Catalog Columns

Source Context

The default dataset is a CosmoHub export from catalog 353, table euclid_fs2_mock_dr_v1_1_phz. CosmoHub is PIC’s Hadoop-backed web platform for exploring and exporting large cosmological datasets. The Euclid Consortium identifies catalog 353 as the Euclid Flagship galaxy mock, and describes the release as a synthetic galaxy catalog containing billions of galaxies with hundreds of modeled physical, photometric, and halo properties.

The public catalog page is:

https://cosmohub.pic.es/catalogs/353

The column table below documents the subset selected by the project SQL query. Names in local_name are the parquet names after SQL aliases are applied. Names in source_or_expression are the original CosmoHub columns or SQL expressions.

This project intentionally exports three complementary classes of photometric quantities:

• continuum-only observed fluxes,

• rest-frame absolute fluxes at 10 parsec,

• fully forward-modeled observed fluxes including emission lines, attenuation, Milky Way extinction, and survey-like noise realizations.

The export also includes latent COSMOS template identifiers (sed_cosmos_1 and sed_cosmos_2), which makes it possible to construct approximate pseudo-ground-truth SEDs for benchmarking differentiable SED pipelines such as DSPS.

SED Reconstruction Context

The Euclid Flagship mock does not directly provide high-resolution galaxy spectra or tabulated wavelength-by-wavelength SEDs in the exported CosmoHub table. However, the catalog contains several latent variables describing the underlying synthetic SED generation process.

The most important columns are:

• sed_cosmos_1

• sed_cosmos_2

• frac_cosmos_1 and frac_cosmos_2

• ebv_cosmos_1

• ebv_cosmos_2

• ext_curve_cosmos_1

• ext_curve_cosmos_2

These columns identify the COSMOS/Ilbert template components and associated dust attenuation parameters used internally by the Flagship photometric model.

This allows the project to reconstruct approximate template-level SEDs by:

1. loading the corresponding COSMOS templates,

2. applying the catalog attenuation parameters,

3. combining the two components with normalized catalog fractions,

4. normalizing the rest-frame proxy SED to Euclid *_abs fluxes,

5. comparing rest-frame shape against DSPS and observed-frame photometry against catalog forward-model outputs.

The reconstructed SEDs should be interpreted as pseudo-ground-truth template reconstructions rather than exact intrinsic physical spectra.

Photometry Semantics

The catalog includes several related photometric representations.

Observed Continuum Fluxes

Columns such as:

• lsst_u

• lsst_g

• lsst_r

• lsst_i

• lsst_z

• lsst_y

• euclid_vis

• euclid_nisp_y

• euclid_nisp_j

• euclid_nisp_h

represent observed-frame continuum flux densities including internal attenuation.

These are the simplest fluxes and exclude explicit emission-line forward modeling and Milky Way extinction.

Rest-Frame Absolute Fluxes

Columns ending in _abs represent rest-frame flux densities normalized at 10 parsec:

• lsst_u_abs through lsst_y_abs

• euclid_vis_abs

• euclid_nisp_y_abs

• euclid_nisp_j_abs

• euclid_nisp_h_abs

These quantities are especially useful for:

• SED normalization,

• pseudo-ground-truth template anchoring,

• rest-frame comparisons,

• intrinsic luminosity diagnostics.

Forward-Modeled Survey Fluxes

Columns ending in:

_el_model3_ext_odonnell_ext

represent the most realistic survey-like observables available in the export.

These include:

• stellar continuum,

• modeled emission lines,

• internal attenuation,

• Milky Way extinction,

• survey noise modeling.

Associated columns ending in:

_error

store the modeled photometric uncertainty, while columns ending in:

_error_realization

store noisy realizations of the observed fluxes.

These columns are the preferred targets for:

• probabilistic inference,

• likelihood evaluation,

• chi-square fitting,

• simulation-to-observation benchmarking,

• differentiable forward-model validation.

Selected Column Metadata

name	source_name	group	dtype	unit	description	notes
ra_gal	ra_gal	coordinates	float	deg	Galaxy right ascension.	ICRS-like sky coordinate used for spatial selection.
dec_gal	dec_gal	coordinates	float	deg	Galaxy declination.	ICRS-like sky coordinate used for spatial selection.
ra_mag_gal	ra_mag_gal	coordinates	float	deg	Right ascension associated with the photometry/magnitude position.
dec_mag_gal	dec_mag_gal	coordinates	float	deg	Declination associated with the photometry/magnitude position.
z_true	true_redshift_halo	redshift	float	dimensionless	True halo redshift, aliased by the download query.	Used only for diagnostics in the default workflow.
z_phz	phz_mode_1	redshift	float	dimensionless	First mode of the photometric-redshift probability distribution.	Diagnostic/legacy photo-z column; active science fits DSPS z_obs from photometry.
z_true_gal	true_redshift_gal	redshift	float	dimensionless	True galaxy redshift.	Preferred truth redshift for galaxy-level DSPS validation.
z_obs_gal	observed_redshift_gal	redshift	float	dimensionless	Observed galaxy redshift including peculiar velocity.
z_deepz	zp	redshift	double	dimensionless	DeepZ mode of the p(z) distribution.
redshift_step	redshift_step	redshift	smallint	index	Redshift step from the Flagship DM lensing healpix maps.
phz_flags	phz_flags	redshift	tinyint	flag	NNPZ photometric-redshift quality flag.	0 means no known issue; 1 means insufficient neighbours for robust photo-z.
phz_median	phz_median	redshift	float	dimensionless	NNPZ median of the photometric-redshift PDF.	Diagnostic-only photo-z estimate; active science config does not use it for z_obs initialization or priors.
phz_min_70	phz_min_70	redshift	float	dimensionless	Lower edge of the NNPZ 70 percent PDF interval.
phz_max_70	phz_max_70	redshift	float	dimensionless	Upper edge of the NNPZ 70 percent PDF interval.
phz_min_90	phz_min_90	redshift	float	dimensionless	Lower edge of the NNPZ 90 percent PDF interval.
phz_max_90	phz_max_90	redshift	float	dimensionless	Upper edge of the NNPZ 90 percent PDF interval.
phz_min_95	phz_min_95	redshift	float	dimensionless	Lower edge of the NNPZ 95 percent PDF interval.
phz_max_95	phz_max_95	redshift	float	dimensionless	Upper edge of the NNPZ 95 percent PDF interval.
phz_mode_1_area	phz_mode_1_area	redshift	float	probability	Total PDF area of the first NNPZ photo-z mode.
phz_mode_2	phz_mode_2	redshift	float	dimensionless	Second mode of the NNPZ photo-z PDF when present.
phz_mode_2_area	phz_mode_2_area	redshift	float	probability	Total PDF area of the second NNPZ photo-z mode.
sed_cosmos_1	sed_cosmos_1	SED latent	int8	index	Primary COSMOS SED template identifier in the COSMOS_MOD.list order.	ID range is 0–30 for the 31 local LePhare COSMOS templates.
sed_cosmos_2	sed_cosmos_2	SED latent	int8	index	Secondary COSMOS SED template identifier in the COSMOS_MOD.list order.	Used for two-component COSMOS proxy SED reconstruction.
frac_cosmos_1	frac_cosmos_1	SED latent	float	fraction	Fractional contribution of COSMOS SED component 1.	Optional in current local parquet. If absent, the configured reconstruction policy is explicit.
frac_cosmos_2	frac_cosmos_2	SED latent	float	fraction	Fractional contribution of COSMOS SED component 2.	Optional in current local parquet. Fractions are normalized internally when their finite sum is positive.
color_kind	color_kind	SED latent	int8	category	HOD-based color class: 0 red sequence, 1 green valley, 2 blue cloud.	Used for grouped COSMOS-vs-DSPS diagnostics.
euclid_vis	euclid_vis	photometry	float	erg s^-1 cm^-2 Hz^-1	Simulated Euclid VIS flux density.	Project config interprets this as Fnu in cgs units.
euclid_nisp_y	euclid_nisp_y	photometry	float	erg s^-1 cm^-2 Hz^-1	Simulated Euclid NISP Y-band flux density.
euclid_nisp_j	euclid_nisp_j	photometry	float	erg s^-1 cm^-2 Hz^-1	Simulated Euclid NISP J-band flux density.
euclid_nisp_h	euclid_nisp_h	photometry	float	erg s^-1 cm^-2 Hz^-1	Simulated Euclid NISP H-band flux density.
euclid_vis_abs	euclid_vis_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame Euclid VIS flux density at 10 parsec.	Optional CosmoHub tooltip column used for pseudo-SED anchoring.
euclid_nisp_y_abs	euclid_nisp_y_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame Euclid NISP Y-band flux density at 10 parsec.	Optional CosmoHub tooltip column used for pseudo-SED anchoring.
euclid_nisp_j_abs	euclid_nisp_j_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame Euclid NISP J-band flux density at 10 parsec.	Optional CosmoHub tooltip column used for pseudo-SED anchoring.
euclid_nisp_h_abs	euclid_nisp_h_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame Euclid NISP H-band flux density at 10 parsec.	Optional CosmoHub tooltip column used for pseudo-SED anchoring.
euclid_vis_el_model3_ext	euclid_vis_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	Euclid VIS flux including emission lines and internal attenuation.	Branch-2 target set B.
euclid_vis_el_model3_ext_odonnell_ext	euclid_vis_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	Euclid VIS flux including emission lines, internal attenuation, and Milky Way extinction.	Branch-2 target set C.
euclid_vis_el_model3_ext_odonnell_ext_error	euclid_vis_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the Euclid VIS Milky-Way-extincted flux.	Used for chi-square in branch-2 target set D.
euclid_vis_el_model3_ext_odonnell_ext_error_realization	euclid_vis_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the Euclid VIS Milky-Way-extincted flux.	Branch-2 target set D.
lsst_u	lsst_u	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST u-band.	Active science fit target.
lsst_u_abs	lsst_u_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST u-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_u_el_model3_ext	lsst_u_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST u flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_u_el_model3_ext_odonnell_ext	lsst_u_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST u flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_u_el_model3_ext_odonnell_ext_error	lsst_u_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST u Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_u_el_model3_ext_odonnell_ext_error_realization	lsst_u_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST u Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
lsst_g	lsst_g	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST g-band.	Active science fit target.
lsst_g_abs	lsst_g_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST g-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_g_el_model3_ext	lsst_g_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST g flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_g_el_model3_ext_odonnell_ext	lsst_g_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST g flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_g_el_model3_ext_odonnell_ext_error	lsst_g_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST g Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_g_el_model3_ext_odonnell_ext_error_realization	lsst_g_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST g Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
lsst_r	lsst_r	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST r-band.	Active science fit target.
lsst_r_abs	lsst_r_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST r-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_r_el_model3_ext	lsst_r_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST r flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_r_el_model3_ext_odonnell_ext	lsst_r_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST r flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_r_el_model3_ext_odonnell_ext_error	lsst_r_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST r Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_r_el_model3_ext_odonnell_ext_error_realization	lsst_r_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST r Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
lsst_i	lsst_i	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST i-band.	Active science fit target.
lsst_i_abs	lsst_i_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST i-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_i_el_model3_ext	lsst_i_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST i flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_i_el_model3_ext_odonnell_ext	lsst_i_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST i flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_i_el_model3_ext_odonnell_ext_error	lsst_i_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST i Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_i_el_model3_ext_odonnell_ext_error_realization	lsst_i_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST i Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
lsst_z	lsst_z	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST z-band.	Active science fit target.
lsst_z_abs	lsst_z_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST z-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_z_el_model3_ext	lsst_z_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST z flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_z_el_model3_ext_odonnell_ext	lsst_z_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST z flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_z_el_model3_ext_odonnell_ext_error	lsst_z_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST z Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_z_el_model3_ext_odonnell_ext_error_realization	lsst_z_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST z Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
lsst_y	lsst_y	photometry	float	erg s^-1 cm^-2 Hz^-1	Observed continuum flux including internal attenuation in LSST y-band.	Active science fit target.
lsst_y_abs	lsst_y_abs	rest-frame photometry	float	erg s^-1 cm^-2 Hz^-1 at 10 pc	Rest-frame flux density at 10 parsec in LSST y-band.	Used for COSMOS proxy SED diagnostics when present.
lsst_y_el_model3_ext	lsst_y_el_model3_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST y flux including continuum, emission lines, and internal attenuation.	Diagnostic only until DSPS emission-line likelihood is implemented.
lsst_y_el_model3_ext_odonnell_ext	lsst_y_el_model3_ext_odonnell_ext	photometry	float	erg s^-1 cm^-2 Hz^-1	LSST y flux including emission lines, internal attenuation, and Milky Way extinction.	Survey-like forward-modeled flux; diagnostic only in the active fit.
lsst_y_el_model3_ext_odonnell_ext_error	lsst_y_el_model3_ext_odonnell_ext_error	photometry	float	erg s^-1 cm^-2 Hz^-1	Flux uncertainty for the LSST y Milky-Way-extincted flux.	Used as per-band likelihood uncertainty in the active 10-band config.
lsst_y_el_model3_ext_odonnell_ext_error_realization	lsst_y_el_model3_ext_odonnell_ext_error_realization	photometry	float	erg s^-1 cm^-2 Hz^-1	Noisy realization of the LSST y Milky-Way-extincted flux.	Use for noisy-observation diagnostics, not as the uncertainty.
log_stellar_mass	log_stellar_mass	physical truth	float	log10(Msun h^-2)	Base-10 logarithm of catalog stellar mass.	Convert to log10(Msun) as log_stellar_mass + 2 log10(h).
log_ml_r01	log_ml_r01	physical truth	float	log10(Msun/Lsun)	Logarithm of stellar-mass-to-luminosity ratio in SDSS 0.1-r band.
abs_mag_r01	abs_mag_r01	rest-frame photometry	float	mag + 5 log10(h)	Absolute magnitude in the SDSS 0.1-r band in h=1 units.
log_luminosity_r01	log_luminosity_r01	rest-frame photometry	float	log10(Lsun h^-2)	Base-10 luminosity in the SDSS 0.1-r band.
abs_mag_uv_unextincted	abs_mag_uv_unextincted	rest-frame photometry	float	mag + 5 log10(h)	Unextincted absolute magnitude in a broad ultraviolet filter near 1800 A.	Useful diagnostic for dust/SFR failures, not a direct DSPS fit target.
metallicity_true	metallicity	physical truth	float	12 + log10(O/H)	Gas-phase oxygen abundance, aliased by the download query.	Reports convert to log10 metallicity proxy with offset -10.61.
log_sfr_true	log_sfr	physical truth	float	log10(Msun yr^-1)	Base-10 logarithm of catalog star-formation rate.
sfr_true	POW(10, log_sfr)	physical truth	double	Msun yr^-1	Linear star-formation rate computed by the download query.
ebv_cosmos_1	ebv_cosmos_1	dust	float	mag	COSMOS E(B-V) component 1.
ebv_cosmos_2	ebv_cosmos_2	dust	float	mag	COSMOS E(B-V) component 2.
ext_curve_cosmos_1	ext_curve_cosmos_1	dust	int8	code	Extinction-curve identifier for dust component 1.
ext_curve_cosmos_2	ext_curve_cosmos_2	dust	int8	code	Extinction-curve identifier for dust component 2.
mw_extinction	mw_extinction	dust	float	mag	Milky Way foreground extinction scalar.
dust_ebv_true	SQL CASE expression	dust	float	mag	Single intrinsic E(B-V) target computed by the download query.	Bulge-fraction weighted when both COSMOS dust components are present.
bulge_fraction	bulge_fraction	morphology	float	fraction	Fraction of galaxy light assigned to the bulge component.
disk_r50	disk_r50	morphology	float	arcsec	Disk half-light radius.
bulge_r50	bulge_r50	morphology	float	arcsec	Bulge half-light radius.
eps1_gal	eps1_gal	morphology	float	dimensionless	Galaxy ellipticity component e1.
eps2_gal	eps2_gal	morphology	float	dimensionless	Galaxy ellipticity component e2.
disk_ellipticity	disk_ellipticity	morphology	float	dimensionless	Disk ellipticity.
bulge_ellipticity	bulge_ellipticity	morphology	float	dimensionless	Bulge ellipticity.
bulge_nsersic	bulge_nsersic	morphology	float	dimensionless	Bulge Sersic index.
disk_nsersic	disk_nsersic	morphology	float	dimensionless	Disk Sersic index.
lm_halo	lm_halo	halo	float	log10(Msun h^-1)	Base-10 logarithm of halo mass.
lmbound_halo	lmbound_halo	halo	float	log10(Msun h^-1)	Base-10 logarithm of bound halo mass.
r_halo	r_halo	halo	float	kpc h^-1	Halo radial distance in the lightcone.
x_halo	x_halo	halo	float	Mpc h^-1	Halo Cartesian x coordinate.
y_halo	y_halo	halo	float	Mpc h^-1	Halo Cartesian y coordinate.
z_halo	z_halo	halo	float	Mpc h^-1	Halo Cartesian z coordinate.
vx_halo	vx_halo	halo	float	km s^-1	Halo peculiar velocity x component.
vy_halo	vy_halo	halo	float	km s^-1	Halo peculiar velocity y component.
vz_halo	vz_halo	halo	float	km s^-1	Halo peculiar velocity z component.
n_sats_halo	n_sats_halo	halo	int32	count	Number of satellite galaxies assigned to the halo.
num_p_halo	num_p_halo	halo	int32	count	Number of simulation particles associated with the halo.
conc_vir_halo	conc_vir_halo	halo	float	dimensionless	Virial concentration of the halo.
rs_halo	rs_halo	halo	float	kpc h^-1	Halo NFW scale radius.
rvir_halo	rvir_halo	halo	float	kpc h^-1	Halo virial radius.

Practical DSPS Usage

The exported dataset supports several complementary DSPS workflows.

Minimal Photometric Inference

Use:

• euclid_vis

• euclid_nisp_y

• euclid_nisp_j

• euclid_nisp_h

for simple observed-frame photometric inference without explicit survey-noise forward modeling.

Pseudo-Ground-Truth SED Reconstruction

Use:

• sed_cosmos_1

• sed_cosmos_2

• ebv_cosmos_1

• ebv_cosmos_2

• ext_curve_cosmos_1

• ext_curve_cosmos_2

• *_abs fluxes

to reconstruct approximate latent template SEDs and compare them against DSPS spectral predictions.

Survey-Level Forward Modeling

Use:

• *_el_model3_ext_odonnell_ext

• *_error

• *_error_realization

for likelihood-based inference, noisy photometric simulations, or differentiable survey forward-model validation.

The *_error columns are flux-density uncertainties in the same units as the catalog fluxes. When a band config declares error_column, the pipeline converts the flux uncertainty into a local AB-magnitude uncertainty,

\[\sigma_m \simeq \frac{2.5}{\ln 10}\frac{\sigma_F}{F},\]

and uses it in the photometric likelihood. This gives high signal-to-noise objects stronger weight and prevents faint noisy points from dominating the fit as if every band had the same fixed sigma_mag. sigma_mag_floor and sigma_mag_ceiling in the config keep the weights numerically stable.

The noisy realization columns are not uncertainties. They are one simulated measurement drawn from the survey-like flux plus noise model. Use them when the experiment should mimic measured survey photometry; use the corresponding *_error columns for the likelihood denominator and chi-square.

The science config wires catalog flux errors for all ten LSST+Euclid bands. The fitted flux columns remain the continuum columns because the current DSPS model has continuum plus dust but not a calibrated nebular-emission likelihood; the *_el_model3_ext* fluxes and noisy realizations are diagnostics.

euclid-dsps --config configs/fs2_phz1_science.yaml fit \
  --limit 32 \
  --batch-size 32 \
  --out outputs/runs/dev_fit_batch_10band

For COSMOS SED validation:

euclid-dsps --config configs/fs2_phz1_science.yaml check \
  --kind cosmos \
  --limit 20 \
  --out outputs/check/cosmos

The continuum-only target set is the default science target because the current DSPS model has continuum plus dust, but not nebular emission lines.

References

• CosmoHub catalog page: https://cosmohub.pic.es/catalogs/353

• Euclid Flagship simulation release: https://www.euclid-ec.org/public/press-releases/euclid-flagship-simulations/

• Euclid Flagship galaxy mock paper: https://www.aanda.org/articles/aa/full_html/2025/05/aa50853-24/aa50853-24.html

• IRSA PHZ tutorial showing phz_mode_1 as the first PHZ PDF mode: https://caltech-ipac.github.io/irsa-tutorials/euclid-intro-phz-catalog/