The current and future capabilities of MCP based UV detectors

At the heart of future space-based astronomical UV instruments will be a sensitive UV detector. Though there has been a death of new UV mission opportunities, detector development has continued. Improvements have been made in spatial resolution, dynamic range, detector size, quantum efficiency and background. At the same time the power and mass required to achieve these goals have decreased. We review the current capabilities of microchannel plate based detectors at Berkeley, both in the laboratory and aboard current on-orbit spacecraft. We also discuss what can be expected from the next generation of UV detectors over the next decade.     

UVMag: stellar formation,evolution, structure and environment with space UV and visible spectropolarimetry

Important insights into the formation, structure, evolution and environment of all types of stars can be obtained through the measurement of their winds and possible magnetospheres. However, this has hardly been done up to now mainly because of the lack of UV instrumentation available for long periods of time. To reach this aim, we have designed UVMag, an M-size space mission equipped with a high-resolution spectropolarimeter working in the UV and visible spectral range. The UV domain is crucial in stellar physics as it is very rich in atomic and molecular lines and contains most of the flux of hot stars. Moreover, covering the UV and visible spectral domains at the same time will allow us to study the star and its environment simultaneously. Adding polarimetric power to the spectrograph will multiply tenfold the capabilities of extracting information on stellar magnetospheres, winds, disks, and magnetic fields. Examples of science objectives that can be reached with UVMag are presented for pre-main sequence, main sequence and evolved stars. They will cast new light onto stellar physics by addressing many exciting and important questions. UVMag is currently undergoing a Research & Technology study and will be proposed at the forthcoming ESA call for M-size missions. This spectropolarimeter could also be installed on a large UV and visible observatory (e.g. NASA’s LUVOIR project) within a suite of instruments.     

The Thirty-Meter Telescope: Science and Instrumentation for a Next-Generation Observatory

The Thirty-Meter Telescope international observatory will enable transformational observations over the full cosmic timeline all the way from the first luminous objects in the Universe to the planets and moons of our own solar system. To realize its full scientific potential, TMT will be equipped with a powerful suite of adaptive optics systems and science instruments. Three science instruments will be available at first light: an optical multi-object spectrometer, a near-infrared multi-slit spectrometer and a diffraction-limited near-infrared imager and integral field spectrometer. In addition to these three instruments, a diverse set of new instruments under study will bring additional workhorse capabilities to serve the science interests of a broad user community. The development of TMT instruments represents a large, long-term program that offers a wide range of opportunities to all TMT partners.     

Atmospheric NO from space: the SCIAMACHY capabilities

The SCanning Imaging Absorption spectroMeter for Atmospheric ChartograpHY (SCIAMACHY) has been proposed in 1988 as a payload of the ESA earth observation satellite ENVISAT 1, which is scheduled for launch in 2001 for a four-year mission. SCIAMACHY operates in eight channels covering the UV, the visible and two infrared regions. Recent developments in the testing of the instrument now enable not only the full use of channel 1 (240 nm–314 nm) at a required high level of performance but in some special cases its extension to 220 nm. This instrumental improvement allows new objectives to be addressed in the upper stratoosphere, on top of the already proposed mesospheric and thermospheric investigations of nitric oxide. Simulations show the instrument capabilities for these studies. These NO observations will be performed in solar occultation, lunar occultation and nadir. Previous NO results are reviewed with an emphasis on results obtained by the infrared solar occultation technique as exemplified by the SPACELAB grille spectrometer and other instruments. The capabilities of SCIAMACHY for mapping the total column of upper atmospheric NO is investigated as well as possibilities to infer NO vertical distribution and transfer properties between the different atmospheric regions.     

Long Range Science Perspectives for the VLTI

VLTI interferometry will allow imaging of galactic and extragalactic sources with milliarcsecond angular resolution. For moderately bright sources the spectral resolution will be of the order of 10000. These capabilities will allow detailed studies of solar system objects, stars, proto-planetary systems and the detection of hot extra-solar planets. The observations of galactic nuclei will allow unprecedented measurements of physical parameters in these systems. VLTI will be a prime instrument to study the immediate environment of the massive black hole at the center of the Milky Way. With the exception of a few `self-referencing' sources the observations of extragalactic nuclei will benefit from an extended capability for simultaneous measurements of nearby reference sources for fringe tracking. With beam combination instruments like AMBER, MIDI, PRIMA, and GENIE the VLTI will reach full maturity at a time when other interferometric instruments at different wavelengths will be fully operational. Most important are ALMA (in the mm- and sub-mm-domain), LOFAR and SKA (in the radio meter to centimeter domain) and of course VLB-networks in the radio, and other – at that time –well developed interferometers in the optical. A major scientific potential of future scientific VLTI programs will lie in an efficient combination of these high angular resolution capabilities. This revised version was published online in July 2006 with corrections to the Cover Date.     

High Energy Astrophysics with INTEGRAL

INTEGRAL is an ESA mission scheduled to be launched in 2001. Its fourcoaligned instruments will allow observations of cosmic sources from afraction of a keV to several MeV plus source monitoring in the opticalband. INTEGRAL will be operated as a space observatory and an Announcementof Opportunity to the astronomical community at large will be issued byESA in the spring of the year 2000. Purpose of this paper is to illustrateINTEGRAL capabilities of the three X and Gamma Ray detectors plus opticalmonitor in order to help potential users to write observing proposals.     

Solar System Capabilities of the Thirty Meter Telescope

The TMT Project is completing the design of a telescope with a primary mirror diameter of 30 m, yielding ten times more light gathering power than the largest current telescopes. It is being designed from the outset as a system that will deliver diffraction-limited resolution (8, 15 and 70 milliarcsec at 1.2, 2.2 and 10 microns, respectively) and high Strehl ratios over a 30 arcsecond science field with good performance over a 2 arcmin field. Studies of a representative suite of instruments that span a very large discovery space in wavelength (0.3–30 microns), spatial resolution, spectral resolution and field-of-view demonstrate their feasibility and their tremendous scientific potential. Of particular interest for solar system research, one of these will be IRIS (Infrared Imaging Spectrometer), a NIR instrument consisting of a diffraction-limited imager and an integral-field spectrometer. IRIS will be able to investigate structures with dimensions of only a few tens of kilometers at the distance of Jupiter. Two other instruments, NIRES and MIRES (Near- and Mid IR Echelle Spectrographs) will enable high angular, high spectral resolution observations of solar system objects from the ground with sensitivities comparable to space-based missions. The TMT system is being designed for extremely efficient operation including the ability to rapidly switch to observations with different instruments to take advantage of “targets-of-opportunity” or changing conditions. Thus TMT will provide capabilities that will enable very significant solar system science and be highly synergistic with JWST, ALMA and other planned astronomy missions.     

POLIS: A spectropolarimeter for the VTT and for GREGOR

The polarimetric Littrow Spectrograph POLIS is designed for vector polarimetry at high angular and spectral resolution. It measures the magnetic field simultaneously in the photosphere and the chromosphere of the sun. Both branches of the polarimetry unit are dual beam systems with a single rotating modulator for both wavelengths and polarizing beam splitters in front of each CCD camera. POLIS has been installed at the VTT on Tenerife and has seen First Light on 17 May 2002. A modified version of POLIS will be developed for the balloon mission Sunrise . That version will have UV capabilities down to 200 nm.     

Low-frequency solar radiophysics with LOFAR and FASR

Low-frequency radio observations offer unique diagnostics of the solar corona and solar wind. After a prolongued hiatus, there is renewed interest in this important frequency regime. Two new ground-based instruments will provide critical new low-frequency observations: the low-frequency array (LOFAR) and the frequency agile solar radiotelescope (FASR). This brief topical review summarizes low-frequency radio phenomena that will be accessible to detailed study by LOFAR and FASR in the coming decade. Energy release, drivers of space weather, and studies of the solar wind are emphasized. Both instruments are expected to play important roles in both basic research problems and national and international space weather capabilities. While FASR is a solar-dedicated instrument, LOFAR is not. Solar observing requirements for LOFAR are briefly discussed.     

The 1.5 meter solar telescope GREGOR

The 1.5 m telescope GREGOR opens a new window to the understanding of solar small‐scale magnetism. The first light instrumentation includes the Gregor Fabry Pérot Interferometer (GFPI), a filter spectro‐polarimeter for the visible wavelength range, the GRating Infrared Spectro‐polarimeter (GRIS) and the Broad‐Band Imager (BBI). The excellent performance of the first two instruments has already been demonstrated at the Vacuum Tower Telescope. GREGOR is Europe’s largest solar telescope and number 3 in the world. Its all‐reflective Gregory design provides a large wavelength coverage from the near UV up to at least 5 microns. The field of view has a diameter of 150″. GREGOR is equipped with a high‐order adaptive optics system, with a subaperture size of 10 cm, and a deformable mirror with 256 actuators. The science goals are focused on, but not limited to, solar magnetism. GREGOR allows us to measure the emergence and disappearance of magnetic flux at the solar surface at spatial scales well below 100 km. Thanks to its spectro‐polarimetric capabilities, GREGOR will measure the interaction between the plasma flows, different kinds of waves, and the magnetic field. This will foster our understanding of the processes that heat the chromosphere and the outer layers of the solar atmosphere. Observations of the surface magnetic field at very small spatial scales will shed light on the variability of the solar brightness (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Space astronomy for the mid‐21st century: Robotically maintained space telescopes

The historical development of ground based astronomical telescopes leads us to expect that space‐based astronomical telescopes will need tobe operational for many decades. The exchange of scientific instruments in space will be a prerequisite for the long lasting scientific success of such missions. Operationally, the possibility to repair or replace key spacecraft components in space will be mandatory. We argue that these requirements can be fulfilled with robotic missions and see the development of the required engineering as the main challenge. Ground based operations, scientifically and technically, will require a low operational budget of the running costs. These can be achieved through enhanced autonomy of the spacecraft and mission independent concepts for the support of the software. This concept can be applied to areas where the mirror capabilities do not constrain the lifetime of the mission (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stellar abundances of beryllium and CUBES

Stellar abundances of beryllium are useful in different areas of astrophysics, including studies of the Galactic chemical evolution, of stellar evolution, and of the formation of globular clusters. Determining Be abundances in stars is, however, a challenging endeavor. The two Be II resonance lines useful for abundance analyses are in the near UV, a region strongly affected by atmospheric extinction. CUBES is a new spectrograph planned for the VLT that will be more sensitive than current instruments in the near UV spectral region. It will allow the observation of fainter stars, expanding the number of targets where Be abundances can be determined. Here, a brief review of stellar abundances of Be is presented together with a discussion of science cases for CUBES. In particular, preliminary simulations of CUBES spectra are presented, highlighting its possible impact in investigations of Be abundances of extremely metal-poor stars and of stars in globular clusters.     

TAUVEX - Tel Aviv University UV Explorer

TAUVEX - Tel Aviv University UV Explorer is a space telescope that is currently being built in Israel, to be flown on board the Russian international sattelite SRG - Spectrum Roentgen Gamma, in late 1995 or early 1996. TAUVEX is an imager in the near UV spectral window. Its major goal is to make a survey of about 10% of the UV sky, in the range = 1350 - 3500Å. A successful operation of TAUVEX will partially fill an important gap in our recognition of the sky, namely the distribution and the nature of the celestial UV sources, which are still mostly unknown. TAUVEX will also operate as a fast multicolor photometer in its UV range of operation. TAUVEX is aligned in parallel to the common optical axix of all the other instruments on board SRG, most of which are telescopes and monitors for high energy radiation. SRG will be thus able to perform for the first time in history simultaneous astronomical observations in one and the same celestial body, that cover together 7 order of magnitude of the recorded radiation. The observations of TAUVEX can be greatly enhanced by ground base observations.     

UV astronomy throughout the ages: a historical perspective

Astronomers have long recognized the critical need for ultraviolet imaging, photometry and spectroscopy of stars, planets, and galaxies, but this need could not be satisfied without access to space and the development of efficient instrumentation. When UV measurements became feasible, first with rockets and then with satellites, major discoveries came rapidly. It is true in the UV spectral region as in all others, that significant increases in sensitivity, spectral resolution, and time domain coverage have led to significant new understanding of astrophysical phenomena. I will describe a selection of these discoveries made in each of three eras: (1) the early history of rocket instrumentation and Copernicus, the first UV satellite, (2) the discovery phase pioneered by the IUE, FUSE and EUVE satellites, and (3) the full flowering of UV astronomy with the successful operation of HST and its many instruments. I will also mention a few areas where future UV instrumentation could lead to new discoveries. This review concentrates on developments in stellar and interstellar UV spectroscopy; the major discoveries in galactic, extragalactic, and solar system research are beyond the scope of this review. The important topic of UV technologies and detectors, which enable the remarkable advances in UV astronomy are also not included in this review.     

UV Observations with the Transition Region and Coronal Explorer

The Transition Region and Coronal Explorer is a space-borne solar telescope featuring high spatial and temporal resolution. TRACE images emission from solar plasmas in three extreme-ultraviolet (EUV) wavelengths and several ultraviolet (UV) wavelengths, covering selected ion temperatures from 6000 K to 1 MK. The TRACE UV channel employs special optics to collect high-resolution solar images of the H i L line at 1216 Å, the C iv resonance doublet at 1548 and 1550 Å, the UV continuum near 1550 Å, and also a white-light image covering the spectrum from 2000–8000 Å.We present an analytical technique for creating photometrically accurate images of the C iv resonance lines from the data products collected by the TRACE UV channel. We use solar spectra from several space-borne instruments to represent a variety of solar conditions ranging from quiet Sun to active regions to derive a method, using a linear combination of filtered UV images, to generate an image of solar C iv 1550 Å emission. Systematic and statistical error estimates are also presented. This work indicates that C iv measurements will be reliable for intensities greater than 1014 photons s–1 cm–2 sr–1. This suggests that C iv 1550 Å images will be feasible with statistical error below 20% in the magnetic network, bright points, active regions, flares and other features bright in C iv. Below this intensity the derived image is dominated by systematic error and read noise from the CCD.     

The solar physics Shuttle/Spacelab program and its relationship to studies of the flare build-up

Conclusion The Shuttle/Spacelab program offers an exciting and substantial opportunity for flight of sophisticated instruments for solar research in the 1980's. Problem-oriented missions composed of a number of instruments will be possible as well as flight opportunities for individual instruments developed quickly in response to new knowledge gained from earlier flights. The international scientific community has been asked to participate in defining new facility instruments that are needed. Announcements of Opportunities to participate in the development and use of these instruments will be made by NASA at the appropriate times.     

Next Generation Instrumentation for the Very Large Telescope Interferometer

The scientific capabilities of the VLT Interferometer can be substantially enhanced through new focal-plane instruments. Many interferometric techniques– astrometry, phase-referenced imaging, nulling, and differential phase measurements – require control of the phase to ≲ 1 rad; this capability will be provided at the VLTI by the PRIMA facility. Phase-coherent operation of the VLTI will also make it possible to perform interferometry with spectral resolution up to R ∼ 100,000 by building fiber links to the high-resolution spectrographs UVES and CRIRES. These developments will open new approaches to fundamental problems in fields as diverse as extra solar planets,stellar atmospheres, circumstellar matter, and active galactic nuclei. This revised version was published online in July 2006 with corrections to the Cover Date.     

Laser-induced breakdown spectroscopy with artificial neural network processing for material identification

Laser-induced breakdown spectroscopy (LIBS) has demonstrated its high potential in measurement of material composition in many areas including space exploration. LIBS instruments will be parts of payloads for the 2011 Mars Science Laboratory NASA-led mission and the ExoMars mission planned by ESA. This paper considers application of artificial neural networks (ANN) for material identification based on LIBS spectra that may be obtained with a portable instrument in ambient conditions. The several classes of materials used in this study included those selected to represent the sites analogues to Mars. In addition, metals and aluminum alloys were used to demonstrate ANN capabilities. Excellent material classification is achieved with single-shot measurements in real time.     

Solar magnetism eXplorer (SolmeX)

The magnetic field plays a pivotal role in many fields of Astrophysics. This is especially true for the physics of the solar atmosphere. Measuring the magnetic field in the upper solar atmosphere is crucial to understand the nature of the underlying physical processes that drive the violent dynamics of the solar corona—that can also affect life on Earth. SolmeX, a fully equipped solar space observatory for remote-sensing observations, will provide the first comprehensive measurements of the strength and direction of the magnetic field in the upper solar atmosphere. The mission consists of two spacecraft, one carrying the instruments, and another one in formation flight at a distance of about 200 m carrying the occulter to provide an artificial total solar eclipse. This will ensure high-quality coronagraphic observations above the solar limb. SolmeX integrates two spectro-polarimetric coronagraphs for off-limb observations, one in the EUV and one in the IR, and three instruments for observations on the disk. The latter comprises one imaging polarimeter in the EUV for coronal studies, a spectro-polarimeter in the EUV to investigate the low corona, and an imaging spectro-polarimeter in the UV for chromospheric studies. SOHO and other existing missions have investigated the emission of the upper atmosphere in detail (not considering polarization), and as this will be the case also for missions planned for the near future. Therefore it is timely that SolmeX provides the final piece of the observational quest by measuring the magnetic field in the upper atmosphere through polarimetric observations.