Context. Transient sky astronomy is entering a new era with the advent of the Space Variable Objects Monitor mission (SVOM), successfully launched on 22 June 2024. The primary goal of SVOM is to monitor the hard X-ray sky searching for gamma-ray bursts (GRBs). On top of its on-board follow-up capabilities, SVOM will be backed by its ground segment composed of several facilities, including the near-infrared (NIR) imager CAGIRE. Mounted on the robotic telescope COLIBRI, it will be a unique instrument capable of performing fast follow-up of GRB afterglows in the J and H bands, ideal for capturing high-redshift (z>6) and/or obscured GRBs. Aims. This paper is aimed at estimating the performances of CAGIRE for GRB NIR afterglow detection based on the characteristics of the detector and the specificities of the COLIBRI telescope. Quickly fading GRB afterglows pose challenges that should be addressed by adapting observing strategies to the capabilities of CAGIRE. Methods. We used an end-to-end image simulator to produce realistic CAGIRE images, taking into account the results from the characterisation of the ALFA detector used by CAGIRE. We implemented a GRB afterglow generator that simulates infrared light curves and spectra based on published observation of distant GRBs (z>6). Results. We retrieved the photometry of nine GRB afterglows in various scenarios covered by CAGIRE. Capturing afterglows as early as one minutes after the burst allows for the identification of a NIR counterpart in the brightest four events. When artificially redshifted even further away, these events remain detectable by CAGIRE up to z=9.6 in the J band and z=13.3 in H band, indicating the pioneering potential of CAGIRE in identifying the most distant GRBs to date.

Context. Multi-purpose InSTRument for Astronomy at Low-resolution (MISTRAL) is the new Faint Object Spectroscopic Camera mounted at the folded Cassegrain focus of the 1.93 m telescope of the Haute-Provence Observatory (OHP). Aims. We describe the design and components of the instrument and give some details about its operation. Methods. We emphasize in particular the various observing modes and the performance of the detector. A short description of the working environment is also provided. Various types of objects, including stars, nebulae, comets, novae, and galaxies, have been observed during various test phases to evaluate the performance of the instrument. Results. The instrument covers the range of 4000-8000 angstrom with the blue setting, or from 6000 to 10 000 angstrom with the red setting, at an average spectral resolution of 700. Its peak efficiency is about 22% at 6000 angstrom. In spectroscopy, a limiting magnitude of r similar to 19.5 can be achieved for a point source in one hour with a signal-to-noise ratio of 3 in the continuum (and better when emission lines are present). In imaging mode, limiting magnitudes of 20-21 can be obtained in 10-20 mn (with average seeing conditions of 2.5 arcsec at the OHP). The instrument is very user-friendly and can be put into operations in less than 15 mn (rapid change-over from the other instrument in use) if required by the science (e.g. for gamma-ray bursts). Some first scientific results are described for various types of objects, and in particular, for the follow-up of gamma-ray bursts. Conclusions. While some further improvements are still under way, in particular, to facilitate the switch from blue to red setting and add more grisms or filters, MISTRAL is ready for the follow-up of transients and other variable objects, in the soon-to-come era of the Space-based multi-band astronomical Variable Objects Monitor satellite and of the Rubin telescope, for instance.

MISTRAL is the new Faint Object Spectroscopic Camera mounted at the folded Cassegrain focus of the 1.93m telescope of Haute-Provence Observatory. We describe the design and components of the instrument and give some details about its operation. We emphasise in particular the various observing modes and the performances of the detector. A short description is also given about the working environment. Various types of objects, including stars, nebulae, comets, novae, galaxies have been observed during various test phases to evaluate the performances of the instrument. The instrument covers the range of 4000 to 8000A with the blue setting, or from 6000 to 10000A with the red setting, at an average spectral resolution of 700. Its peak efficiency is about 22% at 6000A. In spectroscopy, a limiting magnitude of 19.5 can be achieved for a point source in one hour with a signal to noise of 3 in the continuum (and better if emission lines are present). In imaging mode, limiting magnitudes of 20-21 can be obtained in 10-20mn (with average seing conditions of 2.5 arcsec at OHP). The instrument is very users-friendly and can be put into operations in less than 15mn (rapid change-over from the other instrument in use) if required by the science (like for Gamma-Rays Bursts). Some first scientific results are described for various types of objects, and in particular for the follow-up of GRBs. While some further improvements are still under way, in particular to ease the switch from blue to red setting and add more grisms or filters, MISTRAL is ready for the follow-up of transients and other variable objects, in the soon-to-come era of e.g. the SVOM satellite and of the Rubin telescope.

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.

We present our follow-up observations with GRANDMA of transient sources revealed by the Zwicky Transient Facility (ZTF). Over a period of six months, all ZTF triggers were examined in real time by a dedicated science module implemented in the Fink broker, which will be used for the data processing of the Vera C. Rubin Observatory. In this article, we present three selection methods to identify kilonova candidates. Out of more than 35 million candidates, a hundred sources have passed our selection criteria. Six were then followed-up by GRANDMA (by both professional and amateur astronomers). The majority were finally classified either as asteroids or as supernovae events. We mobilized 37 telescopes, bringing together a large sample of images, taken under various conditions and quality. To complement the orphan kilonova candidates (those without associated gamma-ray bursts, which were all), we included three additional supernovae alerts to conduct further observations of during summer 2021. We demonstrate the importance of the amateur astronomer community that contributed images for scientific analyzes of new sources discovered in a magnitude range r'=17-19 mag. We based our rapid kilonova classification on the decay rate of the optical source that should exceed 0.3 mag/day. GRANDMA's follow-up determined the fading rate within 1.5+/-1.2 days post-discovery, without waiting for further observations from ZTF. No confirmed kilonovae were discovered during our observing campaign. This work will be continued in the coming months in the view of preparing for kilonova searches in the next gravitational-wave observing run O4.

COLIBRÍ will be a Franco-Mexican 1.3-m telescope and imager for observing the visible and near infrared counterparts of transient events detected by the future SVOM mission. The imager is divided into two instruments: DDRAGO, with two 4k[Formula: see text][Formula: see text][Formula: see text]4k CCDs observing in [Formula: see text] and [Formula: see text], respectively, and CAGIRE, with one 2k[Formula: see text][Formula: see text][Formula: see text]2k LYNRED or H2RG detector observing in [Formula: see text]. DDRAGO will directly image the telescope focal plane with a field of view (FoV) of 26[Formula: see text][Formula: see text][Formula: see text]26 arcmin. CAGIRE will reimage the focal plane to make a pupil image available for a cold stop and adjust the plate scale to deliver a similar FoV. CAGIRE will not use a conventional collimator-camera configuration but rather an arrangement of lenses that sends the pupil image close to the focal plane after all of the reimaging optics. This allows most of the optics, including the infrared filters, to be at ambient temperature and avoids the complexity of having mechanisms and powered optics within the cryostat (CR). We present here the optical design of the system and a thorough analysis on the expected image quality of the instruments and the telescope.

This paper presents an overview of SPIRou, the new-generation near-infrared spectropolarimeter / precision velocimeter recently installed on the 3.6-m Canada-France-Hawaii Telescope (CFHT). Starting from the two main science goals, namely the quest for planetary systems around nearby M dwarfs and the study of magnetized star / planet formation, we outline the instrument concept that was designed to efficiently address these forefront topics, and detail the in-lab and on-sky instrument performances measured throughout the intensive testing phase that SPIRou was submitted to before passing the final acceptance review in early 2019 and initiating science observations. With a central position among the newly started programmes, the SPIRou Legacy Survey (SLS) Large Programme was allocated 300 CFHT nights until at least mid 2022. We also briefly describe a few of the first results obtained in the various science topics that SPIRou started investigating, focusing in particular on planetary systems of nearby M dwarfs, transiting exoplanets and their atmospheres, magnetic fields of young stars, but also on alternate science goals like the atmospheres of M dwarfs and the Earth's atmosphere. We finally conclude on the essential role that SPIRou and the CFHT can play in coordination with forthcoming major facilities like the JWST, the ELTs, PLATO and ARIEL over the decade.

COLIBRI is one of the two robotic ground follow-up telescopes for the SVOM (Space Variable Object Monitor) mission dedicated to the study of gamma-ray bursts, allowing determination of precise celestial coordinates of the detected bursts. COLIBRI telescope is a two-mirror Ritchey-Chretien telescope whose concave primary and convex secondary mirrors have diameters of 1325mm and 485mm respectively. The mirrors are currently manufactured at LAM (Laboratoire d'Astrophysique de Marseille). In this article, the advancement of the work is presented. We also give a global overview and status of the COLIBRI project.

We present in this article some of the techniques applied at the Instituto de Astronomía of the Universidad Nacional Autónoma de México (IA-UNAM) to the mechanical structural design for astronomical instruments. With this purpose we use two recent projects developed by the Instrumentation Department. The goal of this work is to give guidelines about support structures design for achieving a faster and accurate astronomical instruments design. The main guidelines that lead all the design stages for instrument subsystems are the high-level requirements and the overall specifications. From these, each subsystem needs to get its own requirements, specifications, modes of operation, relative position, tip/tilt angles, and general tolerances. Normally these values are stated in the error budget of the instrument. Nevertheless, the error budget is dynamic, it is changing constantly. Depending on the manufacturing accuracy achieved, the error budget is again distributed. That is why having guidelines for structural design helps to know some of the limits of tolerances in manufacture and assembly. The error budget becomes then a quantified way for the interaction between groups; it is the key for teamwork.

We present an overview of the development of the end-to-end simulations programs developed for COLIBRI (Catching OpticaL and Infrared BRIght), a 1.3m robotic follow-up telescope of the forthcoming SVOM (Space Variable Object Monitor) mission dedicated to the detection and study of gamma-ray bursts (GRBs). The overview contains a description of the Exposure Time Calculator, Image Simulator and photometric redshift code developed in order to assess the performance of COLIBRI. They are open source Python packages and were developed to be easily adaptable to any optical/Near-Infrared imaging telescopes. We present the scientific performances of COLIBRI, which allows detecting about 95% of the current GRB dataset. Based on a sample of 500 simulated GRBs, a new Bayesian photometric redshift code predicts a relative photometric redshift accuracy of about 5% from redshift 3 to 7.

SPIRou is a near-infrared (nIR) spectropolarimeter/velocimeter for the Canada-France-Hawaii Telescope (CFHT) that will focus on two forefront science topics, (i) the quest for habitable Earthlike planets around nearby M stars and (ii) the study of low-mass star/planet formation in the presence of magnetic fields. SPIRou will also efficiently tackle many key programs beyond these two main goals, from weather patterns on brown dwarfs to solar system planet and exoplanet atmospheres. SPIRou will cover a wide spectral domain in a single exposure (0.98–2.44 μm) at a resolving power of 70 K, yielding unpolarized and polarized spectra of low-mass stars with a 15% average throughput at a radial velocity (RV) precision of 1 m s−1. It consists of a Cassegrain unit mounted at the Cassegrain focus of CFHT and featuring an achromatic polarimeter, coupled to a cryogenic spectrograph cooled down at 80 K through a fluoride fiber link. SPIRou is currently integrated at IRAP/OMP and will be mounted at CFHT in 2018 Q1 for a first light scheduled in early 2018. Science operation is predicted to begin in 2018 S2, allowing many fruitful synergies with major ground and space instruments such as the JWST, TESS, ALMA, and later-on PLATO and the ELT.

SPIRou is a new near-infrared echelle spectropolarimeter and high precision radial velocity instrument, implemented at the 3.6m Canada-France Hawaii Telescope (CFHT, Mauna Kea) in early 2018. It aims at detecting and characterizing Earth-like planets around M dwarfs and studying stellar and planetary formation in the presence of stellar magnetic field. The calibration unit, with its radial-velocity reference module, is essential to the short- and long-term precision at the level of 1 m/s. We describe the final calibration unit that has been installed. We give technical results such as thermal background level, lamps flux level, lamps stability, and report some technical issues with their solution.