VizieR Online Data Catalog: Red giants abundance analysis in open clusters (Reddy+, 2019)

Selection of red giants for subsequent spectroscopic observations was made by identifying stars having common proper motions at the putative red giant clump in the cluster colour-magnitude diagram (CMD). The CMDs were created from the available BV and Gaia DR2 photometric magnitudes.

High-resolution and high signal-to-noise (S/N) ratio optical spectra of 18 giant stars in six OCs, namely Stock 2 (3 giants), NGC 2168 (3 giants), NGC 6475 (3 giants), NGC 6991 (4 giants), and NGC 7762 (3 giants) were observed in 2016 September, October, and November with the Robert G. Tull coude cross-dispersed Echelle spectrograph (Tull et al. 1995PASP..107..251T) at the 2.7-m Harlan J. Smith Telescope of the McDonald Observatory. On all occasions we employed the camera with a 2048x2048 24μm pixel CCD detector and 52.67 grooves/mm Echelle grating with exposures centred at 5060Å in order 69. We secured two to four exposures of cluster giants in our target list (Table 1) with each exposure limited to 20-30min to minimize the influence of cosmic rays and to acquire a global S/N of above 100.

(10 data files).