45 research outputs found
Telescope guide and pointing precision at THEMIS
We present the very basic featuresâfrom the observerâs point of viewâof the software pack allowing for driving the telescope, the dome, the preslit at the primary focus and the field rotator between the primary and the secondary focus. The original program was developed by C. Veillet as an adaptation for THEMIS of the program used to drive the âLaser-Luneâ telescope at the Observatoire of the
CËote dâAzur (France). Further adaptations were made by the authors to meet observational and technical needs emerged during operation of the THEMIS telescope. When talking about the way observations at THEMIS are affected by the pointing precisionw e clearly have to distinguish betweento different levels: 1) a short-term effect, affecting
short-term observing actions such as scans on the solar disk and 2) a long-term level affecting the correct tracking of a target. All short-term effects just depend on the precision of the software interface and we discuss here their origin, the way they are controlled, their value and how they affect scanning procedures. All long-term effects depend on precision of the software interface but also
on mechanical and optical alignment accuracy
Absolute calibration and beam reconstruction of MITO (a ground-based instrument in the millimetric region)
An efficient sky data reconstruction derives from a precise characterization
of the observing instrument. Here we describe the reconstruction of
performances of a single-pixel 4-band photometer installed at MITO (Millimeter
and Infrared Testagrigia Observatory) focal plane. The strategy of differential
sky observations at millimeter wavelengths, by scanning the field of view at
constant elevation wobbling the subreflector, induces a good knowledge of beam
profile and beam-throw amplitude, allowing efficient data recovery. The
problems that arise estimating the detectors throughput by drift scanning on
planets are shown. Atmospheric transmission, monitored by skydip technique, is
considered for deriving final responsivities for the 4 channels using planets
as primary calibrators.Comment: 14 pages, 6 fiugres, accepted for pubblication by New Astronomy (25
March
MITO measurements of the Sunyaev-Zeldovich Effect in the Coma cluster of galaxies
We have measured the Sunyaev-Zeldovich effect towards the Coma cluster
(A1656) with the MITO experiment, a 2.6-m telescope equipped with a 4-channel
17 arcminute (FWHM) photometer. Measurements at frequency bands 143+/-15,
214+/-15, 272+/-16 and 353+/-13 GHz, were made during 120 drift scans of Coma.
We describe the observations and data analysis that involved extraction of the
S-Z signal by employing a spatial and spectral de-correlation scheme to remove
a dominant atmospheric component. The deduced values of the thermal S-Z effect
in the first three bands are DT_{0} = -179+/-38,-33+/-81,170+/-35 microKelvin
in the cluster center. The corresponding optical depth, tau=(4.1+/-0.9)
10^{-3}, is consistent (within errors) with both the value from a previous low
frequency S-Z measurement, and the value predicted from the X-ray deduced gas
parameters.Comment: Ap.J.Letters accepted, 4 pages, 2 figure
Calibration and First light of the Diabolo photometer at the Millimetre and Infrared Testa Grigia Observatory
We have designed and built a large-throughput dual channel photometer,
Diabolo. This photometer is dedicated to the observation of millimetre
continuum diffuse sources, and in particular, of the Sunyaev-Zel'dovich effect
and of anisotropies of the 3K background. We describe the optical layout and
filtering system of the instrument, which uses two bolometric detectors for
simultaneous observations in two frequency channels at 1.2 and 2.1 mm. The
bolometers are cooled to a working temperature of 0.1 K provided by a compact
dilution cryostat. The photometric and angular responses of the instrument are
measured in the laboratory. First astronomical light was detected in March 1995
at the focus of the new Millimetre and Infrared Testa Grigia Observatory (MITO)
Telescope. The established sensitivity of the system is of 7 mK_RJ s^1/2$. For
a typical map of at least 10 beams, with one hour of integration per beam, one
can achieve the rms values of y_SZ ~ 7 10^-5 and the 3K background anisotropy
Delta T/T ~ 7 10^-5, in winter conditions. We also report on a novel bolometer
AC readout circuit which allows for the first time total power measurements on
the sky. This technique alleviates (but does not forbid) the use of chopping
with a secondary mirror. This technique and the dilution fridge concept will be
used in future scan--modulated space instrument like the ESA Planck mission
project.Comment: 10 pages, LaTeX, 12 figures, accepted for publication in Astronomy
and Astrophysics Supplement Serie
The GAPS Programme at TNG : LV. Multiple molecular species in the atmosphere of HAT-P-11 b and review of the HAT-P-11 planetary system
Context. The atmospheric characterisation of hot and warm Neptune-size exoplanets is challenging mainly due to their relatively small radius and atmospheric scale height, which reduce the amplitude of atmospheric spectral features. The warm-Neptune HAT-P-11 b is a remarkable target for atmospheric characterisation because of the large brightness of its host star (V = 9.46 mag; H = 7.13 mag).
Aims: The aims of this work are to review the main physical and architectural properties of the HAT-P-11 planetary system, and to probe the presence of eight molecular species in the atmosphere of HAT-P-11 b through near-infrared (NIR) high-resolution transmission spectroscopy.
Methods: We reviewed the physical and architectural properties of the HAT-P-11 planetary system by analysing transits and occultations of HAT-P-11 b from the Kepler data set as well as HIRES at Keck archival radial-velocity data. We modelled the latter with Gaussian-process regression and a combined quasi-periodic and squared-exponential kernel to account for stellar variations on both (short-term) rotation and (long-term) activity-cycle timescales. In order to probe the atmospheric composition of HAT-P-11 b, we observed four transits of this target with the NIR GIANO-B at TNG spectrograph and cross-correlated the data with template atmospheric transmission spectra.
Results: We find that the long-period radial-velocity signal previously attributed to the HAT-P-11 c planet (P ~ 9.3 yr; Mp sin i ~ 1.6 MJ; e ~ 0.6) is more likely due to the stellar magnetic activity cycle. Nonetheless, the HIPPARCOS-Gaia difference in the proper-motion anomaly suggests that an outer-bound companion might still exist. For HAT-P-11 b, we measure a radius of Rp = 0.4466 ± 0.0059 RJ, a mass of Mp = 0.0787 ± 0.0048 MJ, a bulk density of Ïp = 1.172 ± 0.085 g cmâ3, and an orbital eccentricity of e = 0.2577â0.0025+0.0033. These values are compatible with those from the literature. Probing its atmosphere, we detect the presence of two molecular species, H2O and NH3, with a S/N of 5.1 and 5.3, and a significance of 3.4 Ï and 5.0 Ï, respectively. We also tentatively detect the presence of CO2 and CH4, with a S/N of 3.0 and 4.8, and a significance of 3.2 Ï and 2.6 Ï, respectively.
Conclusions: We revisit the HAT-P-11 planetary system, confirm the presence of H2O, and report the detection of NH3 in the atmosphere of HAT-P-11 b, also finding hints for the presence of CO2 and CH4 that need to be confirmed by further observations
Reconnecting with nature for sustainability
Calls for humanity to âreconnect to natureâ have grown increasingly louder from both scholars and civil society. Yet, there is relatively little coherence about what reconnecting to nature means, why it should happen and how it can be achieved. We present a conceptual framework to organise existing literature and direct future research on humanânature connections. Five types of connections to nature are identified: material, experiential, cognitive, emotional, and philosophical. These various types have been presented as causes, consequences, or treatments of social and environmental problems. From this conceptual base, we discuss how reconnecting people with nature can function as a treatment for the global environmental crisis. Adopting a socialâecological systems perspective, we draw upon the emerging concept of âleverage pointsââplaces in complex systems to intervene to generate changeâand explore examples of how actions to reconnect people with nature can help transform society towards sustainability
Mortality of neuromyelitis optica spectrum disorder patients in an Argentinean population: a study from the RelevarEM registry
We aimed to evaluate mortality and causes of death among Argentinean neuromyelitis optica spectrum disorder (NMOSD) patients and identify predictors of death. Retrospective study included 158 NMOSD patients and 11 (7%) patients died after 11 years of follow-up for a total exposure time of 53,345 days with an overall incidence density of 2.06âĂâ10.000 patients/day (95% CI 1.75-2.68). Extensive cervical myelitis with respiratory failure (45%) was the most frequent cause of death. Older age (HRâ=â2.05, pâ=â0.002) and higher disability score (HRâ=â2.30, pâ<â0.001) at disease onset were independent predictors of death. We found an 11-year mortality rate of 7% in Argentinean NMOSD patients
Assessing attacks and treatment response rates among adult patients with NMOSD and MOGAD: data from a nationwide registry in Argentina
We aimed to examine treatment interventions implemented in patients experiencing neuromyelitis optica spectrum disorders (NMOSD) attacks (frequency, types, and response). METHODS: Retrospective study. Data on patient demographic, clinical and radiological findings, and administered treatments were collected. Remission status (complete [CR], partial [PR], no remission [NR]), based on changes in the EDSS score was evaluated before treatment, during attack, and at 6âmonths. CR was analyzed with a generalized estimating equations (GEEs) model. RESULTS: A total of 131 patients (120 NMOSD and 11 myelin oligodendrocyte glycoprotein-antibody-associated diseases [MOGAD]), experiencing 262 NMOSD-related attacks and receiving 270 treatments were included. High-dose steroids (81.4%) was the most frequent treatment followed by plasmapheresis (15.5%). CR from attacks was observed in 47% (105/223) of all treated patients. During the first attack, we observed CR:71.2%, PR:16.3% and NR:12.5% after the first course of treatment. For second, third, fourth, and fifth attacks, CR was observed in 31.1%, 10.7%, 27.3%, and 33.3%, respectively. Remission rates were higher for optic neuritis vs. myelitis (pâ<â0.001). Predictor of CR in multivariate GEE analysis was age in both NMOSD (ORâ=â2.27, pâ=â0.002) and MOGAD (ORâ=â1.53, pâ=â0.03). CONCLUSIONS: This study suggests individualization of treatment according to age and attack manifestation. The outcome of attacks was generally poor
The GAPS Programme at TNG. XXVIII. A pair of hot-Neptunes orbiting the young star TOI-942
Context. Young stars and multi-planet systems are two types of primary objects that allow us to study, understand, and constrain planetary formation and evolution theories. Aims: We validate the physical nature of two Neptune-sized planets transiting TOI-942 (TYC 5909-319-1), a previously unacknowledged young star (50-20+30 Myr) observed by the TESS space mission in Sector 5. Methods: Thanks to a comprehensive stellar characterization, TESS light curve modeling and precise radial-velocity measurements, we validated the planetary nature of the TESS candidate and detected an additional transiting planet in the system on a larger orbit. Results: From photometric and spectroscopic observations we performed an exhaustive stellar characterization and derived the main stellar parameters. TOI-942 is a relatively active K2.5V star (log R'HK = -4.17 ± 0.01) with rotation period Prot = 3.39 ± 0.01 days, a projected rotation velocity v sin iâ = 13.8 ± 0.5 km s-1, and a radius of ~0.9 Râ. We found that the inner planet, TOI-942 b, has an orbital period Pb = 4.3263 ± 0.0011 days, a radius Rb = 4.242-0.313+0.376 Râ, and a mass upper limit of 16 Mâ at 1Ï confidence level. The outer planet, TOI-942 c, has an orbital period Pc = 10.1605-0.0053+0.0056 days, a radius Rc = 4.793-0.351+0.410 Râ, and a mass upper limit of 37 Mâ at 1Ï confidence level. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated by the FundaciĂłn Galileo Galilei (FGG) of the Istituto Nazionale di Astrofisica (INAF) at the Observatorio del Roque de los Muchachos (La Palma, Canary Islands, Spain). The authors became aware of a parallel effort on the characterization of TOI-942 by Zhou et al. (2021) in the late stages of the manuscript preparations. The submissions are coordinated, and no analyses or results were shared prior to submission
Long-term safety and efficacy of Eculizumab in Aquaporin-4 IgG-positive NMOSD
Objective
During PREVENT (NCT01892345), eculizumab significantly reduced relapse risk versus placebo in patients with aquaporin-4 immunoglobulin G-positive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD). We report an interim analysis of PREVENT's ongoing open-label extension (OLE; NCT02003144) evaluating eculizumab's long-term safety and efficacy.
Methods
Patients who completed PREVENT could enroll in the OLE to receive eculizumab (maintenance dose = 1,200âmg/2âweeks, after a blinded induction phase). Safety and efficacy data from PREVENT and its OLE (interim data cut, July 31, 2019) were combined for this analysis.
Results
Across PREVENT and the OLE, 137 patients received eculizumab and were monitored for a median (range) of 133.3âweeks (5.1â276.9âweeks), for a combined total of 362.3 patient-years (PY). Treatment-related adverse event (AE) and serious adverse event (SAE) rates were 183.5 in 100 PY and 8.6 in 100 PY, respectively. Serious infection rates were 10.2 in 100 PY in eculizumab-treated patients versus 15.1 in 100 PY in the PREVENT placebo group. No patient developed a meningococcal infection. At 192âweeks (3.7âyears), 94.4% (95% confidence interval [CI], 88.6â97.3) of patients remained adjudicated relapse-free. The adjudicated annualized relapse rate was 0.025 (95% CI = 0.013â0.048) in all eculizumab-treated patients versus 0.350 (95% CI = 0.199â0.616) in the PREVENT placebo group. During the OLE, 37% of patients (44 of 119 patients) stopped or decreased background immunosuppressive therapy use.
Interpretation
This analysis demonstrates that eculizumab's long-term safety profile in NMOSD is consistent with its established profile across other indications. This analysis also demonstrated the sustained ability of long-term eculizumab treatment to reduce relapse risk in patients with AQP4-IgG+ NMOSD. ANN NEUROL 2021;89:1088â109