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1.
《Solar physics》2002,210(1-2):3-32
RHESSI is the sixth in the NASA line of Small Explorer (SMEX) missions and the first managed in the Principal Investigator
mode, where the PI is responsible for all aspects of the mission except the launch vehicle. RHESSI is designed to investigate
particle acceleration and energy release in solar flares, through imaging and spectroscopy of hard X-ray/gamma-ray continua
emitted by energetic electrons, and of gamma-ray lines produced by energetic ions. The single instrument consists of an imager,
made up of nine bi-grid rotating modulation collimators (RMCs), in front of a spectrometer with nine cryogenically-cooled
germanium detectors (GeDs), one behind each RMC. It provides the first high-resolution hard X-ray imaging spectroscopy, the
first high-resolution gamma-ray line spectroscopy, and the first imaging above 100 keV including the first imaging of gamma-ray
lines. The spatial resolution is as fine as ∼ 2.3 arc sec with a full-Sun (≳ 1°) field of view, and the spectral resolution
is ∼ 1–10 keV FWHM over the energy range from soft X-rays (3 keV) to gamma-rays (17 MeV). An automated shutter system allows
a wide dynamic range (>107) of flare intensities to be handled without instrument saturation. Data for every photon is stored in a solid-state memory
and telemetered to the ground, thus allowing for versatile data analysis keyed to specific science objectives. The spin-stabilized
(∼ 15 rpm) spacecraft is Sun-pointing to within ∼ 0.2° and operates autonomously. RHESSI was launched on 5 February 2002,
into a nearly circular, 38° inclination, 600-km altitude orbit and began observations a week later. The mission is operated
from Berkeley using a dedicated 11-m antenna for telemetry reception and command uplinks. All data and analysis software are
made freely and immediately available to the scientific community.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022428818870 相似文献
2.
N. Barrière P. von Ballmoos H. Halloin N. Abrosimov J. M. Alvarez K. Andersen P. Bastie S. Boggs P. Courtois T. Courvoisier M. Harris M. Hernanz J. Isern P. Jean J. Knödlseder G. Skinner B. Smither P. Ubertini G. Vedrenne G. Weidenspointner C. Wunderer 《Experimental Astronomy》2005,20(1-3):269-278
The next generation of instrumentation for nuclear astrophysics will have to achieve a factor of 10–100 improvement in sensitivity over present technologies. With the focusing gamma-ray telescope MAX we take up this challenge: combining unprecedented sensitivity with high spectral and angular resolution, and the capability of measuring the polarization of the incident photons. The feasibility of such a crystal diffraction gamma-ray lens has recently been demonstrated with the prototype lens CLAIRE. MAX is a proposed mission which will make use of satellite formation flight to achieve 86 m focal length, with the Laue lens being carried by one satellite and the detector by the other. In the current design, the Laue diffraction lens of MAX will consist of 13740 copper and germanium (Ge1−x
Si
x
, x ∼ 0.02) crystal tiles arranged on 36 concentric rings. It simultaneously focuses in two energy bands, each centred on one of the main scientific objectives of the mission: the 800–900 keV band is dedicated to the study of nuclear gamma-ray lines from type Ia supernovae (e.g. 56 Co decay line at 847 keV) while the 450–530 keV band focuses on electron-positron annihilation (511 keV emission) from the Galactic centre region with the aim of resolving potential point sources. MAX promises a breakthrough in the study of point sources at gamma-ray energies by combining high narrow-line sensitivity (better than 10−6 cm−2 s−1) and high energy resolution (E/dE ∼ 500). The mission has successfully undergone a pre-phase A study with the French Space Agency CNES, and continues to evolve: new diffracting materials such as bent or composite crystals seem very promising.
PACS: 95.55.Ka, 29.30.Kv, 61.10.-i 相似文献
3.
The employment of a large area Phase Fresnel Lens (PFL) in a gamma-ray telescope offers the potential to image astrophysical phenomena with micro-arcsecond (μ′′) angular resolution [1]. In order to assess the feasibility of this concept, two detailed studies have been conducted of formation flying missions in which a Fresnel lens capable of focussing gamma-rays and the associated detector are carried on two spacecraft separated by up to 106 km. These studies were performed at the NASA Goddard Space Flight Center Integrated Mission Design Center (IMDC) which developed spacecraft, orbital dynamics, and mission profiles. The results of the studies indicated that the missions are challenging but could be accomplished with technologies available currently or in the near term. The findings of the original studies have been updated taking account of recent advances in ion thruster propulsion technology. 相似文献
4.
A. Hofmann K. Arlt H. Balthasar S.M. Bauer W. Bittner J. Paschke E. Popow J. Rendtel D. Soltau T. Waldmann 《Astronomische Nachrichten》2012,333(9):854-862
The new Solar telescope GREGOR is designed to observe small‐scale dynamic magnetic structures below a size of 70 km on the Sun with high spectral resolution and polarimetric accuracy. For this purpose, the polarimetric concept of GREGOR is based on a combination of post‐focus polarimeters with pre‐focus equipment for high precision calibration. The Leibniz‐Institute for Astrophysics Potsdam developed the GREGOR calibration unit which is an integral part of the telescope. We give an overview of the function and design of the calibration unit and present the results of extensive testing series done in the Solar Observatory “Einsteinturm” and at GREGOR (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
5.
The Reuven Ramaty High-Energy Solar Spectroscopic Imager RHESSI telescope produces hard X-ray images by Fourier imaging techniques
that are capable of determining the sizes and shapes of sources with spatial scales in the range ∼ 2′′–180′′. Applying the
method of Unpixelized Forward Fitting to RHESSI modulation profiles from simple flares, we have identified the presence of
`halo' sources whose size scale (∼ 40′′) greatly exceeds the `core' sizes (≤ 6′′–14′′). Although such `core-halo' structures
have been observed at radio wavelengths using a similar technique, the radio and hard X-ray phenomena may be different. These
observations raise questions about the nature of these `halos'. Among the possibilities are that they are albedo sources,
thin-target loops, or unidentified diffuse structures.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022484822851 相似文献
6.
COR1 is the innermost coronagraph of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite
aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. The paired COR1 telescopes observe the white-light K-corona from 1.4 to 4 solar radii in a waveband
22.5 nm wide centered on the Hα line at 656 nm. An internal polarizer allows the measurement of both total and polarized brightness.
The co-alignment of the two COR1 telescopes is derived from the star λ Aquarii for the Ahead spacecraft, and from an occultation
of the Sun by the Moon for Behind. Observations of the planet Jupiter are used to establish absolute photometric calibrations
for each telescope. The intercalibration of the two COR1 telescopes are compared using coronal mass ejection observations
made early in the mission, when the spacecraft were close together. Comparisons are also made with the Solar and Heliospheric
Observatory (SOHO) Large Angle and Spectrometric Coronagraph (LASCO) C2 and Mauna Loa Solar Observatory Mk4 coronagraphs. 相似文献
7.
Oleg Malkov Mikhail Sachkov Boris Shustov Pavel Kaigorodov Francisco Javier Yáñez Ana Ines Gómez de Castro 《Astrophysics and Space Science》2011,335(1):323-327
We present scientific program construction principles and a time allocation scheme developed for the World Space Observatory—Ultraviolet
(WSO-UV) mission, which is an international space observatory for observation in UV spectral range 100–300 nm. The WSO-UV
consists of a 1.7 m aperture telescope with instrumentation designed to carry out high resolution spectroscopy, long-slit
low resolution spectroscopy and direct sky imaging. The WSO-UV Ground Segment is under development by Spain and Russia. They
will coordinate the Mission and Science Operations and provide the satellite tracking stations for the project. 相似文献
8.
COR1 is an internally occulted Lyot coronagraph, part of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI)
instrument suite aboard the twin Solar Terrestrial Relations Observatory (STEREO) spacecraft. Because the front objective lens is subjected to a full solar flux, the images are dominated by instrumental
scattered light which has to be removed to uncover the underlying K corona data. We describe a procedure for removing the
instrumental background from COR1 images. F coronal emission is subtracted at the same time. The resulting images are compared
with simultaneous data from the Mauna Loa Solar Observatory Mk4 coronagraph. We find that the background subtraction technique
is successful in coronal streamers, while the baseline emission in coronal holes (i.e. between plumes) is suppressed. This is an expected behavior of the background subtraction technique. The COR1 radiometric
calibration is found to be either 10 – 15% lower, or 5 – 10% higher than that of the Mk4, depending on what value is used
for the Mk4 plate scale, while an earlier study found the COR1 radiometric response to be ∼ 20% higher than that of the Large
Angle Spectroscopic Coronagraph (LASCO) C2 telescope. Thus, the COR1 calibration is solidly within the range of other operating
coronagraphs. The background levels in both COR1 telescopes have been quite steady in time, with the exception of a single
contamination event on 30 January 2009. Barring too many additional events of this kind, there is every reason to believe
that both COR1 telescopes will maintain usable levels of scattered light for the remainder of the STEREO mission. 相似文献
9.
Olga Popova 《Earth, Moon, and Planets》2004,95(1-4):303-319
The fate of entering meteoroids in atmosphere is determined by their size, velocity and substance properties. Material from
ablation of small-sized meteors (roughly R≤0.01–1 cm) is mostly deposited between 120 and 80 km altitudes. Larger bodies (up to meter sizes) penetrate deeper into the
atmosphere (down to 20 km altitude). Meteoroids of cometary origin typically have higher termination altitude due to substance
properties and higher entry velocity. Fast meteoroids (V>30–40 km/s) may lose a part of their material at higher altitudes due to sputtering. Local flow regime realized around the
falling body determines the heat transfer and mass loss processes. Classic approach to meteor interaction with atmosphere
allows describing two limiting cases: – large meteoroid at relatively low altitude, where shock wave is formed (hydrodynamical
models); – small meteoroid/or high altitudes – free molecule regime of interaction, which assumes no collisions between evaporated
meteoroid particles. These evaporated particles form initial train, which then spreads into an ambient air due to diffusion.
Ablation models should make it possible to describe physical conditions that occur around meteor body. Several self-consistent
hydrodynamical models are developed, but similar models for transition and free molecule regimes are still under study. This
paper reviews existing ablation models and discusses model boundaries. 相似文献
10.
V2213 Cyg was discovered as a variable star by Pavlenko (1999) in 1998. We present our photometry of V2213 Cyg from 1998–2003
based on CCD observations with the K-380 Cassegrain telescope of CrAO and the 60 cm Zeiss telescope of SAI. Observations have
been carried out mostly in R and sometimes in B and V Johnson system. The total amount of data is 2270 points, covering ∼50 nights. We classify this binary as a W UMa-type contact
system. Using all data we determined the orbital period to be 0.350079 ± 0.000007 day. The mean brightness varies between
R = 14.35 and 14.05. The mean 1999–2003 orbital light curve has two humps and a primary minimum (I), which is 0.04 mag brighter
than the deeper secondary one (II). The mean humps have slightly different height. The difference between two individual maxima
varies within 0.1 mag, which may indicate an activity of the components. The highest hump is an asymmetrical one: it has sort
of a shoulder at phases 0.75–0.80, before entering the less deep primary minimum (phase 0.0). The system is rather reddened,
its colour indices are: B−V ∼ 0.8 and V−R ∼ 0.7, and give a spectral class of V2213 Cyg earlier than K. 相似文献
11.
Morgenthaler Jeffrey P. Harris Walter M. Scherb Frank Doane Nathaniel E. Oliversen Ronald J. 《Earth, Moon, and Planets》2002,90(1-4):89-97
We present hydrogen Balmer-α spectra of comet C/1995 O1(Hale–Bopp) recorded on 5 nights from 1997 February 1 to April 19 by
ahigh-resolution (Δ v = 5 km s-1) Fabry–Pérot spectrometer for a4'.1 (∼2.7 × 105 km) FOV centered 5' sunwardof the nucleus. The Hα line profile is an important diagnostic ofphotolytic heating in cometary
atmospheres. Extraction of the spectrafrom the Fabry–Pérot ring images was complicated by obscuration of the telescope FOV
due to Hale–Bopp's low elevation, but the measuredH-α line widths of 11–13 km s-1 (FWHM) are insensitive to the spectral extraction technique. The line widths are consistent withestimates derived from a
successful model of Hale–Bopp's hydrogenLyman-α coma assuming the inner coma is opaque to Hα. Wediscuss methods for improving
the spectral extraction technique andderiving a precise instrument profile which will allow the detailedshape of the line
profile to constrain coma models. 相似文献
12.
Warell Johan LAGERKVIST CLAES-INGVAR Lageros JOHAN S. V. 《Earth, Moon, and Planets》1997,78(1-3):197-203
Dust continuum imaging of comet C/1995 O1 (Hale-Bopp) was carried out with the Swedish Vacuum Solar Telescope (SVST)on La
Palma in April, 1997. Images were reduced according to standard procedure, aligned, averaged, navigated and enhanced with
azimuthal renormalization, rotational derivative, temporal derivative and unsharp masking processing.
The rotational period of the nucleus was determined to 11.5 h and the mean projected dust outflow velocity to 0.41 km s−1. Shell envelopes in the sunward side of the coma were separated by a projected distance of ∼15 000–20 000 km and spiralling
inwards towards smaller radii in the direction of local evening. Small scale inhomogeneities of size 1 000–2 000 km, interpreted
as correlated with variations in dust emission activity, were seen at radii ≤20 000 km. Two overlapping shell systems with
a relative lag angle of ∼55° were evident at the time.
The north pole of the nucleus was directed towards the Earth. The dust emission pattern is very complex and may be due to
several active areas. The shape of the incomplete spiral shell pattern indicates that the angle between the line-of-sight
and the rotational axis of the nucleus was not large.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
13.
In 2004 and 2005 CNES decided to perform phase 0 studies on 4 scientific missions: ASPICS (Solar physics), MAX (γ-rays Laue lens), PEGASE (hot Jupiter study by an interferometer in the 2μm to 4.5μm range) and SIMBOL-X (hard X-rays telescope). This last mission had already undergone a feasibility study in 2003 (ref. [4]), however a complementary study was necessary to take into account the possibilities of increasing the payload mass allowance, as well as the developments in the payload design and science goals (see ref. [1]). The output of this new detailed study is described hereafter. 相似文献
14.
The international Rosetta mission, a cornerstone mission of the european space agency scientific Programme, was launched on 2nd March 2004 on its 10 years journey towards a rendezvous with comet Churyumov-Gerasimenko (Gardini et al., 1999). During its interplanetary flight towards its target Rosetta crosses the asteroid belt twice with the opportunity to observe at close quarters two asteroids: (2867)-Šteins in 2008 and (21)-Lutetia in 2010. The spacecraft design was such that these opportunities could be fully exploited to deliver valuable data to the scientific community. The mission trajectory was controlled such that Rosetta would fly next to asteroid Šteins on the 5th of September 2008 with a relative speed of 8.6 km/s at a minimum distance of 800 km. Mission operations have been carefully planned to achieve the best possible flyby scenario and scientific outcome. The flyby scenario, the optical navigation campaign, and the planning of the scientific observations had to be adapted by the Mission and the Science Operations Centres to the demanding requirements expressed by the scientific community. The flyby was conducted as planned with a large number of successful observations. 相似文献
15.
T. Shimizu S. Nagata S. Tsuneta T. Tarbell C. Edwards R. Shine C. Hoffmann E. Thomas S. Sour R. Rehse O. Ito Y. Kashiwagi M. Tabata K. Kodeki M. Nagase K. Matsuzaki K. Kobayashi K. Ichimoto Y. Suematsu 《Solar physics》2008,249(2):221-232
The Hinode Solar Optical Telescope (SOT) is the first space-borne visible-light telescope that enables us to observe magnetic-field
dynamics in the solar lower atmosphere with 0.2 – 0.3 arcsec spatial resolution under extremely stable (seeing-free) conditions.
To achieve precise measurements of the polarization with diffraction-limited images, stable pointing of the telescope (<0.09 arcsec,
3σ) is required for solar images exposed on the focal plane CCD detectors. SOT has an image stabilization system that uses image
displacements calculated from correlation tracking of solar granules to control a piezo-driven tip-tilt mirror. The system
minimizes the motions of images for frequencies lower than 14 Hz while the satellite and telescope structural design damps
microvibration in higher frequency ranges. It has been confirmed from the data taken on orbit that the remaining jitter is
less than 0.03 arcsec (3σ) on the Sun. This excellent performance makes a major contribution to successful precise polarimetric measurements with 0.2 – 0.3 arcsec
resolution.
K. Kobayashi now at NASA/Marshall Space Flight Center, Huntsville, AL 35812, USA. 相似文献
16.
Jürgen Knödlseder Peter von Ballmoos Filippo Frontera Angela Bazzano Finn Christensen Margarida Hernanz Cornelia Wunderer 《Experimental Astronomy》2009,23(1):121-138
The gamma-ray imager (GRI) is a novel mission concept that will provide an unprecedented sensitivity leap in the soft gamma-ray
domain by using for the first time a focusing lens built of Laue diffracting crystals. The lens will cover an energy band
from 200–1,300 keV with an effective area reaching 600 cm2. It will be complemented by a single reflection multilayer coated mirror, extending the GRI energy band into the hard X-ray
regime, down to ∼10 keV. The concentrated photons will be collected by a position sensitive pixelised CZT stack detector.
We estimate continuum sensitivities of better than 10 − 7 ph cm − 2s − 1keV − 1 for a 100 ks exposure; the narrow line sensitivity will be better than 3 × 10 − 6 ph cm − 2s − 1 for the same integration time. As focusing instrument, GRI will have an angular resolution of better than 30 arcsec within
a field of view of roughly 5 arcmin—an unprecedented achievement in the gamma-ray domain. Owing to the large focal length
of 100 m of the lens and the mirror, the optics and detector will be placed on two separate spacecrafts flying in formation
in a high elliptical orbit. R&D work to enable the lens focusing technology and to develop the required focal plane detector
is currently underway, financed by ASI, CNES, ESA, and the Spanish Ministery of Education and Science. The GRI mission has
been proposed as class M mission for ESAs Cosmic Vision 2015–2025 program. GRI will allow studies of particle acceleration
processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent
and most energetic processes in the universe.
All authors are on behalf of a large international collaboration
The GRI mission has been proposed as an international collaboration between (in alphabetical order) Belgium (CSR), China (IHEP,
Tsinghua Univ.), Denmark (DNSC, Southern Univ.), France (CESR, APC, ILL, CSNSM, IAP, LAM), Germany (MPE), Ireland (UCD School
of Physics), Italy (INAF/IASF Rome, Bologna, Milano, Palermo; INAF/OA Brera, Roma; UNIFE, CNR/IMEM), Poland (NCAC), Portugal
(Combra Univ., Evora Univ.), Russia (SINP, MSU, Ioffe Inst.), Spain (IEEC-CSIC-IFAE, CNM-IMB), the Netherlands (SRON, Utrecht
Univ.), Turkey (Sabanci Univ.), United Kingdom (Univ. of Southampton, MSSL, RAL, Edinburgh Univ.), and the United States of
America (SSL UC Berkeley, Argonne National Lab., MSFC, GSFC, US NRL). 相似文献
17.
Plots of 12-month moving averages of the radio emission values for 1947–2002 indicated that the ratios (maximum/minimum) of
the solar cycles 19–23 were low (∼ 1.2) in the upper chromosphere and lower corona (frequencies near 15 000 MHz), rose to
maximum levels of ∼ 3.5 in the middle corona (frequencies ∼ 2000±500 MHz), and dropped thereafter to ∼ 2.5. In some cycles,
there were two maxima separated by about 2 years. In cycles 20 and 23, mostly the second maximum was larger than the first
maximum, but in cycles 21 and 22, some parameters showed the first maximum larger while others showed the second maximum larger.
There was no systematic shift from first maximum to second maximum, with frequency or temperature (or altitude). 相似文献
18.
The Space Infrared telescope for Cosmology and Astrophysics (SPICA) is planned to be the next space astronomy mission observing
in the infrared. The mission is planned to be launched in 2017 and will feature a 3.5 m telescope cooled to <5 K through the
use of mechanical coolers. These coolers will also cool the focal plane instruments thus avoiding the use of consumables and
giving the mission a long lifetime. SPICA’s large, cold aperture will provide a two order of magnitude sensitivity advantage
over current far infrared facilities (>30 microns wavelength). We describe the scientific advances that will be made possible
by this large increase in sensitivity and give details of the mission, spacecraft and focal plane conceptual design.
相似文献
Bruce SwinyardEmail: |
19.
We have used the 40 cm coronagraph with an inverse occulting disk to observe the limb darkening free of instrumental stray
light. Our results agree remarkably well with those of Petro et al. (1984, Astrophys. J.
283, 426) who used the McMath – Pierce tower telescope but employed a different correction procedure for instrumental stray light
than Neckel and Labs (1994, Solar Phys.
153, 91), whose results for λ=445.1 nm deviate systematically, apparently overcorrecting for stray light. Future continuation of such highly reproducible
measurements offers an interesting independent diagnostic of possible slow trends in effective temperature (T
eff) and in total solar irradiance. 相似文献
20.
Mars environment and magnetic orbiter model payload 总被引:1,自引:0,他引:1
B. Langlais F. Leblanc T. Fouchet S. Barabash D. Breuer E. Chassefière A. Coates V. Dehant F. Forget H. Lammer S. Lewis M. Lopez-Valverde M. Mandea M. Menvielle A. Pais M. Paetzold P. Read C. Sotin P. Tarits S. Vennerstrom G. Branduardi-Raymont G. Cremonese J. G. M. Merayo T. Ott H. Rème J. G. Trotignon J. E. Walhund 《Experimental Astronomy》2009,23(3):761-783
Mars Environment and Magnetic Orbiter was proposed as an answer to the Cosmic Vision Call of Opportunity as a M-class mission.
The MEMO mission is designed to study the strong interconnections between the planetary interior, atmosphere and solar conditions
essential to understand planetary evolution, the appearance of life and its sustainability. MEMO provides a high-resolution,
complete, mapping of the magnetic field (below an altitude of about 250 km), with an yet unachieved full global coverage.
This is combined with an in situ characterization of the high atmosphere and remote sensing of the middle and lower atmospheres,
with an unmatched accuracy. These measurements are completed by an improved detection of the gravity field signatures associated
with carbon dioxide cycle and to the tidal deformation. In addition the solar wind, solar EUV/UV and energetic particle fluxes
are simultaneously and continuously monitored. The challenging scientific objectives of the MEMO mission proposal are fulfilled
with the appropriate scientific instruments and orbit strategy. MEMO is composed of a main platform, placed on a elliptical
(130 × 1,000 km), non polar (77° inclination) orbit, and of an independent, higher apoapsis (10,000 km) and low periapsis
(300 km) micro-satellite. These orbital parameters are designed so that the scientific return of MEMO is maximized, in terms
of measurement altitude, local time, season and geographical coverage. MEMO carry several suites of instruments, made of an
‘exospheric-upper atmosphere’ package, a ‘magnetic field’ package, and a ‘low-middle atmosphere’ package. Nominal mission
duration is one Martian year. 相似文献