Aims: We study small-scale brightenings in Ca II 8542 Å line-core images to determine their nature and effect on localized heating and mass transfer in active regions. Methods: High-resolution two-dimensional spectroscopic observations of a solar active region in the near-infrared Ca II 8542 Å line were acquired with the GREGOR Fabry-Pérot

We discuss the status of the calibration programme for CanariCam and related initiatives that aim to provide quality calibration facilities for users of the GTC and other telescopes. We have Visible and IR photometry of >300 stars apt for the calibration of CanariCam giving an initial density of ~ 1 star per 100 square degrees of sky. The

We describe an ongoing effort to validate the estimated atmospheric parameters (Teff, log g, [Fe/H]) obtained from SDSS spectroscopy (R = 2000) and ugriz photometry, which are being employed for both the previous SDSS-I and the ongoing SEGUE surveys. The spectroscopic pipeline makes use of a number of methods for the estimation of each parameter

The question of whether or not solar g-modes can be detected and identified from ground observations is addressed. The limitation imposed by the Earth's atmosphere, the background solar noise spectrum at low frequencies, and a poor theoretical knowledge of these modes are mentioned. Using the best uninterrupted full disk velocity measurements

We compare the rate of kinetic energy injected by stellar winds into the extragalactic H II region NGC 2363 to the luminosity needed to feed the observed temperature fluctuations. The kinetic luminosity associated to the winds is estimated by means of two different evolutionary synthesis codes, one of which takes into account the statistical

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