The currently active neutron star transient and atoll source Aql X-1 (Linares et al., ATEL #2288) has begun the transition from the hard (extreme island) state to the soft (banana) state (Rodriguez et al. ATEL #2299). This transition likely began around 2009 Nov 15 (MJD = 55150). The latest RXTE PCA observation (2009 Nov 17, MJD=55152.17+/-0.02, 2

Archaeoastronomy is a discipline apparently subject to controversy. The reason for this is that it is situated between astronomy, whose tools it uses; and anthropology, archaeology, and history, the disciplines archaeoastronomy serves and within whose epistemological framework should be integrated. Perhaps for this reason, until recently it has not

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This Letter presents an analysis of three-dimensional vector currents and temperatures observed in a sunspot from the photosphere to the chromosphere, spanning a range of heights of approximately 1500 km. With this unique data set, based on novel spectropolarimetric observations of the 850 nm spectral region, it is possible to conduct for the first

According to several properties, the active regions are divided in two groups whose limit is roughly set at 1021 Mx. A statistical analysis indicates that the small regions emerge almost exclusively in the remnant magnetic regions, resulting from the decay of previous active centers. According to these facts, a tentative picture is proposed, where

To investigate the location of the actual limit for the different behavior, the active regions with fluxes greater than 10 to the 20 Mx are investigated. After surveying the differences between large and small active regions reported in the literature, the birthplaces of the active regions are analyzed statistically. The analysis indicates that the