# 20.2.3 total_galactic_extinction_map

This table provides the Total Galactic Extinction (TGE) map for extinction parameters $A_{0}$ describing the effective total Galactic extinction and related uncertainties at four separate HEALPix levels, namely levels 6 to 9. For further details see Section 11.3.11 of the online documentation.

Columns description:

solution_id : Solution Identifier (long)

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.

healpix_id : HEALPix identification (long)

The unique HEALPix index number for which the total Galactic extinction parameters are estimated. For further details on the HEALPix scheme used by Gaia, see Bastian and Portell (2020).

healpix_level : HEALPix level used (byte)

The HEALPix level of the HEALPix. The Total Galactic Extinction map is provided at HEALPix levels 6 through 9. For further details on the HEALPix scheme used by Gaia, see Bastian and Portell (2020).

a0 : Mean $A_{0}$ extinction parameter (float, Magnitude[mag] )

The median $A_{0}$ of the selected extinction tracers (giants) as estimated by GSP-Phot from BP/RP spectra, apparent $G$ magnitude and parallax (i.e. azero_gspphot in table gaia_source). $A_{0}$ is the extinction parameter in the adopted Fitzpatrick extinction law (Fitzpatrick 1999), taken as the monochromatic extinction at 541.4 nm.

a0_uncertainty : Uncertainty for the mean $A_{0}$ (float, Magnitude[mag] )

The uncertainty of the mean $A_{0}$ for selected extinction tracers in the HEALPix.

a0_min : Minimum $A_{0}$ value used for the HEALPix of interest (float, Magnitude[mag])

Minimum $A_{0}$ value of the selected extinction tracers (giants) used for the HEALPix of interest.

a0_max : Maximum $A_{0}$ value used for the HEALPix of interest (float, Magnitude[mag])

Maximum $A_{0}$ value of the selected extinction tracers (giants) used for the HEALPix of interest.

num_tracers_used : Number of tracers used (int)

The number of extinction tracers (selected giants) used for calculating the extinction parameters for the HEALPix.

optimum_hpx_flag : Flag to indicate whether a given HEALPix level is the optimum (True) or not (False) (boolean)

The Total Galactic Extinction maps are provided at four different HEALPix levels (i.e. 4 different resolutions, levels 6 through 9). This flag indicates whether a given HEALPix level is the optimum level (True), or not (False).

status : Exit status for TGE (short)

Indicates the exit status of TGE.

0: Nominal processing.

1: Insufficient number of tracers, after validation of input for each source (Step 0).

2: Insufficient number of tracers, after ($T_{\rm eff}$, $M_{G}$) selection (Step 1).

3: Insufficient number of tracers, after check on the distance (Step 2).

4: Insufficient number of tracers, after outlier rejection (Step 3).

5: Insufficient number of tracers, after rejection of tracers with large $A_{0}$ errors (Step 4).

99: Unknown error flag.