arXiv subjects

M. Merino

Publications and source records attributed to M. Merino.

6 recordsLinked to original sources

arXiv2025

A degenerate Takens--Bogdanov bifurcation in a normal form of Lorenz's equations

In this work we consider an unfolding of a normal form of the Lorenz system near a triple-zero singularity. We are interested in the analysis of double-zero bifurcations emerging from that singularity. Their local study provide partial results that are extended by means of numerical continuation methods. Specifically, a curve of heteroclinic connections is detected. It has a degenerate point from which infinitely many homoclinic connections emerge. In this way, we can partially understand the dynamics near the triple-zero singularity.

math.DS↗

arXiv2024

Data-driven sparse modeling of oscillations in plasma space propulsion

An algorithm to obtain data-driven models of oscillatory phenomena in plasma space propulsion systems is presented, based on sparse regression (SINDy) and Pareto front analysis. The algorithm can incorporate physical constraints, use data bootstrapping for additional robustness, and fine-tuning to different metrics. Standard, weak and integral SINDy formulations are discussed and compared. The scheme is benchmarked in the case of breathing-mode oscillations in Hall effect thrusters, using PIC/fluid simulation data. Models of varying complexity are obtained for the average plasma properties, and shown to have a clear physical interpretability and agreement with existing 0D models in the literature. Lastly, the algorithm applied is also shown to enable the identification of physical subdomains with qualitatively different plasma dynamics, providing valuable information for more advanced modeling approaches.

physics.plasm-ph↗

arXiv2011

Status of Telescope Fabra ROA at Montsec: Optical Observations for Space Surveillance & Tracking

The telescope Fabra ROA at Montsec (TFRM) is a 0.5m f/1 refurbished Baker-Nunn Camera (BNC) operated by a collaboration between the Fabra Observatory - Royal Academy of Arts and Sciences of Barcelona and the Spanish Navy Observatory (ROA), and installed at Montsec Astronomical Observatory (Spain). Among other capabilities, its CCD FoV (4.4°x4.4°), the telescope tracking at arbitrary RA and DEC rates, and the CCD shutter commanding at will during the exposure are specially remarkable for Space Surveillance and Tracking (SST) observational programs. On Feb 2011, the TFRM participated, in the CO-VI third run satellite tracking campaign of the ESA SST/Space Surveillance Awareness Preparatory Program (SST/SSA-PP). During this multi-asset 7-day campaign the TFRM conducted systematic observations of artificial satellites which yielded to the determination of 1137 accurate position measurements. Since Feb 2011, the TFRM is observing in remote and fully unattended robotic modes under commissioning status. A summary of the results of the ESA CO-VI SST optical observational campaign and insights of other SST-like observations in process will be presented.

astro-ph.EP↗

arXiv2011

The Fabra-ROA Telescope at Montsec (TFRM): A Fully Robotic Wide-field Telescope for Space Surveillance and Tracking

Since the beginning of the Space Age optical sensors have been one of the main instruments for positioning and tracking known space objects. Nowadays, the unrelenting growth of man-made objects together with the overcrowding of the useful satellite orbits, and the real space debris and NEO hazards, has made necessary to carry out surveys of the space looking for uncatalogued objects. Optical telescopes play a key role in the Space Surveillance and Tracking (SST) as a primary Space Situational Awareness element and, it is known, that the best instrument for this task is a fully robotic wide-field telescope with a minimum aperture of 40cm. The Baker-Nunn Cameras (BNCs) were produced by the Smithsonian Institution during the late 50s as an optical tracking system for artificial satellites. These wide-field telescopes of 50cm of aperture were manufactured by Perkin- Elmer (optics) and Boller & Chivens (mechanics) with the highest quality specifications. The TFRM is a fully robotic refurbished BNC that exploits the excellent mechanical and optical original design to obtain an equatorial telescope with a useful 4.4°x4.4° CCD field of view. TFRM is therefore a European asset very well suited for SST (satellites and space debris) and NEO observations. Moreover, its control system allows tracking of all kinds of orbits, including LEOs.

astro-ph.EP↗

arXiv2009

The Fabra-ROA Baker-Nunn Camera at Observatori Astronòmic del Montsec: a wide-field imaging facility for exoplanet transit detection

A number of Baker-Nunn Camera (BNC) were manufactured by Smithsonian Institution during the 60s as optical tracking systems for artificial satellites with optimal optical and mechanical specifications. One of them was installed at the Real Instituto y Observatorio de la Armada (ROA). We have conducted a profound refurbishment project of the telescope to be installed at Observatori Astronòmic del Montsec (OAdM). As a result, the BNC offers the largest combination of a huge FOV (4.4$°$x4.4$°$) and aperture (leading to a limiting magnitude of V$\sim$20). These specifications, together with their remote and robotic natures, allows this instrument to face an observational program of exoplanets detection by means of transit technique with high signal-to-noise ratio in the appropiate magnitude range.

astro-ph.EP↗

arXiv2005

The Calar Alto lunar occultation program: update and new results

We present an update of the lunar occultation program which is routinely carried out in the near-IR at the Calar Alto Observatory. A total of 350 events were recorded since our last report (Fors et al. 2004). In the course of eight runs we have observed, among others, late-type giants, T-Tauri stars, and infrared sources. Noteworthy was a passage of the Moon close to the galactic center, which produced a large number of events during just a few hours in July 2004. Results include the determinations of the angular diameter of RZ Ari, and the projected separations and brightness ratios for one triple and 13 binary stars, almost all of which representing first time detections. Projected separations range from 0.09arcsec to 0.007arcsec. We provide a quantitative analysis of the performance achieved in our observations in terms of angular resolution and sensitivity, which reach about 0.003arcsec and K~8.5mag, respectively. We also present a statistical discussion of our sample, and in particular of the frequency of detection of binaries among field stars.

astro-ph↗