# 2.1.2 interstellar_medium_params

This is the main table of DIB parameters from DIB-Spec, derived from spectra binned in galactic latitude, longitude and distance.

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 : HEALPix identification (int)

The pixel number determined by a level 5 HEALPix scheme, which is one of the two identifiers of the DIB-Spec bin voxel. Each voxel is defined by a HEALPix number (level 5) made in the equatorial system and the central heliocentric distance (dc).

lc : Central galactic longitude of voxel (float, Angle[deg])

Galactic longitude of the centre of the DIB-Spec voxel.

bc : Central galactic latitude of voxel (float, Angle[deg])

Galactic latitude of the centre of the DIB-Spec voxel.

dc : Central heliocentric distance of voxel (float, Length & Distance[kpc])

Heliocentric distance of the centre of the DIB-Spec voxel. The distance is defined as the inverse of parallax.

n_targets : Number of target stars in a voxel (int)

Number of target stars used in each DIB-Spec voxel to make the stacked interstellar medium (ISM) spectrum.

snr : SNR of the stacked ISM spectrum at 862.0 nm (float)

Signal-to-noise ratio measured in the stacked ISM spectrum in each DIB-Spec voxel between 860.2 and 861.2 nm, defined as the mean value of flux divided by the standard deviation of the flux.

ew8620 : DIB equivalent width at 862.0 nm (float, Length & Distance[nm])

Equivalent width of the DIB at 862.0 nm in each DIB-Spec voxel.

It is defined from a Gaussian model $f(\lambda ,{p}_{0},{p}_{1},{p}_{2})={p}_{0}\times \mathrm{exp}\left(-\frac{{(\lambda -{p}_{1})}^{2}}{2{p}_{2}^{2}}\right)$ where ${p}_{0}$ and ${p}_{2}$ are the depth and width of the DIB profile, ${p}_{1}$ is the central wavelength and $\lambda $ is the wavelength. The latter is the parameter lambda in the interstellar medium spectra table.

ew8620_lower : Lower confidence level (16%) of DIB equivalent width at 862.0 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the equivalent width of the DIB at 862.0 nm in each DIB-Spec voxel.

The confidence interval has been evaluated by numerical integration of the spectra, while the ew8620 has been computed by an analytical solution. This inconsistency between the calculation of the EW and their upper and lower levels implies that sometimes ew8620 $$ ew8620_lower or ew8620 $>$ ew8620_upper, even if the upper and lower values are consistent with each other. We recommend application of the scaling factor of 1.003 to ew8620_lower and ew8620_upper, see Gaia Collaboration, Schultheis, M., et al. (2023b).

ew8620_upper : Upper confidence level (84%) of DIB equivalent width at 862.0 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the equivalent width of the DIB at 864.8 nm in each DIB-Spec voxel.

The confidence interval has been evaluated by numerical integration of the spectra, while the ew8620 has been computed by an analytical solution. This inconsistency between the calculation of the EW and their upper and lower levels implies that sometimes ew8620 $$ ew8620_lower or ew8620 $>$ ew8620_upper, even if the upper and lower values are consistent with each other. We recommend application of the scaling factor of 1.003 to ew8620_lower and ew8620_upper, see Gaia Collaboration, Schultheis, M., et al. (2023b).

flags8620 : Quality flag of DIB parameters at 862.0 nm (int)

Quality flag of the DIB parameters at 862.0 nm in each DIB-Spec voxel. 0 is the best value and 5 is the worst. The exact definition of the quality flags can be found in Gaia Collaboration, Schultheis, M., et al. (2023b).

p08620 : p0 parameter at 862.0 nm (float)

Depth parameter of the DIB at 862 nm in each DIB-Spec voxel, see parameter ew8620 for details.

p08620_lower : Lower confidence level (16%) of p0 parameter at 862.0 nm (float)

Lower confidence level (16%) of the p0 parameter (depth) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p08620_upper : Upper confidence level (84%) of p0 parameter at 862.0 nm (float)

Upper confidence level (84%) of the p0 parameter (depth) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p18620 : p1 parameter at 862.0 nm (float, Length & Distance[nm])

Central wavelength (p1 parameter) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p18620_lower : Lower confidence level (16%) of p1 parameter at 862.0 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the p1 parameter (central wavelength) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p18620_upper : Upper confidence level (84%) of p1 parameter at 862.0 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the p1 parameter (central wavelength) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p28620 : p2 parameter at 862.0 nm (float, Length & Distance[nm])

Width (p2 parameter) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

p28620_lower : Lower confidence level (16%) of p2 parameter at 862.0 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the p2 parameter (width) of the DIB at 862.0nm in each DIB-Spec voxel, see parameter p08620 for details.

p28620_upper : Upper confidence level (84%) of p2 parameter at 862.0 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the p2 parameter (width) of the DIB at 862.0 nm in each DIB-Spec voxel, see parameter p08620 for details.

ew8648 : DIB equivalent width at 864.8 nm (float, Length & Distance[nm])

Equivalent width of the DIB at 864.8 nm in each DIB-Spec voxel.

It is defined from a Lorentzian model $f(\lambda ,{p}_{0},{p}_{1},{p}_{2})=\frac{-({p}_{0}{p}_{2}^{2})}{{(\lambda -{p}_{1})}^{2}+{p}_{2}^{2}}$ where ${p}_{0}$ and ${p}_{2}$ are the depth and width of the DIB profile, ${p}_{1}$ is the central wavelength and $\lambda $ is the wavelength. The latter is the parameter lambda in the interstellar medium spectra table.

ew8648_lower : Lower confidence level (16%) of DIB equivalent width at 864.8 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the equivalent width of the DIB at 864.8 nm in each DIB-Spec voxel.

The confidence interval has been evaluated by numerical integration of the spectra, while the ew8648 has been computed by an analytical solution. This inconsistency between the calculation of the EW and their upper and lower levels implies that sometimes ew8648 $$ ew8648_lower or ew8648 $>$ ew8648_upper, even if the upper and lower values are consistent with each other. We recommend application of the scaling factor of 1.258 to ew8648_lower and ew8648_upper, see Gaia Collaboration, Schultheis, M., et al. (2023b).

ew8648_upper : Upper confidence level (84%) of DIB equivalent width at 864.8 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the equivalent width of the DIB at 864.8 nm in each DIB-Spec voxel.

The confidence interval has been evaluated by numerical integration of the spectra, while the ew8648 has been computed by an analytical solution. This inconsistency between the calculation of the EW and their upper and lower levels implies that sometimes ew8648 $$ ew8648_lower or ew8648 $>$ ew8648_upper, even if the upper and lower values are consistent with each other. We recommend application of the scaling factor of 1.258 to ew8648_lower and ew8648_upper, see Gaia Collaboration, Schultheis, M., et al. (2023b).

flags8648 : Quality flag of DIB parameters at 864.8 nm (int)

Quality flag of the DIB parameters at 864.8 nm in each DIB-Spec voxel. 0 is the best value and 5 is the worst. The exact definition of the quality flags can be found in Gaia Collaboration, Schultheis, M., et al. (2023b).

p08648 : p0 parameter at 864.8 nm (float)

Depth (p0 parameter) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p08648_lower : Lower confidence level (16%) of p0 parameter at 864.8 nm (float)

Lower confidence level (16%) of the p0 parameter (depth) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p08648_upper : Upper confidence level (84%) of p0 parameter at 864.8 nm (float)

Upper confidence level (84%) of the p0 parameter (depth) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p18648 : p1 parameter at 864.8 nm (float, Length & Distance[nm])

Central wavelength (p1 parameter) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p18648_lower : Lower confidence level (16%) of p1 parameter at 864.8 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the p1 parameter (central wavelength) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p18648_upper : Upper confidence level (84%) of p1 parameter at 864.8 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the p1 parameter (central wavelength) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p28648 : p2 parameter at 864.8 nm (float, Length & Distance[nm])

Width (p2 parameter) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p28648_lower : Lower confidence level (16%) of p2 parameter at 864.8 nm (float, Length & Distance[nm])

Lower confidence level (16%) of the p2 parameter (width) of the DIB at 864.8 nm in each DIB-Spec voxel, see parameter ew8648 for details.

p28648_upper : Upper confidence level (84%) of p2 parameter at 864.8 nm (float, Length & Distance[nm])

Upper confidence level (84%) of the p2 parameter (width) of the DIB at 864.8 nm of the DIB-Spec bin, see parameter ew8648 for details.

dibcont_a0 : Slope a0 of the global continuum fit of the full stacked spectrum (float)

The coefficient ${a}_{0}$ (slope) of the global fit to the continuum of the stacked spectrum. The continuum is defined as ${a}_{0}\lambda +{a}_{1}$ where $\lambda $ is the wavelength given in parameter lambda in the interstellar_medium_spectra table.

dibcont_a0_lower : Lower confidence level (16%) of the slope a0 of the global continuum fit (float)

Lower confidence level (16%) of the dibcont_a0 parameter in each DIB-Spec voxel, see parameter dibcont_a0 for details.

dibcont_a0_upper : Upper confidence level (84%) of the slope a0 of the global continuum fit (float)

Upper confidence level (84%) of the dibcont_a0 parameter in each DIB-Spec voxel, see parameter dibcont_a0 for details.

dibcont_a1 : Intercept a1 of the global continuum fit of the full stacked spectrum (float)

The coefficient ${a}_{1}$ (intercept) of the global fit to the continuum of the stacked spectrum, see parameter dibcont_a0 for details.