White points in sky background aperture ?

[PieterVuylsteke]

Hi,

While measuring sometimes some pixels become white inside of the background aperture.
In the word document one sees nicely black, and one nicely whitish.

What is the reason/algorithm for that ?

(my measurement are a bit, eum, wobbly, and it seems it is due to background variations, yes my photo's are calibrated)





Kind regards,
Pieter.

[karenacollins]

Hi,

You have the option enabled to mark pixels that are by default ignored by the background calculation routine. To disable that display, go to Image_Display => Preferences => "Mark pixels > 2 sigma from the mean". Marking the pixels is more for debugging purposes and slows down photometry, so the option should normally be disabled.

Karen

On 5/28/2021 6:23 AM, PieterVuylsteke [via AstroImageJ] wrote:

Hi,

While measuring sometimes some pixels become white inside of the background aperture.
In the word document one sees nicely black, and one nicely whitish.

What is the reason/algorithm for that ?

(my measurement are a bit, eum, wobbly, and it seems it is due to background variations, yes my photo's are calibrated)





Kind regards,
Pieter.

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