To evaluate the global solar irradiation flux received at the ground surface for Algeria, an analytical model is implemented by processing satellite images and solving the equation of radiative transfer.This model is derived from that initially worked out by C. Gautier et al. in 1980 using high-resolution Goes images.We get that it is well adapted to the processing of lesser resolution images such as those collected by Meteosat 2 following the B2 format.The data base under study mainly consists of clear-sky B2 Meteosat images recorded every three hours in the visible channel (i.e., [0.4 -1.1 µm]) during the 1986/87 period and representing North Africa and Southern Europe.Hourly and daily global solar irradiation fluxes received at the ground on a horizontal surface have therefore been evaluated by applying the analytical model to the Meteosat images.The obtained results were compared to the hourly ground solar measurements recorded in the radiometric stations of Bouzareah (Algiers) and Oran during the 1986/87 period.Since the deviations between both types of solar data do not exceed 10%, the radiances estimated by modelling are found to be close to the related ground measurements.

The New IRAM KID Arrays 2 (NIKA2) consortium has just finished installing and commissioning a millimetre camera on the IRAM 30 m telescope. It is a dual-band camera operating with three frequency multiplexed kilo-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 150 mK, designed to observe the intensity and polarisation of the sky at 260 and 150 GHz (1.15 and 2 mm). NIKA2 is today an IRAM resident instrument for millimetre astronomy, such as Intra Cluster Medium from intermediate to distant clusters and so for the follow-up of Planck satellite detected clusters, high redshift sources and quasars, early stages of star formation and nearby galaxies emission. We present an overview of the instrument performance as it has been evaluated at the end of the commissioning phase.

Millimeter-wave continuum astronomy is today an indispensable tool for both general Astrophysics studies and Cosmology. General purpose, large field-of-view instruments are needed to map the sky at intermediate angular scales not accessible by the high-resolution interferometers and by the coarse angular resolution space-borne or ground-based surveys. These instruments have to be installed at the focal plane of the largest single-dish telescopes. In this context, we have constructed and deployed a multi-thousands pixels dual-band (150 and 260 GHz, respectively 2mm and 1.15mm wavelengths) camera to image an instantaneous field-of-view of 6.5arc-min and configurable to map the linear polarization at 260GHz. We are providing a detailed description of this instrument, named NIKA2 (New IRAM KID Arrays 2), in particular focusing on the cryogenics, the optics, the focal plane arrays based on Kinetic Inductance Detectors (KID) and the readout electronics. We are presenting the performance measured on the sky during the commissioning runs that took place between October 2015 and April 2017 at the 30-meter IRAM (Institut of Millimetric Radio Astronomy) telescope at Pico Veleta. NIKA2 has been successfully deployed and commissioned, performing in-line with the ambitious expectations. In particular, NIKA2 exhibits FWHM angular resolutions of around 11 and 17.5 arc-seconds at respectively 260 and 150GHz. The NEFD (Noise Equivalent Flux Densities) demonstrated on the maps are, at these two respective frequencies, 33 and 8 mJy*sqrt(s). A first successful science verification run has been achieved in April 2017. The instrument is currently offered to the astronomical community during the coming winter and will remain available for at least the next ten years.

The prototype of the NIKA2 camera, NIKA, is a dual-band instrument operating at the IRAM 30-m telescope, which can observe the sky simultaneously at 150 and 260 GHz. One of the main goals of NIKA (and NIKA2) is to measure the pressure distribution in galaxy clusters at high angular resolution using the thermal Sunyaev-Zel'dovich (tSZ) effect. Such observations have already proved to be an excellent probe of cluster pressure distributions even at intermediate and high redshifts. However, an important fraction of clusters host sub-millimeter and/or radio point sources, which can significantly affect the reconstructed signal. Here we report on <20 arcsec angular resolution observations at 150 and 260 GHz of the cluster MACS J1423.8+2404, which hosts both radio and sub-millimeter point sources. We examine the morphological distribution of the tSZ signal and compare it to other datasets. The NIKA data are combined with Herschel satellite data to study the spectral energy distribution (SED) of the sub-millimeter point source contaminants. We then perform a joint reconstruction of the intracluster medium (ICM) electronic pressure and density by combining NIKA, Planck, XMM-Newton, and Chandra data, focusing on the impact of the radio and sub-millimeter sources on the reconstructed pressureprofile. We find that large-scale pressure distribution is unaffected by the point sources because of the resolved nature of the NIKA observations. The reconstructed pressure in the inner region is slightly higher when the contribution of point sources are removed. We show that it is not possible to set strong constraints on the central pressure distribution without accurately removing these contaminants. The comparison with X-ray only data shows good agreement for the pressure, temperature, and entropy profiles, which all indicate that MACS J1423.8+2404 is a dynamically relaxed cool core system. The present observations illustrate the possibility of measuring these quantities with a relatively small integration time, even at high redshift and without X-ray spectroscopy. This work is part of a pilot study aiming at optimizing tSZ observations with the future NIKA2 camera.

NIKA 2 (New Instrument of Kids Array) is a next generation continuum and polarized instrument successfully installed in October 2015 at the IRAM 30 m telescope on Pico-Veleta (Granada, Spain). NIKA 2 is a high resolution dual-band camera, operating with frequency multiplexed LEKIDs (Lumped Element Kinetic Inductance Detectors) cooled at 100 mK. Dual color images are obtained thanks to the simultaneous readout of a 1020 pixels array at 2 mm and 1140 x 2 pixels arrays at 1.15 mm with a final resolution of 18 and 12 arcsec respectively, and 6.5 arcmin of Field of View (FoV). The two arrays at 1.15 mm allow us to measure the linear polarization of the incoming light. This will place NIKA 2 as an instrument of choice to study the role of magnetic fields in the star formation process. The NIKA experiment, a prototype for NIKA 2 with a reduced number of detectors (about 400 LEKIDs) and FoV (1.8 arcmin), has been successfully operated at the IRAM 30 telescope in several open observational campaigns. The performance of the NIKA 2 polarization setup has been successfully validated with the NIKA prototype.

New IRAM KID array 2 (NIKA2) is a camera dedicated to millimeter-wave astronomy based upon kilopixel arrays of kinetic inductance detectors [1] (KID). The pathfinder instrument, NIKA [2], has already shown state-of-the-art detector performance. NIKA2 builds upon this experience but goes one step further, increasing the total pixel count by a factor \(\sim \)10 while maintaining the same per pixel performance. For the next decade, this camera will be the resident photometric instrument of the Institut de Radio Astronomie Millimetrique (IRAM) 30 m telescopes in Sierra Nevada (Spain). In this paper, we give an overview of the main components of NIKA2 and describe the achieved detector performance. The camera has been permanently installed at the IRAM 30 m telescope in October 2015. It will be made accessible to the scientific community at the end of 2016, after a 1-year commissioning period. When this happens, NIKA2 will become a fundamental tool for astronomers worldwide.

The work presented in this paper is focused on the improvement of the kinetic detectors used on NIKA2 instrument (New IRAM KID array 2). Based on the simulation and low temperature measurements, it aims at showing how the variations of the superconducting metal corrupt the frequency comb of the kinetic Inductance detectors (KID) in the frequency range (between 1 and 3 GHz), i.e., how the superconducting metal inhomogeneity induces the resonance-to-resonance cross-coupling which deteriorates the homogeneity of the resonance quality factor and the frequency resonance separation. Solutions are then proposed to fight against the effect of these metallic variations when designing the KID array.

The thermal Sunyaev-Zeldovich effect (tSZ) is a powerful probe to study clusters of galaxies and is complementary with respect to X-ray, lensing or optical observations. Previous arcmin resolution tSZ observations ({\it e.g.} SPT, ACT and Planck) only enabled detailed studies of the intra-cluster medium morphology for low redshift clusters ($z < 0.2$). Thus, the development of precision cosmology with clusters requires high angular resolution observations to extend the understanding of galaxy cluster towards high redshift. NIKA2 is a wide-field (6.5 arcmin field of view) dual-band camera, operated at $100 {\rm mK}$ and containing $\sim 3300$ KID (Kinetic Inductance Detectors), designed to observe the millimeter sky at 150 and 260 GHz, with an angular resolution of 18 and 12 arcsec respectively. The NIKA2 camera has been installed on the IRAM 30-m telescope (Pico Veleta, Spain) in September 2015. The NIKA2 tSZ observation program will allow us to observe a large sample of clusters (50) at redshift ranging between 0.5 and 1. As a pathfinder for NIKA2, several clusters of galaxies have been observed at the IRAM 30-m telescope with the NIKA prototype to cover the various configurations and observation conditions expected for NIKA2.

NIKA is a dual-band camera operating with 315 frequency multiplexed LEKIDs cooled at 100 mK. NIKA is designed to observe the sky in intensity and polarisation at 150 and 260 GHz from the IRAM 30-m telescope. It is a test-bench for the final NIKA2 camera. The incoming linear polarisation is modulated at four times the mechanical rotation frequency by a warm rotating multi-layer half- wave plate. Then, the signal is analyzed by a wire grid and finally absorbed by the lumped element kinetic inductance detectors (LEKIDs). The small time constant ( < 1 ms ) of the LEKIDs combined with the modulation of the HWP enables the quasi-simultaneous measurement of the three Stokes parameters I , Q , U , representing linear polarisation. In this paper, we present the results of recent observational campaigns demonstrating the good performance of NIKA in detecting polarisation at millimeter wavelength.

The Lumped Element Kinetic Inductance Detectors (LEKID)demonstrated full maturity in the NIKA (New IRAM KID Arrays)instrument. These results allow directly comparing LEKID performance with other competing technologies (TES, doped silicon) in the mm and sub-mm range. A continuing effort is ongoing to improve the microfabrication technologies and concepts in order to satisfy the requirements of new instruments. More precisely, future satellites dedicated to CMB (Cosmic Microwave Background) studies will require the same focal plane technology to cover, at least, the frequency range of 60 to 600 GHz. Aluminium LEKID developed for NIKA have so far demonstrated, under real telescope conditions, performance approaching photon-noise limitation in the band 120-300 GHz. By implementing superconducting bi-layers we recently demonstrated LEKID arrays working in the range 80-120 GHz and with sensitivities approaching the goals for CMB missions. NIKA itself (350 pixels) is followed by a more ambitious project requiring several thousands (3000-5000) pixels. NIKA2 has been installed in October 2015 at the IRAM 30-m telescope. We will describe in detail the technological improvements that allowed a relatively harmless 10-fold up-scaling in pixels count without degrading the initial sensitivity. In particular we will briefly describe a solution to simplify the difficult fabrication step linked to the slot-line propagation mode in coplanar waveguide.

A spectral model based on the ground atmosphere exchanges, modelled on the one hand by the satellite image processing and on the other hand by the absorption and the diffusion of the various atmospheric components. This model was implemented to evaluate the total flow of solar irradiation received on the ground; it was applied to data coming from Algerian sites by using images high resolution. These last are from SEVIRI sensor of the new generation satellite Meteosat (MSG), collected by the satellite in high-resolution visible channel (HRV-channel 12) [0,4 -1, 1μm] over four months (February-May 2012). The total flow of solar irradiation received on a horizontal surface, on the level of terrestrial surface, was then evaluated, on the scale of the hour. The results obtained were then compared with the solar data recorded on the ground in two stations: Dar El Beida and Adrar at the time of the same period of measurements. The coefficient of correlation between the radiances values resulting from modeling and those measured on the ground is 0.82. We show thus that the developed spectral analytical model describes the total flow of irradiation and it can be generalized with other sites, at larger periods.

The thermal Sunyaev-Zel’dovich (tSZ) e ect is expected to provide a low scatter mass proxy for galaxy clusters since it is directly proportional to the cluster thermal energy. The tSZ observations have proven to be a powerful tool for detecting and studying them, but high angular resolution observations are now needed to push their investigation to a higher redshift. In this paper, we report high angular (<20 arcsec) resolution tSZ observations of the high-redshift cluster CL J1226.9+3332 (z = 0:89). It was imaged at 150 and 260 GHz using the NIKA camera at the IRAM 30-m telescope. The 150 GHz map shows that CL J1226.9+3332 is morphologically relaxed on large scales with evidence of a disturbed core, while the 260 GHz channel is used mostly to identify point source contamination. NIKA data are combined with those of Planck and X-ray from Chandra to infer the cluster’s radial pressure, density, temperature, and entropy distributions. The total mass profile of the cluster is derived, and we find M500 = 5:96 +1:02 0:79 10 14 M within the radius R500 = 930 +50 kpc, at a 68% confidence level. (R500 is the radius within which the average density is 500 times the critical density at the cluster’s redshift.) NIKA is the prototype camera of NIKA2, a KIDs (kinetic inductance detectors) based instrument to be installed at the end of 2015. This work is, therefore, part of a pilot study aiming at optimizing tSZ NIKA2 large programs.

R. Adam, A. Adane P. Ade, P. Andre, A. Beelen, B. Belier, A. Benoit, A. Bideaud, N. Billot, N. Boudou, O. Bourrion, M. Calvo, A. Catalano, G. Coiffard, B. Comis, A. D’Addabbo, F.-X. Desert, S. Doyle, J. Goupy, C. Kramer, S. Leclercq, J. F. Macias-Perez, J. Martino, P. Mauskopf, F. Mayet, A. Monfardini, F. Pajot, E. Pascale, L. Perotto, E. Pointecouteau, N. Ponthieu, V. Reveret, L. Rodriguez, F. Ruppin, G. Savini, K. Schuster, A. Sievers, C. Tucker, R. Zylka LPSC, Universite Grenoble-Alpes, CNRS/IN2P3, 53, rue des Martyrs, Grenoble, France Institut de RadioAstronomie Millimetrique (IRAM), Grenoble, France Astronomy Instrumentation Group, University of Cardiff, UK AIM, CEA/IRFU, CNRS/INSU, Uni. Paris Diderot, CEA-Saclay, 91191 Gif-Sur-Yvette, France Institut d’Astrophysique Spatiale (IAS), CNRS and Universite Paris Sud, Orsay, France Institut d’Electronique Fondamentale (IEF), Universite Paris Sud, Orsay, France Institut Neel, CNRS and Universite de Grenoble, France Institut de RadioAstronomie Millimetrique (IRAM), Granada, Spain IPAG, CNRS and Universite de Grenoble, France Universite de Toulouse, UPS-OMP, IRAP, Toulouse, France CNRS, IRAP, 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France UCL, Department of Physics and Astronomy, Gower Street, London WC1E 6BT, UK School of Earth and Space Exploration and Dep. of Physics, Arizona State Uni., Tempe, AZ 85287 Dipartimento di Fisica, Sapienza Universita di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy

Clusters of galaxies provide valuable information on the evolution of the Universe and large scale structures. Recent cluster observations via the thermal Sunyaev-Zel'dovich (tSZ) effect have proven to be a powerful tool to detect and study them. In this context, high resolution tSZ observations ( tens of arcsec) are of particular interest to probe intermediate and high redshift clusters. Observations of the tSZ effect will be carried out with the millimeter dual-band NIKA2 camera, based on Kinetic Inductance Detectors (KIDs) to be installed at the IRAM 30-meter telescope in 2015. To demonstrate the potential of such an instrument, we present tSZ observations with the NIKA camera prototype, consisting of two arrays of 132 and 224 detectors that observe at 140 and 240 GHz with a 18.5 and 12.5 arcsec angular resolution, respectively. The cluster RX J1347.5-1145 was observed simultaneously at 140 and 240 GHz. We used a spectral decorrelation technique to remove the atmospheric noise and obtain a map of the cluster at 140 GHz. The efficiency of this procedure has been characterized through realistic simulations of the observations. The observed 140 GHz map presents a decrement at the cluster position consistent with the tSZ nature of the signal. We used this map to study the pressure distribution of the cluster by fitting a gNFW model to the data. Subtracting this model from the map, we confirm that RX J1347.5-1145 is an ongoing merger, which confirms and complements previous tSZ and X-ray observations. For the first time, we demonstrate the tSZ capability of KID based instruments. The NIKA2 camera with 5000 detectors and a 6.5 arcmin field of view will be well-suited for in-depth studies of the intra cluster medium in intermediate to high redshifts, which enables the characterization of recently detected clusters by the Planck satellite.

The New TRAM KID Array (NIKA) is a dual-band camera operating with frequency multiplexed arrays of Lumped Element Kinetic Inductance Detectors (LEKIDs) cooled to 100 mK. NIKA is designed to observe the intensity and polarisation of the sky at 1.25 and 2.14 mm from the TRAM 30 m telescope. We present the improvements on the control of systematic effects and astrophysical results made during the last observation campaigns between 2012 and 2014.

High resolution observations of the thermal Sunyaev-Zel'dovich (tSZ) effect are necessary to allow the use of clusters of galaxies as a probe for large scale structures at high redshifts. With its high resolution and dual-band capability at millimeter wavelengths, the NIKA camera can play a significant role in this context. NIKA is based on newly developed Kinetic Inductance Detectors (KIDs) and operates at the IRAM 30m telescope, Pico Veleta, Spain. In this paper, we give the status of the NIKA camera, focussing on the KID technology. We then present observations of three galaxy clusters: RX J1347.5-1145 as a demonstrator of the NIKA capabilities and the recent observations of CL J1226.9+3332 (z = 0.89) and MACS J0717.5+3745 (z = 0.55). We also discuss prospects for the final NIKA2 camera, which will have a 6.5 arcminute field of view with about 5000 detectors in two bands at 150 and 260 GHz.

This paper deals with the identification and elimination of ground echoes in radar images using their textural features. The images collected in Setif (Algeria) by a non Doppler radar, are processed. Two kinds of texture-based techniques have been considered, consisting in calculating either the histograms of their sum and difference or the pattern recognition. Energy and local homogeneity are found to be the textural parameters that clearly separate the precipitation and ground echoes. To get only the rainfall echoes, the resulting template is applied to each of the raw radar images and the filtering is improved by removing the residual clutter with pattern recognition. This method allows as to completely removing the ground clutter with minimal alterations of the rain echoes with reduced calculation time. It has the advantages of effectiveness and simplicity. However, when there is overlap of precipitation echoes with the ground echoes, significant small cells may occur. In this case, these cells are restored by interpolating from neighboring pixels with a regularization function. The application of this optimization algorithm of filtered images can effectively reproduce true structure of clouds. The radar images can be processed in real-time because the computation time needed by these techniques is small.

NIKA (New IRAM KID Arrays) is a dual-band imaging instrument installed at the IRAM (Institut de RadioAstronomie Millimetrique) 30-meter telescope at Pico Veleta (Spain). Two distinct Kinetic Inductance Detectors (KID) focal planes allow the camera to simultaneous image a field-of-view of about 2 arc-min in the bands 125 to 175 GHz (150 GHz) and 200 to 280 GHz (240 GHz). The sensitivity and stability achieved during the last commissioning Run in June 2013 allows opening the instrument to general observers. We report here the latest results, in particular in terms of sensitivity, now comparable to the state-of-the-art Transition Edge Sensors (TES) bolometers, relative and absolute photometry. We describe briefly the next generation NIKA-2 instrument, selected by IRAM to occupy, from 2015, the continuum imager/polarimeter slot at the 30-m telescope.

The New IRAM KID Array (NIKA) instrument is a dual-band imaging camera operating with Kinetic Inductance Detectors (KID) cooled at 100 mK. NIKA is designed to observe the sky at wavelengths of 1.25 and 2.14 mm from the IRAM 30 m telescope at Pico Veleta with an estimated resolution of 13 arcsec and 18 arcsec, respectively. This work presents the performance of the NIKA camera prior to its opening to the astrophysical community as an IRAM common-user facility in early 2014. NIKA is a test bench for the final NIKA2 instrument to be installed at the end of 2015. The last NIKA observation campaigns on November 2012 and June 2013 have been used to evaluate this performance and to improve the control of systematic effects. We discuss here the dynamical tuning of the readout electronics to optimize the KID working point with respect to background changes and the new technique of atmospheric absorption correction. These modifications significantly improve the overall linearity, sensitivity, and absolute calibration performance of NIKA. This is proved on observations of point-like sources for which we obtain a best sensitivity (averaged over all valid detectors) of 40 and 14 mJy.s^1/2 for optimal weather conditions for the 1.25 and 2.14 mm arrays, respectively. NIKA observations of well known extended sources (DR21 complex and the Horsehead nebula) are presented. This performance makes the NIKA camera a competitive astrophysical instrument.

The study presented in this article, aims at ameliorating the photonic detection for the NIKA (New IRAM KID Array) camera. It mainly consists in simulating this array of superconducting resonators, also called Hilbert KID (Kinetic Inductance Detector), using the Sonnet software, understanding the nature of the cross-talk between these resonators and optimizing the design of this kind of superconductor array. Such a study highlights the effect of the ground plane on the resonance characteristics of the Hilbert-KID array. It also allows getting the best distance between neighboring resonators, which makes the cross-talk negligible. Thanks to this study, an improved configuration of our KID array is found, where the cross-talk is significantly reduced. This result is obtained by optimizing the shape of the ground plane that separates the resonators from each other.