Detect Stars Feature in Image Management

rkymtnbiker

Can you tell me about the Detect Stars feature while reviewing images in Image Management? The feature seems to detect the medium sized stars in the image and calculates FWHM based upon those stars. Does this FWHM value give us an estimate of the seeing conditions for that photo if the focus is good? Why doesn't this Detect Stars feature use all of the stars in the photo; especially the larger stars?

w7ay

rkymtnbiker Why doesn't this Detect Stars feature use all of the stars in the photo; especially the larger stars?

Because you cannot estimate the HFD of a saturated star. Most of the saturated star's flux would be in the clipped portion and therefore cannot even be measured. So HFD of a saturated star will make no sense.

Chen

StevenEvan

rkymtnbiker Does this FWHM value give us an estimate of the seeing conditions for that photo if the focus is good?

I can, roughly. At the start of a session I'll take a 3 second image and use Tools>Detect Star. On good nights I see lower values for FWHM. With my setup I expect around 1.8 with great seeing and 2.2 on bad nights (focus peaked using a Bahtinov mask). Everything else being equal.

Steve