; a type of region that is characterized by spectral line emission from weakly ionized atoms. A prominent molecular ring is orbiting at a radius of 7–20 kly (2–6 kpc), which is providing a star-forming region of gas and dust. The nucleus appears decoupled and there is a counter-rotating element of stars and gas in the outer parts of the nucleus, suggesting a recent interaction with a smaller galaxy.
Equipment: Celestron 9.25 XLT at F10, Skywatcher EQ6 Pro GEM, ZWO 1600MM Pro, ZWO EFW with ZWO LRGB filters, QHY5IIC guide camera on Skywatcher 9 x 50 finderscope
Hi! So Ive found some pictures from an arxiv report in a database which I need for my project and converted them to fits files (The picture on the left). The one that was used in the arxiv report (picture on right) is a zoomed in picture of a galaxy in that picture, where its clearly visible. However when I try zooming in on the exakt coordinates of the galaxy in the fits image, its just plain black. I want the picture "raw", that's why I saved it as fits and not their pdf picture from report. Someone suggested first stretching the image for a more detailed image but some filters had to be used though... the only thing I can find on the tables of the images is that filter F160W was used. I have no idea how to move forward now, completely stuck. Would appreciate some help!