ELMER is a multi-purpose Camera&Spectrograph in the optical range for the GTC. ELMERs electro-mechanical design was based in well known, straightforward and reliable solutions, hence each mechanism is based in a wheel driven by a pre-loaded worm gear transmission, except focusing of the focal plane on the CCD which is based in a translation stage

We have analyzed spectroscopic earthshine data to determine Earth's nightly spectral albedos covering the visible, near and middle infrared spectral ranges. Observations in the visible were undertaken from Palomar Observatory with the spectrograph in the Palomar 60" telescope and with the echelle spectrograph of the InfraRed Telescope Facility

We present ESO-NTT low resolution spectroscopy of the neutron star X-ray transient Cen X-4 in quiescence over a complete orbital cycle. Our data reveal the presence of a K3-7 V companion which contributes 63% to the 5600-6900 Å flux and orbits the neutron star with a velocity semi-amplitude of K_2=145.8± 1.0 km s-1. This, combined with a previous

A good alternative to traditional methods of passing on astronomical concepts is to use a 'collateral' story that catches the public's attention. It may also simultaneously give a vital opportunity to awaken the critical faculty that often seems so perilously close to extinction these days. The recipe is simple: nothing but an actor or actress, his

We report the discovery of twin kilohertz quasi-periodic oscillations (kHz QPOs) in the X-ray flux of XTE J1807-294, the fourth accreting millisecond pulsar (AMP). This is the second AMP exhibiting twin kHz QPOs. In contrast to the first case, SAX J1808.4-3658, the frequency separation Δν between these kHz QPOs is consistent with the pulse

It is well known that when measuring electron densities in H II regions locally via emission line ratios the values observed are 100cm-3, but gobal values obtained via emission measure using surface brightness as the observed parameter are ~1cm-3. This difference is attributable to density fluctuations,and traditional models for these is the `