The Instituto de Astrofísica de Canarias (IAC), Spain, together with the Spanish company Tecdis Displays Ibérica, S.A., are developing voltage tunable optical retarders using liquid crystals as phase retarding medium. The ROCLIs are built for being used in the Imaging Magnetograph eXperiment (IMaX), which is one of the instruments aboard of the

The description of the Imaging Magnetograph eXperiment (IMaX) is presented in this contribution. This is a magnetograph which will fly by the end of 2006 on a stratospheric balloon, together with other instruments (to be described elsewhere). Especial emphasis is put on the scientific requirements to obtain diffraction-limited visible magnetograms

IAUC 8072 available at Central Bureau for Astronomical Telegrams.

We present an overview of the spectral variability of the peculiar F-type hypergiant ρ Cas, obtained from our long-term monitoring campaigns over the past 8.5 yr with four spectrographs in the northern hemisphere. Between 2000 June and September an exceptional variability phase occurred when the V brightness dimmed by about a full magnitude. The

EMIR is a multiobject intermediate resolution (R ≍ 4000) near infrared spectrograph with image capabilities to be mounted on the Gran Telescopio Canarias (GTC). EMIR shall provide image and spectra of a wide FOV (6x6 arcmin in imaging mode and 6x4 arcmin in multiobject spectroscopic mode), and will use grisms as dispersive elements. The use of

Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. This paper will discuss in some detail the final Commissioning Instrument (CI) mechanical design and