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Artefacts in stacked image
Hi - I am using an ASI294MC Pro and have stacked 30 light frames, with darks, flats and bias. I am getting small lines in red, blue and green across the image. See attached (its a low quality jpeg as the site didn't allow a higher quality tiff). I thought it may be hot pixels and have created a bad pixel map and also used sigma clipping in integration but no improvement.
Have tried DSS on same data using its recommended settings. The result does not show these artefacts. Any ideas?
Yeah does look like hot pixels. How did you create your bad pixel map exactly? Also, it might be nice to see like 10 frames, 10 darks, 10 flats and 10 bias via wetransfer.com I could have a look at the data and see if something is up. You can mail the link to email@example.com
Thanks Vincent. I'll arrange the transfer as requested. I may have been naive in that I simply selected the option to create a BPM in the calibration stage. I'm relatively new to this and I'm sure its user error. I should say I have created other images with the same setup and process in APP and this is the only one so far that showed this issue.
So I'm seeing the same issue indeed. The darks and bias seem ok, bpm as well. Flats can be a point of some issues sometimes, especially if the way they are taken isn't optimal. How do you make them? I see the exposure time is just 0.02 seconds, which is really fast, usually people use a less bright source of light and longer exposure times.
I tried turning the flats off and then the background is suddenly filled with these things. So it seems a weird pattern in the data, I'm now trying to find out if it's indeed within the data. For that, it would be interesting to see what DSS made of it, could you send the result of that to me at firstname.lastname@example.org?
Allright then, upon further testing.. I switched off all calibration frames as playing with the flats didn't make it better. Doing this made the problem go away and I just see a few hot-pixels causing stripes. So this seems to point to an issue with either the bias or darks. Difficult one to diagnose, I might have to get some help from Mabula but he's abroad at the moment so that might take a while (@mabula-admin).
Thank you Callum, for bringing this issue to our attention.
Can one of you give me a link for download of the data so I can study the data? I will then have a look as soon as possible 😉 to see if I can pinpoint the exact cause of your colored stripes.
Apologies Callum for the delay in solving this issue.
Main developer of Astro Pixel Processor and owner of Aries Productions
I am having a similar problem with an ASI071MC Pro camera as you can see in the screenshot of the attached "overstretched" image.
The problem appears to be in the Master Dark file. I have attached screenshots of the stretched master dark as well as a typical dark sub from the stack used to make the master dark. I am happy to send the actual fits files; and any thoughts would be appreciated.
Hi Mabula, Apologies got back late last night. What email address can I use for We Transfer to get the files to you? Thanks Callum
Hi Callum, I would use email@example.com as I'm currently not able to use my computer during a move abroad (again, yes I know.. 😉 ). @Mabula-admin