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davidwhogg / OWL

Hogg's messing with Kepler pixels
MIT License
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Why are raw counts so large? #1

Closed davidwhogg closed 10 years ago

davidwhogg commented 10 years ago

Is there a big DC offset being added to the counts? In this star (KIC 3335426) all the pixel values (raw) are around 4e5, but the noise demonstrates that there are truly FAR MORE COUNTS hitting the bright pixels. This can't be a sky level, because then the fainter pixels would be less noisy relative to the brighter pixels. Etc. I guess this is all in the data handbook?

dfm commented 10 years ago

Take a look at page 23 of the Kepler Archive manual. I only vaguely understand all the words there.

mrtommyb commented 10 years ago

Is the difference between e-/s and e- per integration?

davidwhogg commented 10 years ago

No it is a DC offset issue; something about "To restore the values contained in this column to the Analog to Digital Units read off the photometer, subtract the appropriate “fixed offset”, LC or SC (keywords LCFXDOFF and SCFXDOFF), and add the mean black level (keyword MEANBLCK) times the number of readouts (keyword NREADOUT). Then, each count represents one Analog to Digital Unit."

davidwhogg commented 10 years ago

this is all cool but no longer a necessary-to-solve issue; closing