Modernización del reflector de 76 cm. de la Estación Astronómica Dr. Carlos Ulrico Cesco

Se describen los trabajos realizados para corregir defectos y modernizar el telescopio reflector de 76 cm. a fin de posibilitar el uso de sensores tipo CCD en imagen directa. También se detallan los trabajos proyectados para el futuro con el objeto de optimizar el uso del instrumento.Asociación Argentina de Astronomí

Bright 30 THz Impulsive Solar Bursts

Impulsive 30 THz continuum bursts have been recently observed in solar flares, utilizing small telescopes with a unique and relatively simple optical setup concept. The most intense burst was observed together with a GOES X2 class event on October 27, 2014, also detected at two sub-THz frequencies, RHESSI X-rays and SDO/HMI and EUV. It exhibits strikingly good correlation in time and in space with white light flare emission. It is likely that this association may prove to be very common. All three 30 THz events recently observed exhibited intense fluxes in the range of 104 solar flux units, considerably larger than those measured for the same events at microwave and sub-mm wavelengths. The 30 THz burst emission might be part of the same spectral burst component found at sub-THz frequencies. The 30 THz solar bursts open a promising new window for the study of flares at their originComment: 11 pages, 4 Figures J. Geophys. Res - Space Physics, accepted, May 21, 201

A structured jet explains the extreme GRB 221009A

Long duration gamma-ray bursts (GRBs) are powerful cosmic explosions, signaling the death of massive stars. Among them, GRB 221009A is by far the brightest burst ever observed. Due to its enormous energy ($E_\textrm{iso}\!\approx$10$^{55}$ erg) and proximity ($z\!\approx$0.15), GRB 221009A is an exceptionally rare event that pushes the limits of our theories. We present multi-wavelength observations covering the first three months of its afterglow evolution. The X-ray brightness decays as a power-law with slope $\approx\!t^{-1.66}$, which is not consistent with standard predictions for jetted emission. We attribute this behavior to a shallow energy profile of the relativistic jet. A similar trend is observed in other energetic GRBs, suggesting that the most extreme explosions may be powered by structured jets launched by a common central engine.Comment: Submitted version. 53 pages, 9 figures, 6 table

Estudio del tiempo de vida de los grupos de manchas solares registrados por SOON

Las manchas solares son estructuras que emergen en escalas de tiempos de horas a días y pueden llegar a durar de días a semanas. Debido a la rotación solar, no siempre es posible tener un registro completo del tiempo de vida de los grupos de manchas con observaciones desde Tierra. Esto dificulta obtener los tiempos de vida característicos que son imprescindibles en modelos de transporte de flujo magnético o modelos de dínamo solar. Por ello hacemos uso de la función Kaplan-Meier (K-M) que es una técnica estadística aplicable cuando la muestra a analizar incluye observaciones o mediciones incompletas debido a la naturaleza misma de los datos. En este trabajo presentamos los primeros resultados obtenidos al analizar los datos provistos por los distintos observatorios de la red SOON (Solar Observing Optical Network) que abarca el periodo comprendido de 1982 a 2016.Sunspots are structures that emerge on time scales from hours to days and can last from days to weeks. Due to the solar rotation, it is not always possible to have a complete record of the lifetime of the sunspot groups with observations from Earth. This impedes to correctly characterize the lifetime of sunspots groups, which are essential parameters in magnetic flux transport or solar dynamo models. For this reason we use the Kaplan-Meier function, which is a statistical technique applicable when a portion of the data or observations is not detectable. In this paper we present the first results obtained by analyzing the data provided by the different observatories of SOON (Solar Observing Optical Network) that covers the period from 1982 to 2016.Asociación Argentina de Astronomí