Strange Noise - Help needed

[nrd]

Dear All
i see this noise in my image (appears across the diagonal).
Would request members for advice on what could be the possible source and how can I handle this in Pixinsight.

[Geoff]

Bright out of field star??

[nrd]

geoff
i couldn't understand your question.
my query is about the noise / strands of color diagonally across the image.

[msmythers]

Looking at your image it was a little difficult to make out the problem at first. Once the image is enlarged it was easy to spot.

You might what to check out these postings.
http://pixinsight.com/forum/index.php?topic=9609

http://pixinsight.com/forum/index.php?topic=10104




Mike

[pfile]

that is due to leftover hot pixels after calibration not being rejected during stacking. you can try being more aggressive with sigma high (lowering it).

the "real" cause is lack of dithering; what you're seeing is differential flexure between your guider and imager.

another approach is to use cosmetic correction after calibration to try to eliminate the hot pixels.

rob

[wimvb]

This pattern is quite common in undithered DSLR images, as previous replies already have touched upon. The pattern is caused by pattern noise from the sensor not being removed by the stacking algorithm, in combination with a small displacement between subs. The best way to get rid of it (in future images) is to use dithering in both RA and DEC. It can also occur in guided images, if your guiding isn't spot on. The displacement between subs can be caused by improper balancing of your setup. I have been able to remove the pattern by changing the balance of my scope, but it wasn't very reproducible.
To reduce the pattern in existing images, you can try this:

http://pixinsight.com.ar/en/info/processing-examples/19/crux-southern-cross.html

and this:

http://wimvberlo.blogspot.se/2016/07/noise-reduction-for-dslr-astroimages.html

Hope this helps