Hi,
I have an image of a small nebula captured with a QHY5iii715C camera (one of a few hundred light images). I processed these through sirilic using default image process settings (lights, darks, biases, flats) except that I added a step to subtract biases from flats (which is not selected by default). During registration, too few stars are identified using default star finding settings and it fails to stack. So I’ve been playing around with the Dynamic PSF settings to try to find parameters that will identify the stars and have noticed some odd things. There are about 17 clear stars in the image; default settings find 4 stars; by reducing the detection threshold to 0.3 and relaxing the PSF checks, I can find 10 stars without appreciable noise, but there are about 6 or 7 stars that I’m unable to get Siril to detect, regardless of how low I set the threshold. One of them is quite odd in that it’s a saturated star and is detected with the default settings, but simply checking the “Relax PSF checks” button makes it not find that star. If I draw a box around them and click “Pick Star” from the right-click menu, it’s able to find these stars but not using Dynamic PSF.
Here’s a link to my file – this is the reference image after preprocessing steps are complete: WeTransfer - Send Large Files & Share Photos Online - Up to 2GB Free
Default PSF settings:
Relax PSF checks:
Reduced threshold finds additional stars:
Reducing threshold further doesn’t find the rest of the stars:
Because I have so few stars in the field of view, it’s important to be able to detect the majority of them so images can be selected for stacking, and it seems like these stars are good enough quality to be detected so I’m confused at the behavior. Maybe this is a bug or the settings can be tuned to find these stars? It’s just odd to me that as I reduce the detection threshold, random pixels are being chosen as stars instead of these real stars which are much more obvious to the eye. Any help or ideas would be appreciated.
Thanks,
Andrew