# 20.12.2 xp_summary

This tables contains auxiliary information about the mean BP/RP spectrum of a given source. It should be used in order to refine queries on spectra and build dedicated samples before interrogating the DataLink protocol to download the results of those queries.

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.

bp_n_relevant_bases : Number of bases that are relevant for the representation of this mean BP spectrum (short)

Although all bases defined in the set of bases associated with this mean BP spectrum have been used for the source update process, only the coefficients of the first bp_n_relevant_bases bases are significant.

The criterion adopted to estimate the number of relevant basis functions is based on the standard deviation of the coefficients, normalised to their corresponding square root of variance. All coefficients are divided by the square root of variances, and the standard deviation of the last n values is computed, where n is increasing from 2 onwards. The resulting standard deviation for the last n coefficients is then compared with the (idealised) theoretical expectation of 1, plus a configurable threshold times the standard error on the standard deviation. The largest index for which the standard deviation exceeds this limit is taken as the highest coefficient in the truncated representation and the number of relevant bases.

bp_relative_shrinking : Measure of the relative shrinking of the coefficient vector when truncation is applied for the mean BP spectrum (float)

This parameter is defined as the ratio between the lengths of the truncated and full BP spectrum defined by the array of coefficients to be applied to the basis functions.

Number of measurements contributing to solution.

Number of measurements that have been rejected.

bp_standard_deviation : Standard deviation for the BP spectrum representation (float, Flux[e${}^{-}$ pix${}^{-1}$ s${}^{-1}$])

Standard deviation of the solution.

${\chi}^{2}$ of the solution.

Number of BP epoch spectra that contributed to the mean spectrum (some samples from these spectra may still have been rejected).

Number of BP epoch spectra (considering only spectra that contributed to the mean spectrum) matched to this source that were marked as contaminated.

Number of BP epoch spectra (considering only spectra that contributed to the mean spectrum) matched to this source that were marked as blended.

rp_n_relevant_bases : Number of bases that are relevant for the representation of this mean RP spectrum (short)

Although all bases defined in the set of bases associated with this mean RP spectrum have been used for the source update process, only the coefficients of the first rp_n_relevant_bases bases are significant.

The criterion adopted to estimate the number of relevant basis functions is based on the standard deviation of the coefficients, normalised to their corresponding square root of variance. All coefficients are divided by the square root of variances, and the standard deviation of the last n values is computed, where n is increasing from 2 onwards. The resulting standard deviation for the last n coefficients is then compared with the (idealised) theoretical expectation of 1, plus a configurable threshold times the standard error on the standard deviation. The largest index for which the standard deviation exceeds this limit is taken as the highest coefficient in the truncated representation and the number of relevant bases.

rp_relative_shrinking : Measure of the relative shrinking of the coefficient vector when truncation is applied for the mean RP spectrum (float)

This parameter is defined as the ratio between the lengths of the truncated and full RP spectrum defined by the array of coefficients to be applied to the basis functions.

Number of measurements contributing to solution.

Number of measurements that have been rejected.

rp_standard_deviation : Standard deviation for the RP spectrum representation (float, Flux[e${}^{-}$ pix${}^{-1}$ s${}^{-1}$])

Standard deviation of the solution.

${\chi}^{2}$ of the solution.

Number of RP epoch spectra that contributed to the mean spectrum (some samples from these spectra may still have been rejected).

Number of RP epoch spectra (considering only spectra that contributed to the mean spectrum) matched to this source that were marked as contaminated.

Number of RP epoch spectra (considering only spectra that contributed to the mean spectrum) matched to this source that were marked as blended.