# 20.12.1 rvs_mean_spectrum

This is the RVS mean sampled spectrum table. The spectra are in the rest frame, they are normalised and their wavelength grid ranges from 846 to 870 nm in steps of 0.01 nm (2401 elements).

See Section 6.4.9 for a description on how the mean spectra are obtained, and Seabroke et al. (2022) for a description of the spectra validation.

Note this table is not available through the main archive TAP interface, but via the Massive Data service, indexed by the VO Datalink protocol, described in Chapter 18. For example this can be actioned in the archive user interface by querying the main source catalogue gaia_source and selecting has_rvs = 't'.

The following columns are available in table format only if the ‘RAW’ option is selected in the Datalink pop-up window. If the ‘INDIVIDUAL’ or ‘COMBINED’ options are chosen, all columns other than flux and flux_error are provided in the header of the xml file, while wavelength, flux and flux_error columns are provided in table format.

Columns description:

A unique single numerical identifier of the source obtained from gaia_source (for a detailed description see gaia_source.source_id).

All Gaia data processed by the Data Processing and Analysis Consortium comes tagged with a solution identifier. This is a numeric field attached to each table row that can be used to unequivocally identify the version of all the subsystems that were used in the generation of the data as well as the input data used. It is mainly for internal DPAC use but is included in the published data releases to enable end users to examine the provenance of processed data products. To decode a given solution ID visit https://gaia.esac.esa.int/decoder/solnDecoder.jsp

Barycentric Right Ascension $\alpha $ of the object in ICRS at reference epoch ref_epoch from the gaia_source table.

Barycentric Declination $\delta $ of the object in ICRS at reference epoch ref_epoch from the gaia_source table.

The mean normalized spectrum flux.

The mean flux per wavelength bin is:

$$\mathrm{\U0001d68f\U0001d695\U0001d69e\U0001d6a1}[\U0001d692]=\frac{{\sum}_{j=0}^{n}{f}_{j}[i]}{n}$$ |

where $n$ is the number of flux values ${f}_{j}[i]$ contributing to the wavelength bin $i$, and $j$ is the $j$th CCD spectrum being combined out of a total of $n$ in the wavelength bin $i$.

In general, $n$ corresponds to combined_ccds, but it may be smaller, especially in the bins at the edges of the wavelength range, which are often not sampled by all the CCD spectra shifted to the rest frame.

The uncertainty on the mean normalised flux is:

$$\mathrm{\U0001d68f\U0001d695\U0001d69e\U0001d6a1}\mathrm{\_}\mathrm{\U0001d68e\U0001d69b\U0001d69b\U0001d698\U0001d69b}[\U0001d692]=\frac{{\sigma}_{{f}_{n}}[i]}{\sqrt{n}}$$ |

where ${\sigma}_{{f}_{n}}[i]$ is the standard deviation of all the flux values contributing to the wavelength bin $i$:

$${\sigma}_{{f}_{n}}[i]=\sqrt{\frac{1}{n}\sum _{j=0}^{n}{({f}_{j}[i]-\mathrm{\U0001d68f\U0001d695\U0001d69e\U0001d6a1}[\U0001d692])}^{2}}$$ |

where ${f}_{j}[i]$ is the flux the $j$th CCD spectrum being combined out of a total of $n$ in the wavelength bin $i$.

In general, $n$ corresponds to combined_ccds, but it may be smaller, especially in the bins at the edges of the wavelength range, which are often not sampled by all the CCD spectra. This results in typically larger flux_error at the edges of the combined spectrum.

This reports the number of transits used to compute the mean RVS spectrum.

This number reports the total number of spectra that have been combined (over the combined_transits), taking into account that for any combined transit 1, 2 or 3 spectra can be valid and therefore combined.

This field contains the information on how many deblended spectra have been used to produce this mean RVS spectrum: it is the number of CCD spectra that have been deblended.

The number of non-blended spectra is obtained from: combined_ccds$\mathrm{-}$deblended_ccds