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The boundary layer is the main dilution factor of gas and aerosol sources but high uncertainties remain on its variability, in particular in southeastern France. Atmospheric dynamics that take place there are complex due to the presence of the sea in the west and the south and by hills in the north and the east. This study is based on a field campaign performed in this area from November 7th, 2019 to January 27th, 2020. Four sites were selected : an urban site equipped with a CIMEL CE376 lidar in the city center of Marseille, two suburban sites (Nîmes and Marignane) equipped with a radiosounding facility and a Vaisala CL31 ceilometer respectively, and a rural site (Observatoire de Haute-Provence – OHP) equipped with radioundings and a CIMEL CE376 lidar, unfortunately encountering many issues during that period. Wind measurements are available for each site. The boundary layer height was retrieved with both the Richardson method and the wavelet transform one. Due to the complexity of aerosol layers encountered above Marseille, the boundary layer height temporal variability is investigated through 2 typical meteorological situations encountered in Marseille, e.g. sea/land breezes and Mistral (regional-northwestward-colder wind blowing over southeastern France from Rhône valley). To better trace the origin of the air masses, the depolarisation ratio from lidar is used. Comparisons between the four sites contribute to describe the spatial variability of the boundary layer height in south-eastern France.

International audience; The temporal evolution of the carbonate system and air-sea CO 2 fluxes are investigated for the first time in the Bay of Marseille (BoM-North Western Mediterranean Sea), a coastal system affected by anthropogenic forcing from the Marseille metropolis. This study presents a two-year time-series (between 2016 and 2018) of fortnightly measurements of A T , C T, pH and derived seawater carbonate parameters at the SOLEMIO station. On this land-ocean boundary area, no linear relationship between A T and salinity in surface water is observed due to sporadic intrusions of freshwater coming from the Rhone River. On an annual scale, the BoM acts as a sink of atmospheric CO 2. This result is consistent with previous studies in the Mediterranean Sea. Mean daily air-sea CO 2 fluxes range between −0.8 mmol C.m −2 .d −1 and-2.2 mmol C.m −2 .d −1 during the study period, depending on the atmospheric CO 2 sampling site used for the estimates. This study shows that the pCO 2 in the surface water is predominantly driven by temperature changes, even if partially counterbalanced by biological activity. Therefore, temperature is the main contributor to the air-sea CO 2 exchange variability. Mean daily Net Ecosystem Production (NEP) estimates from C T budget shows an ecosystem in which autotrophic processes are associated with a sink of CO 2. Despite some negative NEP values, the observed air-sea CO 2 fluxes in the BoM are negative, suggesting that thermodynamic processes are the predominant drivers for these fluxes.

The installation and operation of a telescope in Antarctica represent particular challenges, in particular the requirement to operate at extremely cold temperatures, to cope with rapid temperature fluctuations and to prevent frosting. Heating of electronic subsystems is a necessity, but solutions must be found to avoid the turbulence induced by temperature fluctuations on the optical paths. ASTEP 400 is a 40cm Newton telescope installed at the Concordia station, Dome C since 2010 for photometric observations of fields of stars and their exoplanets. While the telescope is designed to spread star light on several pixels to maximize photometric stability, we show that it is nonetheless sensitive to the extreme variations of the seeing at the ground level (between about 0′′.1 and 5′′) and to temperature fluctuations between –30°C and –80 °C. We analyze both day-time and night-time observations and obtain the magnitude of the seeing caused by the mirrors, dome and camera. The most important effect arises from the heating of the primary mirror which gives rise to a mirror seeing of 0′′.23 K–1. We propose solutions to mitigate these effects. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The Concordia Base in Dome C, Antarctica, is an extremely promising site for photometric astronomy due to the 3-month long night during the Antarctic winter, favorable weather conditions, and low scintillation. The ASTEP project (Antarctic Search for Transiting ExoPlanets) is a pilot project which seeks to identify transiting planets and understand the limits of visible photometry from this site. ASTEP 400 is an optical 40cm telescope with a field of view of 1° × 1°. The expected photometric sensitivity is 1E-3, per hour for at least 1,000 stars. The optical design guarantees high homogeneity of the PSF sizes in the field of view. The use of carbon fibers in the telescope structure guarantees high stability. The focal optics and the detectors are enclosed in a thermally regulated box which withstands extremely low temperatures. The telescope designed to run at -80°C (-110°F) was set up at Dome C during the southern summer 2009-2010. It began its nightly observations in March 2010. © 2010 SPIE.

The ASTEP (Antarctica Search for Transiting ExoPlanets) program was originally aimed at probing the quality of the Dome C, Antarctica for the discovery and characterization of exoplanets by photometry. In the first year of operation of the 40 cm ASTEP 400 telescope (austral winter 2010), we targeted the known transiting planet WASP-19b in order to try to detect its secondary transits in the visible. This is made possible by the excellent sub-millimagnitude precision of the binned data. The WASP-19 system was observed during 24 nights in May 2010. The photometric variability level due to starspots is about 1.8% (peak-to-peak), in line with the SuperWASP data from 2007 (1.4%) and larger than in 2008 (0.07%). We find a rotation period of WASP-19 of 10.7 +/- 0.5 days, in agreement with the SuperWASP determination of 10.5 +/- 0.2 days. Theoretical models show that this can only be explained if tidal dissipation in the star is weak, i.e. the tidal dissipation factor Q'star > 3.10^7. Separately, we find evidence for a secondary eclipse of depth 390 +/- 190 ppm with a 2.0 sigma significance, a phase consistent with a circular orbit and a 3% false positive probability. Given the wavelength range of the observations (420 to 950 nm), the secondary transit depth translates into a day side brightness temperature of 2690(-220/+150) K, in line with measurements in the z' and K bands. The day side emission observed in the visible could be due either to thermal emission of an extremely hot day side with very little redistribution of heat to the night side, or to direct reflection of stellar light with a maximum geometrical albedo Ag=0.27 +/- 0.13. We also report a low-frequency oscillation well in phase at the planet orbital period, but with a lower-limit amplitude that could not be attributed to the planet phase alone, and possibly contaminated with residual lightcurve trends., Accepted for publication in Astronomy and Astrophysics, 13 pages, 13 figures

DDOTI will be a wide-field robotic imager consisting of six 28-cm telescopes with prime focus CCDs mounted on a common equatorial mount. Each telescope will have a field of view of 12 square degrees, will have 2 arcsec pixels, and will reach a 10-sigma limiting magnitude in 60 seconds of r = 18.7 in dark time and r = 18.0 in bright time. The set of six will provide an instantaneous field of view of about 72 square degrees. DDOTI uses commercial components almost entirely. The first DDOTI will be installed at the Observatorio Astron\'omico Nacional in Sierra San Pedro Mart\'ir, Baja California, M\'exico in early 2017. The main science goals of DDOTI are the localization of the optical transients associated with GRBs detected by the GBM instrument on the Fermi satellite and with gravitational-wave transients. DDOTI will also be used for studies of AGN and YSO variability and to determine the occurrence of hot Jupiters. The principal advantage of DDOTI compared to other similar projects is cost: a single DDOTI installation costs only about US$500,000. This makes it possible to contemplate a global network of DDOTI installations. Such geographic diversity would give earlier access and a higher localization rate. We are actively exploring this option., Comment: To appear in the proceedings of SPIE conference 9910 "Observatory Operations: Strategies, Processes, and Systems VI". 12 pages

A well-adapted spectrograph based on an integral field unity adopting an imager slicing concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. Bearing in mind the verification of the optical performances associated with the development of a complete simulation of instrument, a prototyping for the SNAP application is undergoing at Marseille (France) between LAM(INSU) and CPPM/IPNL(IN2P3).

The installation and operation of a telescope in Antarctica represent particular challenges, in particular the requirement to operate at extremely cold temperatures, to cope with rapid temperature fluctuations and to prevent frosting. Heating of electronic subsystems is a necessity, but solutions must be found to avoid the turbulence induced by temperature fluctua- tions on the optical paths. ASTEP 400 is a 40 cm Newton telescope installed at the Concordia station, Dome C since 2010 for photometric observations of fields of stars and their exoplanets. While the telescope is designed to spread star light on several pixels to maximize photometric stability, we show that it is nonetheless sensitive to the extreme variations of the seeing at the ground level (between about 0.1 and 5 arcsec) and to temperature fluctuations between --30 degrees C and --80 degrees C. We analyze both day-time and night-time observations and obtain the magnitude of the seeing caused by the mirrors, dome and camera. The most important effect arises from the heating of the primary mirror which gives rise to a mirror seeing of 0.23 arcsec K--1 . We propose solutions to mitigate these effects., Appears in Astronomical Notes / Astronomische Nachrichten, Wiley-VCH Verlag, 2015, pp.1-21

A dedicated optimized spectrograph based on an integral field unit adopting an imager slicing concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. A prototype for the SNAP application is undergoing test at Marseille (France) between LAM (INSU) and CPPM/IPNL(IN2P3) to provide the verification of the optical performances associated with the development of a complete simulation of the instrument. The goal of this demonstrator is to prove the optical and functional requirements of the SNAP spectrograph: diffraction losses, spectrophotometric calibration, image quality and straylight.

A particular flavor of multi-object spectrographs uses pick-off and steering mirrors. These mirrors perform target selection by relaying the optical beams from variable positions in the focal plane to fixed optics in the instrument. Examples of instrument conceptual designs based on this system are presented and illustrated. Particular emphasis is given to the beam steering mirror (BSM) environment which requires the following mechanical motions: translation, rotations and possibly active deformation of the optical surface. A BSM design featuring translation, tip-tilt and a toroidal deformable surface is presented. First results from a prototype development are also presented. A metrology system including wavefront sensing allows to measure and control the position of the optical beam. This system, required for system tests, integration, calibration and operation, is presented. This work is part of the Laboratoire d'Astrophysique de Marseille (LAM) contribution to the beam manipulation work package of the OPTICON smart focal plane.

We report on the science case high level specifications for a wide field spectrograph instrument for an Extremely Large Telescope (ELT) and present possible concepts. Preliminary designs are presented which resort to different instrument concepts: monolithic integral field (IFU), multi-IFU, and a smart tunable filter. This work is part of the activities performed in the work package ‘Instrumentation’ of the ‘ELT Design Study’, a programme supported by the European Community, Framework Programme 6.

A highlight science case for the European ELT is: First light The First Galaxies and the Ionization State of the Early Universe. It aims at understanding the formation and evolution of the first sources of light at the end of the Dark Ages and of the re-ionization of the Universe. The corresponding instrument requirements are: a few tens of integral field units with spatial sampling ∼20mas and individual fields of ∼1′′ over a wide field of view of 5′×5′ or larger. MultiObject Adaptive Optics is required to locally provide significant image quality enhancement. Spectroscopic observations are required in the near IR domain with a spectral resolution of a few 1000. MOMFIS is a preliminary instrument concept designed for OWL around this science case. The instrument concept and preliminary design are presented. Development efforts are estimated, as well as development risks and required R&D activities.

We propose to implement an Integral-Field Unit (IFU) mode in the near-infrared spectrograph NIRSpec of the future James Webb Space Telescope (JWST), instrument under the responsibility of the European Space Agency (ESA). The IFU mode will provide unique additional scientific capabilities, complementary to those of the main multi-object mode of NIRSpec. It would cover a 3"x3" field of view with a 0.075" sampling and make use of the R=3000 spectral configurations of NIRSpec, covering the complete 1.0-5.0 microns range in three shots. First performance simulations yield a limiting AB magnitude of 24 for a point-like source. On the technical side, the IFU is based on the advanced image slicer concept and would include a stack of forty 900 μm thick, slicing mirrors. We are currently conducting a prototyping work funded by ESA, aiming at demonstrating a TRL6 readiness level for this technology (see presentation by F. Laurent). We present the optical design of the IFU, the strategy used during its definition (minimum impact on NIRSpec), as well as the proposed implementation within the NIRSpec instrument. We will stress that, this currently optional mode is a unique opportunity to provide JWST with a powerful integral field mode at marginal costs.

In the frame of an European Space Agency (ESA) contract, a consortium of three European research institutes (Laboratoire d'Astrophysiqu de Marseille, Centre de Recherche Astronomique de Lyon and the University of Durham) and the Cybernetix company have designed, manufactured and tested a prototype of an Integral Field Unit (IFU) for the NIRSpec instrument of the future James Webb Space Telescope (JWST). After a brief presentation of the optical design of this prototype, which is based on the advanced slicer concept, we will focus on the optical tests of this prototype. We will first present the tests peformed at LAM on the individual optical elements prior to their integration in the mechanical structure, as well as the alignment tests conducted as part of the integration procedure. We will then describe the tests and their results in the visible of the complete IFU system both at room temperature (tests performed at CRAL) and at operating temperature (30 K, tests peformed at the University of Durham). Briefly, these tests included: measurements of the characteristics (position, shape, size ...) of the pseudo-slit of the IFU prototype; measurement of the point-spread-function at different locations within its field of view; and measurement of the position, shape and size of the exit pupils. Last, we will conclude on the TRL6 readiness of the advanced image slicer technique and we will provide a glimpse of how wide-spread this technique is becoming both for ground- and space-based applications.