Pulsating star ?
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dudrea
The mean star just above the bright one at 3 o'clock seems pulse ! In fact it's reduced in frame 2 (it's the only one) Of course I don't think it's a real pulsating star cause time interval between frame is two short. But I wonder what is the cause of that
Posted
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CTidwell3
If you look really close in frame 1 below that bright one at 3 o'clock, you should see a dark spot. This is a flat field defect artifact.
From wikipedia: Flat-field correction is a technique used to improve quality in digital imaging. The goal is to remove artifacts from 2-D images that are caused by variations in the pixel-to-pixel sensitivity of the detector and/or by distortions in the optical path. It is a standard calibration procedure in everything from pocket digital cameras to giant telescopes.
Defects in the flat field that is generated for this purpose can be spots like the one you see there. It causes more data subtracted than needed, and that is what is causing the dimming. In frame 2, this spot move up and right over the star in question. By frame 3 it has moved back down and to the right, then in frame 4 back to the left, causing the dimming only in frame 2.
An easier to see example of this can be seen here:
http://talk.asteroidzoo.org/#/subjects/AAZ0000t4hPosted
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dudrea
Thank's I Haven't noticed the dark spot... That's explain all of course.
Posted
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MvGulik
Bump ... Ref
@MrBill : Center star pulses? Any ideas?
Turn on inverted view in the classifying page to detect flat fields.
Posted
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MvGulik
@Hightower73
Do you have a link to your flat fields post?
(I could not find it, although I'm pretty sure there is one.)Posted