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Known Issues with GES Release gesiDR5

This page documents the known issues with GES Release gesiDR5 as of 24 Novemeber 2017.

1. GIRAFFE VSINI The distribution of GIRAFFE rotational velocities (VROT from the GIRAFFE pipeline) was found to be anomalous. The rotational velocity could not be reliably estimated down to the level of a few km/sec given the variation in resolution of the instrument, in particular due to the procedure implemented in February 2015 to improve the focussing procedure for GIRAFFE. This change resulted in improved spectral resolutions, particularly in the HR settings used by GES. The outcome of this issue is that no GIRAFFE VROT values were selected for inclusion in the Recommended VSINI column in the RecommendedAstroAnalysis table. Any VSINI values that are reported come from other sources (e.g. UVES, WG13, etc, as documented in the WG15 Report).

2. For those who want a VSINI for science use where a recommended VSINI value is not reported in RecommendedAstroAnalysis, the OACT node vsini values for stars observed with the Giraffe HR15N setup can be retrieved from the OACT node table and may be used in science analyses without obtaining permission from the PIs. The OACT node table values are available in the AstroAnalysis table in the Archive (to access them include a constraint like nodeName = 'OACT' in the WHERE clause of the SELECT statement; see here for more details and examples). The OACT vsini values for HR15N were calculated from an empirical correction for the GIRAFFE HR15N pipeline VROT values provided by R. Jackson and A. Frasca. The correction formula, along with a table of input data and documentation, is available to the GES Consortium on the GES DR5 wiki page (link: here).

3. The known issue with the SNR in GIRAFFE in iDR4 has been fixed for iDR5. The scheme to produce the recommended SNR which appears in the RecommendedAstroAnalysis table is described in the WG15 report. The SNR for each spectrum may be found in the Spectrum table.

4. No recommended ALPHA_FE values (global alpha element to iron ratio) are provided for iDR5. Recommended values for abundances of individual alpha-process elements are provided.

5. The fraction of stars with recommended parameters and abundances may have changed compared to iDR4 due to higher quality thresholds applied by WG15 during the homogenisation (e.g. the application of constraints based on the minimum number of node results available). See the full WG15 report for more information.