This paper describes the main characteristics of GRIS (GREGOR Infrared Spectrograph), the grating spectrograph installed in the recently inaugurated (May 2012) 1.5-meter GREGOR telescope located at the Observatorio del Teide in Tenerife. The spectrograph has a standard Czerny-Turner configuration with parabolic collimator and camera mirrors that belong to the same conic surface. Although nothing prevents its use at visible wavelengths, the spectrograph will be initially used in combination with the infrared detector of the Tenerife Infrared Polarimeter (TIP-II) in standard spectroscopic mode as well as for spectropolarimetric measurements.
We evaluate the exposure during nadir observations with JEM-EUSO, the Extreme Universe Space Obser-\ud
vatory, on-board the Japanese Experiment Module of the International Space Station. Designed as a mis-\ud
sion to explore the extreme energy Universe from space, JEM-EUSO will monitor the Earth’s nighttime\ud
atmosphere to record the ultraviolet light from tracks generated by extensive air showers initiated by\ud
ultra-high energy cosmic rays. In the present work, we discuss the particularities of space-based obser-\ud
vation and we compute the annual exposure in nadir observation. The results are based on studies of the\ud
expected trigger aperture and observational duty cycle, as well as, on the investigations of the effects of\ud
clouds and different types of background light. We show that the annual exposure is about one order of\ud
magnitude higher than those of the presently operating ground-based observatories
n this paper we describe the main characteristics of the JEM-EUSO instrument. The Extreme Universe Space Observatory on the Japanese Experiment Module (JEM-EUSO) of the International Space Station (ISS) will observe Ultra High-Energy Cosmic Rays (UHECR) from space. It will detect UV-light of Extensive Air Showers (EAS) produced by UHECRs traversing the Earth's atmosphere. For each event, the detector will determine the energy, arrival direction and the type of the primary particle. The advantage of a space-borne detector resides in the large field of view, using a target volume of about 10(12) tons of atmosphere, far greater than what is achievable from ground. Another advantage is a nearly uniform sampling of the whole celestial sphere. The corresponding increase in statistics will help to clarify the origin and sources of UHECRs and characterize the environment traversed during their production and propagation. JEM-EUSO is a 1.1 ton refractor telescope using an optics of 2.5 m diameter Fresnel lenses to focus the UV-light from EAS on a focal surface composed of about 5,000 multi-anode photomultipliers, for a total of a parts per thousand integral 3a <...10(5) channels. A multi-layer parallel architecture handles front-end acquisition, selecting and storing valid triggers. Each processing level filters the events with increasingly complex algorithms using FPGAs and DSPs to reject spurious events and reduce the data rate to a value compatible with downlink constraints
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