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Hi,
I am trying to use APP for my astro stacking and processing. I have taken M81 60Sx91 and stacked it together. The resulting image is very noisy. I tried light pollution and background calibration etc. Nothing seem to work. I am not sure what is wrong. Any thing you can identify from this below stacked image, please let me know.
https://drive.google.com/file/d/19_iIuVXCs6akCze1HOXvVWF3KLsWBgF8/view?usp=sharing
Thanks,
Sathya
Your exposure time is 60 seconds? That may be one of the reasons as each image will then likely be close to the readout-noise levels of your camera. Do you use calibration data like darks and bias?
Yes. The exposure is 60s. I also use calibration frames. I have 16 darks, 16 flats and 16 darkflats. These were taken using ASI533 and WO GT 81 IV, GEM45. I used NiNa to capture.
By the way, I am in Bortle 9 area and I have not used any filters.
Yes. The exposure is 60s. I also use calibration frames. I have 16 darks, 16 flats and 16 darkflats. These were taken using ASI533 and WO GT 81 IV, GEM45. I used NiNa to capture.
By the way, I am in Bortle 9 area and I have not used any filters.
@Vincent-mod Any pointes to know what could be wrong?
Yes so the short exposure time, combined with light pollution and no filter will not help to get clean images unfortunately. I would advise to look into using a good filter and then going for a bit higher exposure times.
I took around 400+ images each 60S with IDAS D3 filter. I still see the images are noisy.
https://drive.google.com/file/d/1Lz4aFgblrdRIK7vkU2eM5ObFTqQDQp0B/view?usp=sharing
Here is the original fit image after stacking in app https://drive.google.com/file/d/1XyS9syqWMYcLgsDrP2W9vSuR5ejr4a1E/view?usp=sharing
What am i doing wrong?
You're exposing a bit too short as I mentioned above, this means you're close to the noise floor of the sensor and that will give noisier results. For this target I would go for at least something like 3 min per sub, longer if possible. I would also add more calibration data, minimum of 40 darks, 60 bias. Also, the light pollution in your area seems high and even with that filter is still quite strong, that doesn't help either.
Noise reduction via software is something for a future version of APP, getting the noise down with a better data gathering method is always better.
That said, I took your first fits file and applied light removal correction and I think that's about the noise level I would expect for 60s.
@vincent-mod Thanks. As of now, I don't have guiding so anything beyond 60sec, the stars start to trail. I'll get the guide scope setup and try again. I guess, this filter is no use so I would return it.
Thank you very much.
