J-PLUS: galaxy-star-quasar classification for DR3

We present a dedicated automated pipeline to construct spatially resolved emission Hα+ NII maps and to derive the spectral energy distributions (SEDs) in 12 optical filters (five broad and seven narrow and medium) of Hα emission line regions in nearby galaxies (z $<$ 0.0165) observed by the Javalambre Photometric Local Universe Survey (J-PLUS). We used the J0660 filter of $140$ Å width centered at $6600$ Å to trace Hα + NII emission, and r and i broad bands were used to estimate the stellar continuum. We created pure emission line images after the continnum subtraction, where the Hα emission line regions were detected. This method was also applied to integral field unit (IFU) spectroscopic data from PHANGS-MUSE, CALIFA, and MaNGA surveys by building synthetic narrow bands based on J-PLUS filters. The studied sample includes the cross-matched catalog of these IFU surveys with the J-PLUS third data release (DR3), amounting to two PHANGS-MUSE, $78$ CALIFA, and $78$ MaNGA galaxies at z < 0.0165, respectively. We compared the Hα+ NII radial profiles from J-PLUS and the IFU surveys, finding good agreement within the expected uncertainties. We also compared the SEDs from the emission line regions detected in J-PLUS images, reproducing the main spectral features present in the spectroscopic data. Finally, we compared the emission fluxes from the J-PLUS and IFU surveys accounting for scale differences, finding a difference of only 2% with a dispersion of 7% in the measurements. The J-PLUS data provide reliable spatially resolved Hα+ NII emission maps for nearby galaxies. We provide the J-PLUS DR3 catalog for the $158$ galaxies with IFU data, including emission maps, SEDs of star-forming clumps, and radial profiles.

Context. From the approximately 3500 planetary nebulae (PNe) discovered in our Galaxy, only 14 are known to be members of the Galactic halo. Nevertheless, a systematic search for halo PNe has never been performed. Aims. In this study, we present new photometric diagnostic tools to identify compact PNe in the Galactic halo by making use of the novel 12-filter system projects, Javalambre Photometric Local Universe Survey (J-PLUS) and Southern-Photometric Local Universe Survey (S-PLUS). Methods. We reconstructed the Isaac Newton Telescope Photometric Hα Survey of the Northern Galactic Plane diagnostic diagram and propose four new ones using (i) the J-PLUS and S-PLUS synthetic photometry for a grid of photo-ionisation models of halo PNe, (ii) several observed halo PNe, as well as (iii) a number of other emission-line objects that resemble PNe. All colour–colour diagnostic diagrams are validated using two known halo PNe observed by J-PLUS during the scientific verification phase and the first data release (DR1) of S-PLUS and the DR1 of J-PLUS. Results. By applying our criteria to the DR1s (~1190 deg2), we identified one PN candidate. However, optical follow-up spectroscopy proved it to be a H II region belonging to the UGC 5272 galaxy. Here, we also discuss the PN and two H II galaxies recovered by these selection criteria. Finally, the cross-matching with the most updated PNe catalogue (HASH) helped us to highlight the potential of these surveys, since we recover all the known PNe in the observed area. Conclusions. The tools here proposed to identify PNe and separate them from their emission-line contaminants proved to be very efficient thanks to the combination of many colours, even when applied – like in the present work – to an automatic photometric search that is limited to compact PNe.

Context. Stellar parameters are among the most important characteristics in studies of stars which, in traditional methods, are based on atmosphere models. However, time, cost, and brightness limits restrain the efficiency of spectral observations. The Javalambre Photometric Local Universe Survey (J-PLUS) is an observational campaign that aims to obtain photometry in 12 bands. Owing to its characteristics, J-PLUS data have become a valuable resource for studies of stars. Machine learning provides powerful tools for efficiently analyzing large data sets, such as the one from J-PLUS, and enables us to expand the research domain to stellar parameters. Aims. The main goal of this study is to construct a support vector regression (SVR) algorithm to estimate stellar parameters of the stars in the first data release of the J-PLUS observational campaign. Methods. The training data for the parameters regressions are featured with 12-waveband photometry from J-PLUS and are crossidentified with spectrum-based catalogs. These catalogs are from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, the Apache Point Observatory Galactic Evolution Experiment, and the Sloan Extension for Galactic Understanding and Exploration. We then label them with the stellar effective temperature, the surface gravity, and the metallicity. Ten percent of the sample is held out to apply a blind test. We develop a new method, a multi-model approach, in order to fully take into account the uncertainties of both the magnitudes and the stellar parameters. The method utilizes more than 200 models to apply the uncertainty analysis. Results. We present a catalog of 2 493 424 stars with the root mean square error of 160 K in the effective temperature regression, 0.35 in the surface gravity regression, and 0.25 in the metallicity regression. We also discuss the advantages of this multi-model approach and compare it to other machine-learning methods.

Aims. We present the photometric calibration of the twelve optical passbands for the Javalambre Photometric Local Universe Survey (J-PLUS) second data release (DR2), comprising 1088 pointings of two square degrees, and study the systematic impact of metallicity on the stellar locus technique. Methods. The [Fe/H] metallicity from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) for 146 184 high-quality calibration stars, defined with signal-to-noise ratio larger than ten in J-PLUS passbands and larger than three in Gaia parallax, was used to compute the metallicity-dependent stellar locus (ZSL). The initial homogenization of J-PLUS photometry, performed with a unique stellar locus, was refined by including the metallicity effect in colors via the ZSL. Results. The variation of the average metallicity along the Milky Way produces a systematic offset in J-PLUS calibration. This effect is well above 1% for the bluer passbands and amounts 0.07, 0.07, 0.05, 0.03, and 0.02 mag in u, J0378, J0395, J0410, and J0430, respectively. We modeled this effect with the Milky Way location of the J-PLUS pointing, also providing an updated calibration for those observations without LAMOST information. The estimated accuracy in the calibration after including the metallicity effect is at 1% for the bluer J-PLUS passbands and below for the rest. Conclusions. Photometric calibration with the stellar locus technique is prone to significant systematic bias in the Milky Way for passbands bluer than λ = 4500 Å. The calibration method for J-PLUS DR2 reaches 1–2% precision and 1% accuracy for 12 optical filters within an area of 2176 square degrees.

Context.We present a new methodology for the estimation of stellar atmospheric parameters from narrow- and intermediate-band photometry of the Javalambre Photometric Local Universe Survey (J-PLUS), and propose a method for target pre-selection of low-metallicity stars for follow-up spectroscopic studies. Photometric metallicity estimates for stars in the globular cluster M15 are determined using this method.Aims.By development of a neural-network-based photometry pipeline, we aim to produce estimates of effective temperature,Teff, and metallicity, [Fe/H], for a large subset of stars in the J-PLUS footprint.Methods.The Stellar Photometric Index Network Explorer, SPHINX, was developed to produce estimates ofTeffand [Fe/H], after training on a combination of J-PLUS photometric inputs and synthetic magnitudes computed for medium-resolution (R~ 2000) spectra of the Sloan Digital Sky Survey. This methodology was applied to J-PLUS photometry of the globular cluster M15.Results.Effective temperature estimates made with J-PLUS Early Data Release photometry exhibit low scatter, σ(Teff) = 91 K, over the temperature range 4500 <Teff(K) < 8500. For stars from the J-PLUS First Data Release with 4500 <Teff(K) < 6200, 85 ± 3% of stars known to have [Fe/H] < −2.0 are recovered by SPHINX. A mean metallicity of [Fe/H] = − 2.32 ± 0.01, with a residual spread of 0.3 dex, is determined for M15 using J-PLUS photometry of 664 likely cluster members.Conclusions.We confirm the performance of SPHINX within the ranges specified, and verify its utility as a stand-alone tool for photometric estimation of effective temperature and metallicity, and for pre-selection of metal-poor spectroscopic targets.

Context. Ultracool dwarfs (UCDs) comprise the lowest mass members of the stellar population and brown dwarfs, from M7 V to cooler objects with L, T, and Y spectral types. Most of them have been discovered using wide-field imaging surveys, for which the Virtual Observatory (VO) has proven to be of great utility. Aims. We aim to perform a search for UCDs in the entire Javalambre Photometric Local Universe Survey (J-PLUS) second data release (2176 deg2) following a VO methodology. We also explore the ability to reproduce this search with a purely machine learning (ML)-based methodology that relies solely on J-PLUS photometry. Methods. We followed three different approaches based on parallaxes, proper motions, and colours, respectively, using the VOSA tool to estimate the effective temperatures and complement J-PLUS photometry with other catalogues in the optical and infrared. For the ML methodology, we built a two-step method based on principal component analysis and support vector machine algorithms. Results. We identified a total of 7827 new candidate UCDs, which represents an increase of about 135% in the number of UCDs reported in the sky coverage of the J-PLUS second data release. Among the candidate UCDs, we found 122 possible unresolved binary systems, 78 wide multiple systems, and 48 objects with a high Bayesian probability of belonging to a young association. We also identified four objects with strong excess in the filter corresponding to the Ca ii H and K emission lines and four other objects with excess emission in the Hα filter. Follow-up spectroscopic observations of two of them indicate they are normal late-M dwarfs. With the ML approach, we obtained a recall score of 92% and 91% in the 20 × 20 deg2 regions used for testing and blind testing, respectively. Conclusions. We consolidated the proposed search methodology for UCDs, which will be used in deeper and larger upcoming surveys such as J-PAS and Euclid. We concluded that the ML methodology is more efficient in the sense that it allows for a larger number of true negatives to be discarded prior to analysis with VOSA, although it is more photometrically restrictive.

Context. We explore the stellar content of the Javalambre Photometric Local Universe Survey (J-PLUS) Data Release 2 and show its potential for identifying low-metallicity stars using the Stellar Parameters Estimation based on Ensemble Methods (SPEEM) pipeline. Aims. SPEEM is a tool used to provide determinations of atmospheric parameters for stars and separate stellar sources from quasars based on the unique J-PLUS photometric system. The adoption of adequate selection criteria allows for the identification of metal-poor star candidates that are suitable for spectroscopic follow-up investigations. Methods. SPEEM consists of a series of machine-learning models that use a training sample observed by both J-PLUS and the SEGUE spectroscopic survey. The training sample has temperatures, Teff, between 4800 K and 9000 K, values of log g between 1.0 and 4.5, as well as −3.1 < [Fe/H] < +0.5. The performance of the pipeline was tested with a sample of stars observed by the LAMOST survey within the same parameter range. Results. The average differences between the parameters of a sample of stars observed with SEGUE and J-PLUS, obtained with the SEGUE Stellar Parameter Pipeline and SPEEM, respectively, are ΔTeff ~ 41 K, Δlog g ~ 0.11 dex, and Δ[Fe/H] ~ 0.09 dex. We define a sample of 177 stars that have been identified as new candidates with [Fe/H] < −2.5, with 11 of them having been observed with the ISIS spectrograph at the William Herschel Telescope. The spectroscopic analysis confirms that 64% of stars have [Fe/H] < −2.5, including one new star with [Fe/H] < −3.0. Conclusions. Using SPEEM in combination with the J-PLUS filter system has demonstrated their potential in estimating the stellar atmospheric parameters (Teff, log g, and [Fe/H]). The spectroscopic validation of the candidates shows that SPEEM yields a success rate of 64% on the identification of very metal-poor star candidates with [Fe/H] < −2.5.

Context. The Javalambre Photometric Local Universe Survey (J-PLUS) is an observational campaign that aims to obtain photometry in 12 ultraviolet-visible filters (0.3−1 μm) over ∼8500 deg2 of the sky observable from Javalambre (Teruel, Spain). Due to its characteristics and observation strategy, this survey will allow a great number of Solar System small bodies to be analyzed, and with improved spectrophotometric resolution with respect to previous large-area photometric surveys in optical wavelengths. Aims. The main goal of the present work is to present the first catalog of magnitudes and colors of minor bodies of the Solar System compiled using the first data release (DR1) of the J-PLUS observational campaign: the Moving Objects Observed from Javalambre (MOOJa) catalog. Methods. Using the compiled photometric data we obtained very-low-resolution reflectance (photo)spectra of the asteroids. We first used a σ-clipping algorithm in order to remove outliers and clean the data. We then devised a method to select the optimal solar colors in the J-PLUS photometric system. These solar colors were computed using two different approaches: on one hand, we used different spectra of the Sun convolved with the filter transmissions of the J-PLUS system, and on the other, we selected a group of solar-type stars in the J-PLUS DR1 according to their computed stellar parameters. Finally, we used the solar colors to obtain the reflectance spectra of the asteroids. Results. We present photometric data in the J-PLUS filters for a total of 3122 minor bodies (3666 before outlier removal), and we discuss the main issues with the data, as well as some guidelines to solve them.

Aims. We present the photometric calibration of the 12 optical passbands for the Javalambre Photometric Local Universe Survey (J-PLUS) third data release (DR3) comprising 1642 pointings of two square degrees each. Methods. We selected nearly 1.5 million main sequence stars with a signal-to-noise ratio larger than ten in the 12 J-PLUS passbands and available low-resolution (R = 20–80) spectrum from the blue and red photometers (BP/RP) in Gaia DR3. We compared the synthetic photometry from BP/RP spectra with the J-PLUS instrumental magnitudes after correcting for the magnitude and color terms between both systems in order to obtain a homogeneous photometric solution for J-PLUS. To circumvent the current limitations in the absolute calibration of the BP/RP spectra, the absolute color scale was derived using the locus of 109 white dwarfs closer than 100 pc with a negligible interstellar extinction. Finally, the absolute flux scale was anchored to the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) photometry in the r band. Results. The precision of the J-PLUS photometric calibration estimated from duplicated objects observed in adjacent pointings and by comparison with the spectro-photometric standard star GD 153 is ~12 mmag in u, J0378, and J0395, and it is ~7 mmag in J0410, J0430, ɡ, J0515, r, J0660, i, J0861, and z. The estimated accuracy in the calibration along the surveyed area is better than 1% for all the passbands. Conclusions. The Gaia BP/RP spectra provide a high-quality, homogeneous photometric reference in the optical range across the full sky in spite of their current limitations as an absolute reference. The calibration method for J-PLUS DR3 reaches an absolute precision and accuracy of 1% in the 12 optical filters within an area of 3284 square degrees.

Aims. We used the Javalambre Photometric Local Universe Survey (J-PLUS) second data release (DR2) photometry in 12 optical bands over 2176 deg2 to estimate the fraction of white dwarfs with the presence of Ca II H+K absorption along the cooling sequence. Methods. We compared the J-PLUS photometry against metal-free theoretical models to estimate the equivalent width in the J0395 passband of 10 nm centered at 395 nm (EWJ0395), a proxy to detect calcium absorption. A total of 4399 white dwarfs with effective temperatures within 30 000 > Teff > 5500 K and masses of M > 0.45 M⊙ were analyzed. Their EWJ0395 distribution was modeled using two populations, corresponding to polluted and non-polluted systems, to estimate the fraction of calcium white dwarfs (fCa) as a function of Teff. The probability of each individual white dwarf presenting calcium absorption, pCa, was also computed. Results. The comparison of EWJ0395 with both the measured Ca/He abundance and the identification of metal pollution from spectroscopy shows that EWJ0395 correlates with the presence of Ca II H+K absorption. The fraction of calcium white dwarfs changes along the cooling sequence, increasing from fCa ≈ 0 at Teff = 13 500 K to fCa ≈ 0.15 at Teff = 5500 K. This trend reflects the selection function of calcium white dwarfs in the optical. We compare our results with the fractions derived from the 40 pc spectroscopic sample and from Sloan Digital Sky Survey (SDSS) spectra. The trend found in J-PLUS observations is also present in the 40 pc sample; however, SDSS shows a deficit of metal-polluted objects at Teff < 12 000 K. Finally, we found 39 white dwarfs with pCa > 0.99. Twenty of them have spectra presented in previous studies, whereas we obtained follow-up spectroscopic observations for six additional targets. These 26 objects were all confirmed as metal-polluted systems. Conclusions. The J-PLUS optical data provide a robust statistical measurement for the presence of Ca II H+K absorption in white dwarfs. We find a 15 ± 3% increase in the fraction of calcium white dwarfs from Teff = 13 500 K to 5500 K, which reflects their selection function in the optical from the total population of metal-polluted systems.

Aims.We estimated the spectral evolution of white dwarfs with effective temperature using the Javalambre Photometric Local Universe Survey (J-PLUS) second data release (DR2), which provides 12 photometric optical passbands over 2176 deg2.Methods.We analyzed 5926 white dwarfs withr ≤ 19.5 mag in common between a white dwarf catalog defined fromGaiaEDR3 and J-PLUS DR2. We performed a Bayesian analysis by comparing the observed J-PLUS photometry with theoretical models of hydrogen- and helium-dominated atmospheres. We estimated the probability distribution functions for effective temperature (Teff), surface gravity, parallax, and composition; and the probability of having a H-dominated atmosphere (pH) for each source. We applied a prior in parallax, usingGaiaEDR3 measurements as a reference, and derived a self-consistent prior for the atmospheric composition as a function ofTeff.Results.We described the fraction of white dwarfs with a He-dominated atmosphere (fHe) with a linear function of the effective temperature at 5000 < Teff < 30 000 K. We findfHe = 0.24 ± 0.01 atTeff = 10 000 K, a change rate along the cooling sequence of 0.14 ± 0.02 per 10 kK, and a minimum He-dominated fraction of 0.08 ± 0.02 at the high-temperature end. We tested the obtainedpHby comparison with spectroscopic classifications, finding that it is reliable. We estimated the mass distribution for the 351 sources with distanced < 100 pc, massM > 0.45M⊙, andTeff > 6000 K. The result for H-dominated white dwarfs agrees with previous studies, with a dominantM = 0.59M⊙peak and the presence of an excess atM ∼ 0.8M⊙. This high-mass excess is absent in the He-dominated distribution, which presents a single peak.Conclusions.The J-PLUS optical data provide a reliable statistical classification of white dwarfs into H- and He-dominated atmospheres. We find a 21 ± 3% increase in the fraction of He-dominated white dwarfs fromTeff = 20 000 K toTeff = 5000 K.

The Javalambre Photometric Local Universe Survey (J-PLUS) is an observational campaign that aims to obtain photometry in 12 ultraviolet-visible filters (0.3–1 μm) of ∼8 500 deg2 of the sky observable from Javalambre (Teruel, Spain). Due to its characteristics and strategy of observation, this survey will let us analyze a great number of Solar System small bodies, with improved spectrophotometric resolution with respect to previous large-area photometric surveys in optical wavelengths.The main goal of this work is to present here the first catalog of magnitudes and colors of minor bodies of the Solar System compiled using the first data release (DR1) of the J-PLUS observational campaign: the Moving Objects Observed from Javalambre (MOOJa) catalog.Using the compiled photometric data we obtained very-low-resolution reflectance (photospectra) spectra of the asteroids. We first used a σ-clipping algorithm in order to remove outliers and clean the data. We then devised a method to select the optimal solar colors in the J-PLUS photometric system. These solar colors were computed using two different approaches: on one hand, we used different spectra of the Sun, convolved with the filter transmissions of the J-PLUS system, and on the other, we selected a group of solar-type stars in the J-PLUS DR1, according to their computed stellar parameters. Finally, we used the solar colors to obtain the reflectance spectra of the asteroids.We present photometric data in the J-PLUS filters for a total of 3 122 minor bodies (3 666 before outlier removal), and we discuss the main issues of the data, as well as some guidelines to solve them.

Context. As a consequence of internal and external dynamical processes, Galactic globular clusters (GCs) have properties that vary radially. Wide-field observations covering the entire projected area of GCs out to their tidal radii (rtidal) can therefore give crucial information on these important relics of the Milky Way formation era. Aims. The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide field-of-view (2 deg2) images in 12 narrow, intermediate and broad-band filters optimized for stellar photometry. Here we have applied J-PLUS data for the first time for the study of Galactic GCs using science verification data obtained for the very metal-poor ([Fe/H] ≈−2.3) GC M 15 located at ~10 kpc from the Sun. Previous studies based on spectroscopy found evidence of multiple stellar populations (MPs) through their different abundances of C, N, O, and Na. Our J-PLUS data provide low-resolution spectral energy distributions covering the near-UV to the near-IR, allowing us to instead search for MPs based on pseudo-spectral fitting diagnostics. Methods. We have built and discussed the stellar radial density profile (RDP) and surface brightness profiles (SBPs) reaching up to rtidal. Since J-PLUS FoV is larger than M 15’s rtidal, the field contamination can be properly taken into account. We also demonstrated the power of J-PLUS unique filter system by showing colour-magnitude diagrams (CMDs) using different filter combinations and for different cluster regions. Results. J-PLUS photometric quality and depth are good enough to reach the upper end of M 15’s main-sequence. CMDs based on the colours (u − z) and (J0378 − J0861) are found to be particularly useful to search for splits in the sequences formed by the upper red giant branch (RGB) and asymptotic giant branch (AGB) stars. We interpret these split sequences as evidence for the presence of MPs. Furthermore, we show that the (u − z) × (J0378 − g) colour–colour diagram allows us to distinguish clearly between field and M 15 stars, which is important to minimize the sample contamination. Conclusions. The J-PLUS filter combinations (u − z) and (J0378 − J0861), which are sensitive to metal abundances, are able to distinguish different sequences in the upper RGB and AGB regions of the CMD of M 15, showing the feasibility of identifying MPs without the need of spectroscopy. This demonstrates that the J-PLUS survey will have sufficient spatial coverage and spectral resolution to perform a large statistical study of GCs through multi-band photometry in the coming years.

Context. With its 12 optical filters, the Javalambre-Photometric Local Universe Survey (J-PLUS) provides an unprecedented multicolor view of the local Universe. The third data release (DR3) covers 3192 deg2 and contains 47.4 million objects. However, the classification algorithms currently implemented in the J-PLUS pipeline are deterministic and based solely on the morphology of the sources. Aims. Our goal is to classify the sources identified in the J-PLUS DR3 images as stars, quasi-stellar objects (QSOs), or galaxies. For this task, we present BANNJOS, a machine learning pipeline that utilizes Bayesian neural networks to provide the full probability distribution function (PDF) of the classification. Methods. BANNJOS has been trained on photometric, astrometric, and morphological data from J-PLUS DR3, Gaia DR3, and CatWISE2020, using over 1.2 million objects with spectroscopic classification from SDSS DR18, LAMOST DR9, the DESI Early Data Release, and Gaia DR3. Results were validated on a test set of about 1.4 × 105 objects and cross-checked against theoretical model predictions. Results. BANNJOS outperforms all previous classifiers in terms of accuracy, precision, and completeness across the entire magnitude range. It delivers over 95% accuracy for objects brighter than r = 21.5 mag and ~ 90% accuracy for those up to r = 22 mag, where J-PLUS completeness is ≲ 25%. BANNJOS is also the first object classifier to provide the full PDF of the classification, enabling precise object selection for high purity or completeness, and for identifying objects with complex features, such as active galactic nuclei with resolved host galaxies. Conclusions. BANNJOS effectively classified J-PLUS sources into around 20 million galaxies, one million QSOs, and 26 million stars, with full PDFs for each, which allow for later refinement of the sample. The upcoming J-PAS survey, with its 56 color bands, will further enhance BANNJOS’s ability to detail the nature of each source.

Aims. We present the photometric calibration of the 12 optical passbands observed by the Javalambre Photometric Local Universe Survey (J-PLUS). Methods. The proposed calibration method has four steps: (i) definition of a high-quality set of calibration stars using Gaia information and available 3D dust maps; (ii) anchoring of the J-PLUS gri passbands to the Pan-STARRS photometric solution, accounting for the variation in the calibration with the position of the sources on the CCD; (iii) homogenization of the photometry in the other nine J-PLUS filters using the dust de-reddened instrumental stellar locus in (𝒳 − r) versus (g − i) colours, where 𝒳 is the filter to calibrate. The zero point variation along the CCD in these filters was estimated with the distance to the stellar locus. Finally, (iv) the absolute colour calibration was obtained with the white dwarf locus. We performed a joint Bayesian modelling of 11 J-PLUS colour–colour diagrams using the theoretical white dwarf locus as reference. This provides the needed offsets to transform instrumental magnitudes to calibrated magnitudes outside the atmosphere. Results. The uncertainty of the J-PLUS photometric calibration, estimated from duplicated objects observed in adjacent pointings and accounting for the absolute colour and flux calibration errors, are ∼19 mmag in u, J0378, and J0395; ∼11 mmag in J0410 and J0430; and ∼8 mmag in g, J0515, r, J0660, i, J0861, and z. Conclusions. We present an optimized calibration method for the large-area multi-filter J-PLUS project, reaching 1–2% accuracy within an area of 1022 square degrees without the need for long observing calibration campaigns or constant atmospheric monitoring. The proposed method will be adapted for the photometric calibration of J-PAS, that will observe several thousand square degrees with 56 narrow optical filters.