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Fig. 1


Sample high-contrast H-band images from the SPOTS pilot survey taken on VLT NaCo. a) LOCI ADI image of Alhena at linear stretch of ± 7 × 10-7 times the primary star’s peak flux. The image is centered on the A-type primary star (marked with a plus sign and the label A). The area within 0.̋55 of the primary is displayed with a software attenuation of a factor of 1 / 1000 in order to render the resolved G-type secondary star (marked B) visible. Despite the presence of the secondary, the ADI processing effectively removes the primary’s PSF, revealing two faint point sources nearby. Our follow-up observations identify these sources as background stars (marked bg). If they had been comoving companions sharing the host system’s age, their H-band brightness would have corresponded to masses of 29 MJup and 45 MJup in the COND evolutionary models by Baraffe et al. (2003). The field of view read out from the detector was reduced for this observation to allow for faster readout times. b) The S/N map corresponding to image a), produced by cutting the image into concentric annuli and dividing their pixel values by their standard deviation, displayed at a linear stretch of [−5,5 ] σ. Since the secondary star is much fainter than the primary, it does not disturb the well-behaved residual speckle noise pattern. c) LOCI ADI image of EM Cha at a linear stretch of ± 2.2 × 10-5 times the unresolved binary’s peak flux. The location of the unresolved target binary is marked by a plus sign and the label AB. A known background star is visible (marked bg). Its brightness corresponds to a 7 MJup planet at the system age. d) The S/N map corresponding to image c), demonstrating well-behaved residual noise.

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