Based on observations collected at the European Southern Observatory at Paranal, Chile (ESO programmes 64.H-0425, 65.H-0602, 68.C-0652 and 69.C-0448).

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IRAF is distributed by the National Optical Astronomy Observatories which are operated by the Association of Universities for Research in Astronomy, Inc., under cooperative agreement with the National Science Foundation.

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... stars

To increase the efficiency of our program the orientation of the slit was chosen such that at least two stars are observed simultaneously.

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