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Astron. Astrophys. 361, L9-L12 (2000)

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2. Observations

We observed the HD 100546 star ([FORMULA]=6.7) using the SHARP II+ camera coupled with the adaptative optics system ADONIS, and mounted on the ESO 3.6m telescope at La Silla, Chile. A pre-focal optics coronograph (Beuzit et al. 1997) was used to reject the direct starlight and increase the integration time in each elementary exposure. The mask size we used has a diameter of 0.74". J (1.25 µm) and Ks (2.15 µm) band exposures were obtained on nights 23 and 24 of June, 1999. The seeing was quite variable the first night, but had decreased to a value of [FORMULA] at the time of the J and Ks observations. It was stable at a value around [FORMULA] during the second night. We spent a total observing time of 1550 s in the Ks band and 2600 s in the J band. The Point Spread Function (PSF) was frequently monitored thanks to interlaced observations of two reference stars, HD 97218 and HD 101713. These reference stars were used later in the reduction process to remove the wings of the stellar PSF and for photometric calibration. Observations of empty fields were also performed to estimate and remove the background flux which can be important in the Ks band.

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© European Southern Observatory (ESO) 2000

Online publication: September 5, 2000