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Mapping of the PSF to large radii » History » Version 9

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Emmanuel Bertin, 11/13/2013 08:37 AM


Mapping of the PSF to large radii

We stack star images with SNRs>100 (20 in the u-band) in each channel using reduced images DECam_00180620-25, DECam_00180721-32, and normalizing all exposures to the flux in a ring with diameter 6"<⌀<9". The central 5" are affected by saturation so we merge the stacked star images with the PSFEx model obtained from the concatenation of DECam central CCDs (#28 and #35); basically all pixels at radius <3" are replaced with the PSFEx model while the outer pixels are from the stacked star images, scaled to match the PSFEx model in the ring with diameter 6"<⌀<9". The result is PSF images with a 0.263" pixel scale, normalized to 1 inside a disk with diameter ⌀=6", and with a dynamic range that exceeds 13 magnitudes (~100dB)

channel u g r i z Y
PSF image (N is up, E is left) Stacked PSF model in the u band Stacked PSF model in the g band Stacked PSF model in the r band Stacked PSF model in the i band Stacked PSF model in the z band Stacked PSF model in the Y band
PSF isophotes [mag.arcsec⁻²]
Seeing 0.99" 0.92" 0.83" 0.75" 0.77" 0.77"
Mag offset from ⌀=60" to ⌀=6" 0.0061 0.0049 0.0041 0.0040 0.0116 0.0516