S. Agayeva, V. Aivazyan, S. Alishov, M. Almualla, C. Andrade, Sarah Antier, J. M. Bai, A. Baransky, S. Basa, P. Bendjoya, Z. Benkhaldoun, S. Beradze, D. Berezin, U. Bhardwaj, M. Blazek, O. Burkhonov, E. Burns, S. Caudill, N. Christensen, F. Colas, A. Coleiro, W. Corradi, M. Coughlin, T. Culino, D. Darson, D. Datashvili, G. de Wasseige, T. Dietrich, F. Dolon, D. Dornic, J. Dubouil, J.-G. Ducoin, P.-A. Duverne, A. Esamdin, A. Fouad, F. Guo, V. Godunova, P. Gokuldass, N. Guessoum, E. Gurbanov, R. Hainich, E. Hasanov, P. Hello, T. Hussenot-Desenonges, R. Inasaridze, A. Iskandar, E.E.O. Ishida, N. Ismailov, T. Jegou du Laz, D.A. Kann, G. Kapanadze, S. Karpov, R.W. Kiendrebeogo, A. Klotz, N. Kochiashvili, A. Kaeouach, J.-P. Kneib, W. Kou, K. Kruiswijk, S. Lombardo, M. Lamoureux, N. Leroy, A. Le Van Su, J. Mao, M. Masek, T. Midavaine, A. Moeller, D. Morris, R. Natsvlishvili, F. Navarete, S. Nissanke, K. Noonan, K. Noysena, N.B. Orange, J. Peloton, M. Pilloix, T. Pradier, M. Prouza, G. Raaijmakers, Y. Rajabov, J.-P. Rivet, Y. Romanyuk, L. Rousselot, F. Ruenger, V. Rupchandani, T. Sadibekova, N. Sasaki, A. Simon, K. Smith, O. Sokoliuk, X. Song, A. Takey, Y. Tillayev, I. Tosta e Melo, D. Turpin, A. de Ugarte Postigo, M. Vardosanidze, X.F. Wang, D. Vernet, Z. Vidadi, J. Zhu, Y. Zhu
GRANDMA is a world-wide collaboration with the primary scientific goal of studying gravitational-wave sources, discovering their electromagnetic counterparts and characterizing their emission. GRANDMA involves astronomers, astrophysicists, gravitational-wave physicists, and theorists. GRANDMA is now a truly global network of telescopes, with (so far) 30 telescopes in both hemispheres. It incorporates a citizen science programme (Kilonova-Catcher) which constitutes an opportunity to spread the interest in time-domain astronomy. The telescope network is an heterogeneous set of already-existing observing facilities that operate coordinated as a single observatory. Within the network there are wide-field imagers that can observe large areas of the sky to search for optical counterparts, narrow-field instruments that do targeted searches within a predefined list of host-galaxy candidates, and larger telescopes that are devoted to characterization and follow-up of the identified counterparts. Here we present an overview of GRANDMA after the third observing run of the LIGO/VIRGO gravitational-wave observatories in 2019 − 2020 and its ongoing preparation for the forthcoming fourth observational campaign (O4). Additionally, we review the potential of GRANDMA for the discovery and follow-up of other types of astronomical transients.
The purpose of this theoretical study carried out under CNES contract is to analyze the feasibility of small space debris detection and classification with an optical sensor on-board micro-satellite. Technical solutions based on active and passive sensors are analyzed and compared. For the most appropriated concept an optimization was made and theoretical performances in terms of number of detection versus class of diameter were calculated. Finally we give some preliminary physical sensor features to illustrate the concept (weight, volume, consumption,…).
An efficient all-fiber 1.53 micrometers high peak power and high repetition rate pulse laser source is presented. The first stage is a ring fiber laser principally including a short length of Er3+ doped fiber pumped by a 980/500 mW compact MOPA, and a short rise time acoustooptic modulator. Another length of a different Er3+ doped fiber pumped by a second MOPA works as an amplifying stage for the emitted pulses. With this optimized source, 30 ns/1 kW triangular pulses at 10 kHz, with a stability better than 0.2% have been obtained. This corresponds to a conversion efficiency of the optical power from the pump to the pulses reaching 30%. These performances make this source very suitable for eyesafe range finding and free space communications. Thanks to its robustness and compactness due to its all-fiber design and to the use of small size pump MOPAs, this source is well-adapted for portable field applications.
AEROSPATIALE, leading a European team, has just conducted a successful study, under ESA contract, to demonstrate the feasibility of a spaceborne Doppler wind lidar instrument meeting the scientific requirements of wind velocity measurements from space with high spatial resolution. A first parametric investigation, based upon the initial set of mission requirements, and supported by dedicated models and detailed trade-off studies, took account of capabilities of most promising signal processing algorithms and calibration/validation constraints: it yielded a large conically scanned instrument deemed technologically risky. A risk analysis was then carried out to propose a less challenging instrument meeting most key mission requirements. The fixed line-of-sight concept with return signal accumulation appeared as most attractive. A second set of requirements agreed upon by scientific users was therefore issued, with relaxed constraints mainly on horizontal resolution, keeping roughly the same level of wind velocity measurement accuracy. A second instrument and subsystem trade-off was then performed to eventually produce an attractive instrument concept based upon a pair of small diameter telescopes each one associated to one scanning mirror rotating stepwise around the telescope axis, which drastically reduces the detection bandwidth. Following the main contract, studies of accommodation on the International Space Station have been performed, confirming the interest of such an instrument for wind measurements from space.
AEROSPATIALE, leading a European team, has just conducted a successful study, under ESA contract, to demonstrate the feasibility of a spaceborne Doppler wind lidar instrument meeting the scientific requirements of wind velocity measurements from space with high spatial resolution. A first parametric investigation, based upon the initial set of mission requirements, and supported by dedicated models and detailed trade-off studies, took account of capabilities of the most promising signal processing algorithms and calibration/validation constrains: it yielded a large conically scanned instrument deemed technologically risky. A risk analysis was then carried out to propose a less challenging instrument meeting most key mission requirements. The fixed line-of-sight concept with return signal accumulation appeared as most attractive. A second set of requirements agreed upon by scientific users was therefore issued, with relaxed constraints mainly on horizontal resolution, keeping roughly the same level of wind velocity measurement accuracy. A second instrument and subsystem trade- off was then performed to eventually produce an attractive instrument concept based upon a pair of small diameter telescopes each one associated to one scanning mirror rotating stepwise around the telescope axis, which drastically reduces the detection bandwidth. Following the main contract, studies of accommodation on the International Space Station have been performed, confirming the interest of such an instrument for wind measurements from space.
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