共查询到20条相似文献，搜索用时 31 毫秒
1.
Schwartz R.A. Csillaghy A. Tolbert A.K. Hurford G.J. Mc Tiernan J. Zarro D. 《Solar physics》2002,210(1-2):165-191
The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) performs imaging spectroscopy of the Sun with high spatial
and spectral resolution from 3 keV to 17 MeV using indirect Fourier-transform techniques. We review the rationale behind the
RHESSI data analysis software, and explain the underlying structure of the software tools. Our goal was to make the large
data set available within weeks after the RHESSI launch, and to make it possible for any member of the scientific community
to analyze it easily. This paper describes the requirements for the software and explores our decisions to use the SolarSoftWare
and Interactive Data Language programming packages, to support both Windows and Unix platforms, and to use object-oriented
programming. We also describe how the data are rapidly disseminated and how ancillary data sets are used to enhance the RHESSI
science. Finally, we give a schematic overview of some of the data flow through the high-level analysis tools. More information
on the data and analysis procedures can be found at the RHESSI Data Center website, http://hesperia.gsfc.nasa.gov/rhessidatacenter.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022444531435 相似文献
2.
High-resolution solar hard X-ray imaging on the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) spacecraft is
achieved by a set of rotating modulation collimators. The interpretation of the observed time-modulated X-ray flux in terms
of high-resolution, accurately located images requires continuous, arc-minute roll aspect, which at present is provided by
the `Photo-Multiplier Tube Roll Aspect System' (PMTRAS). This paper describes the PMTRAS operating principles, hardware implementation,
calibration, performance and data analysis approach, with emphasis on its effect on RHESSI imaging. 相似文献
3.
《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
4.
This paper presents an algorithm to decompose the modulated RHESSI light curves into periodic functions and a smooth function,
representing the true (demodulated) time profile of an impulsive source. The decomposition is achieved by optimizing a trade-off
between the Poisson likelihood, a smoothness constraint, and conditions on the average grid transmission and the (modulating
or non-modulating) background. The algorithm, which operates on the level of count rates and does not require imaging information,
is verified by numerical simulations and applied to some early RHESSI data, where – as a preliminary result – several impulsive
features on time scales < 4 s may have been identified. 相似文献
5.
We study the general X-ray and multiwavelength characteristics of microflares of GOES class A0.7 to B7.4 (background subtracted) detected by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 26 September 2003 comparing them with the properties of regular flares. All the events for which X-ray imaging was feasible originated in one active region and were accumulated in areas with intermixed magnetic polarities. During the events’ rise and peak phase, the RHESSI X-ray spectra show a steep nonthermal power-law component (4?γ?10) for energies ??10 keV. Further evidence for the presence of electron beams is provided by the association with radio type III bursts in 5 out of 11 events where AIP radio spectra were available. The strongest event in our sample shows radio signatures of a type II precursor. The thermally emitting flare plasma observed by RHESSI is found to be hot, 11?T?15 MK, with small emission measures, 1046?EM?1047 cm?3, concentrated in the flare loop. In the EUV (TRACE 171 Å), the UV (TRACE 1600 Å) and Kanzelhöhe Solar Observatory Hα, impulsive brightenings at both ends of the RHESSI 3?–?6 keV X-ray loop source are observed, situated in opposite magnetic polarity fields. During the decay phase, a postflare loop at the location of the RHESSI loop source is observed in the TRACE 171 Å? channel showing plasma that is cooled from ??10 MK to ≈?1 MK. Correlations between various thermal and nonthermal parameters derived from the RHESSI microflare spectra compared to the same correlations obtained for a set of small and large flares by Battaglia et al. (Astron. Astrophys. 439, 737, 2005) indicate that the RHESSI instrument gives us a spectrally biased view since it detects only hot (T?10 MK) microflares, and thus the correlations between RHESSI microflare parameters have to be interpreted with caution. The thermal and nonthermal energies derived for the RHESSI microflares are \(\bar{E}_{\mathrm{th}}=7\times 10^{27}\) ergs and \(\bar{E}_{\mathrm{nth}}=2\times 10^{29}\) ergs, respectively. Possible reasons for the order-of-magnitude difference between the thermal and nonthermal microflare energies, which was also found in previous studies, are discussed. The determined event rate of 3.7 h?1 together with the average microflare energies indicate that the total energy in the observed RHESSI microflares is far too small to account for the heating of the active region corona in which they occur. 相似文献
6.
We have used Ramaty High Energy Solar Spectroscopic Imager (RHESSI) modulation profiles in the 25 – 300 keV range to construct
high-fidelity visibilities of 25 flares having at least two components. These hard X-ray visibilities, which are mathematically
identical to the visibilities of radio imaging, were input to software developed for mapping solar flares in the microwave
domain using the Maximum Entropy Method (MEM). We compared and contrasted the MEM maps with Clean and Pixon maps made with
RHESSI software. In particular, we assessed the reliability of the maps and their morphologies for future investigations of
the symmetry of bipolar electron beaming in the sample set. 相似文献
7.
Tomasz Mrozek Szymon Gburek Marek Siarkowski Barbara Sylwester Janusz Sylwester Anna Kepa Magdalena Gryciuk 《Solar physics》2018,293(7):101
In 2009, the Russian Complex Orbital Observations Near-Earth of Activity of the Sun (CORONAS-Photon) spacecraft was launched, carrying the Polish Solar PHotometer In X-rays (SphinX). The SphinX was most sensitive in the spectral range 1.2?–?15 keV, thus an excellent opportunity appeared for comparison with the low-energy end of Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spectra. Common spectral measurements with these instruments cover the range where most of the flare energy is accumulated. We have chosen four consecutive small solar events observed on 4 July 2009 at 13:43 UT, 13:48 UT, 13:52 UT, and 13:55 UT (RHESSI flare peak times) and used them to compare the data and results from the two instruments. Moreover, we included Geostationary Operational Environmental Satellite (GOES) records in our analysis. In practice, the range of comparison performed for SphinX and RHESSI is limited roughly to 3?–?6 keV. RHESSI fluxes measured with a use of one, four, and nine detectors in the 3?–?4 keV energy band agree with SphinX measurements. However, we observed that SphinX spectral irradiances are three times higher than those of RHESSI in the 4?–?6 keV energy band. This effect contributes to the difference in obtained emission measures, but the derived temperatures of plasma components are similar. RHESSI spectra were fitted using a model with two thermal components. We have found that the RHESSI hot component is in agreement with GOES, and the RHESSI hotter component fits the SphinX flaring component well. Moreover, we calculated the so-called thermodynamic measure and the total thermal energy content in the four microflares that we studied. The results obtained show that SphinX is a very sensitive complementary observatory for RHESSI and GOES. 相似文献
8.
Sui Linhui Holman Gordon D. Dennis Brian R. Krucker Säm Schwartz Richard A. Tolbert Kim 《Solar physics》2002,210(1-2):245-259
We have analyzed a C7.5 limb flare observed by RHESSI on 20 February 2002. The RHESSI images appear to show two footpoints
and a loop-top source. Our goal was to determine if the data are consistent with a simple steady-state model in which high-energy
electrons are continuously injected at the top of a semicircular flare loop. A comparison of the RHESSI images with simulated
images from the model has made it possible for us to identify spurious sources and fluxes in the RHESSI images. We find that
the RHESSI results are in many aspects consistent with the model if a thermal source is included between the loop footpoints,
but there is a problem with the spectral index of the loop-top source. The thermal source between the footpoints is likely
to be a low-lying loop interacting with the northern footpoint of a higher loop containing the loop-top source. 相似文献
9.
Curtis D.W. Berg P. Gordon D. Harvey P.R. Smith D.M. Zehnder A. 《Solar physics》2002,210(1-2):115-124
The Ramaty High-Energy Spectroscopic Imager (RHESSI) spacecraft is a NASA Small Explorer (SMEX) class mission. RHESSI is designed
to image solar X-rays and gamma rays with high-energy resolution. The Instrument Data Processing Unit (IDPU) serves as the
central RHESSI instrument on-board data-processing element. It controls and monitors the instrument operations, and provides
a flexible telemetry collection and formatting system. The system responds autonomously to optimize science data collection
over a wide dynamic range of conditions, handling up to 40 Mbps of telemetry during solar flares. This paper presents an overview
of the IDPU hardware and software design. 相似文献
10.
Daniel F. Ryan Aidan M. O’Flannagain Markus J. Aschwanden Peter T. Gallagher 《Solar physics》2014,289(7):2547-2563
We test the compatibility and biases of multi-thermal flare DEM (differential emission measure) peak temperatures determined with AIA with those determined by GOES and RHESSI using the isothermal assumption. In a set of 149 M- and X-class flares observed during the first two years of the SDO mission, AIA finds DEM peak temperatures at the time of the peak GOES 1?–?8 Å flux to have an average of T p=12.0±2.9 MK and Gaussian DEM widths of log10(σ T )=0.50±0.13. From GOES observations of the same 149 events, a mean temperature of T p=15.6±2.4 MK is inferred, which is systematically higher by a factor of T GOES/T AIA=1.4±0.4. We demonstrate that this discrepancy results from the isothermal assumption in the inversion of the GOES filter ratio. From isothermal fits to photon spectra at energies of ?≈6?–?12 keV of 61 of these events, RHESSI finds the temperature to be higher still by a factor of T RHESSI/T AIA=1.9±1.0. We find that this is partly a consequence of the isothermal assumption. However, RHESSI is not sensitive to the low-temperature range of the DEM peak, and thus RHESSI samples only the high-temperature tail of the DEM function. This can also contribute to the discrepancy between AIA and RHESSI temperatures. The higher flare temperatures found by GOES and RHESSI imply correspondingly lower emission measures. We conclude that self-consistent flare DEM temperatures and emission measures require simultaneous fitting of EUV (AIA) and soft X-ray (GOES and RHESSI) fluxes. 相似文献
11.
The Transition Region and Coronal Explorer (TRACE) instrument includes a “white light” imaging capability with novel characteristics.
Many flares with such white-light emission have been detected, and this paper provides an introductory overview of these data.
These observations have 0.5″ pixel size and use the full broad-band response of the CCD sensor; the images are not compromised
by ground-based seeing and have excellent pointing stability as well as high time resolution. The spectral response of the
TRACE white-light passband extends into the UV, so these data capture, for the first time in images, the main radiative energy
of a flare. This initial survey is based on a sample of flares observed at high time resolution for which the Reuven Ramaty
High-Energy Solar Spectroscopic Imager (RHESSI) had complete data coverage, a total of 11 events up to the end of 2004. We
characterize these events in terms of source morphology and contrast against the photosphere. We confirm the strong association
of the TRACE white-light emissions - which include UV as well as visual wavelengths – with hard X-ray sources observed by
RHESSI. The images show fine structure at the TRACE resolution limit, and often show this fine structure to be extended over
large areas rather than just in simple footpoint sources. The white-light emission shows strong intermittency both in space
and in time and commonly contains features unresolved at the TRACE resolution. We detect white-light continuum emission in
flares as weak as GOES C1.6. limited by photon statistics and background solar fluctuations, and support the conclusion of
Neidig (1989) that white-light continuum occurs in essentially all flares. 相似文献
12.
We have analysed 64 flares observed with GOES and RHESSI in the 3.1?–?24.8 keV band (0.5?–?4 Å). Flares were randomly chosen to represent different GOES classes, between B1 and M6. RHESSI was used to image the flaring region on the surface of the Sun. We derived the spatial area of the flare on the surface of the Sun from the imaging observations, scaled it dimensionally to volume, and used the spectroscopically derived emission measure to obtain several flare parameters. We experimented with several imaging methods and selected the use of 50% maximum image photon flux contours to define the flare area (F 50%). Most of the flares showed a single spherical loop-top source. The volume measurement for V, temperature T, and electron density N produced power indices that showed no correlation within the boundaries of error. Larger flares by loop-top source volume are thus neither hotter nor denser. The background-subtracted GOES flux?–?RHESSI Total Emission Measure (TEM RHESSI) and TEM GOES?–?TEM RHESSI dependencies were in agreement with the instrument characteristics and earlier studies. Nonthermal flux was noticed to increase with thermal energy and TEM, which can be said to agree with the “Big Flare Syndrome,” with nonthermal photon flux being considered as one flare manifestation. 相似文献
13.
Slow long-duration events (SLDEs) are flares characterized by the long duration of their rising phase. In many such cases the impulsive phase is weak without typical short-lasting pulses. Instead, smooth, long-lasting hard X-ray (HXR) emission is observed. We analyzed hard X-ray emission and morphology of six selected SLDEs. In our analysis we utilized data from the RHESSI and GOES satellites. The physical parameters of HXR sources were obtained from imaging spectroscopy and were used for the energy balance analysis. The characteristic decay time of the heating rate, after reaching its maximum value, is very long, which explains the long rising phase of these flares. 相似文献
14.
Aschwanden Markus J. Metcalf Thomas R. Krucker Säm Sato Jun Conway Andrew J. Hurford G.J. Schmahl Edward J. 《Solar physics》2004,219(1):149-157
We compare the photometric accuracy of spectra and images in flares observed with the Ramaty High-Energy Solar Spectroscopic
Imager (RHESSI) spacecraft. We test the accuracy of the photometry by comparing the photon fluxes obtained in different energy
ranges from the spectral-fitting software SPEX with those fluxes contained in the images reconstructed with the Clean, MEM,
MEM-Vis, Pixon, and Forward-fit algorithms. We quantify also the background fluxes, the fidelity of source geometries, and
spatial spectra reconstructed with the five image reconstruction algorithms. We investigate the effects of grid selection,
pixel size, field of view, and time intervals on the quality of image reconstruction. The detailed parameters and statistics
are provided in an accompanying CD-ROM and web page. We find that Forward-fit, Pixon, and Clean have a robust convergence
behavior and a photometric accuracy in the order of a few percent, while MEM does not converge optimally for large degrees
of freedom (for large field of view and/or small pixel sizes), and MEM-Vis suffers in the case of time-variable sources. This
comparative study documents the current status of the RHESSI spectral and imaging software, one year after launch.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/B:SOLA.0000021801.83038.aa 相似文献
15.
An association of CMEs with solar flares detected by Fermi γ-ray burst monitor during solar cycle 24
《New Astronomy》2021
By performing certain spatial and temporal criteria, we obtained 492 CME events simultaneously associated with GBM solar flare events (hereafter, GBM-flare–CME) from the total number 5123 Gamma-ray Burst Monitor (GBM) solar flares and 15228 Coronal Mass Ejections (CMEs) detected during the solar cycle 24 (2008–2019). Among these 492 events, which represent about 9.6% of the total number of the detected GBM flares, there are just 381 events (77.4%) representing the CMEs associated with the flares that are detected instantly by both GBM and RHESSI detectors. We found no significant distinction in the results after applying the spatial criteria compared with those arising from applying the temporal criteria only.Actually, all CMEs are ejected within the flare's preflare and the impulsive phases only. From our results, we conclude that the GBM flares whose long duration are most frequently associated with faster and wider CMEs and vice versa. In addition, the longer the flare's duration, the more interval time between the start time of GBM solar flare and CME's ejection time through a linear correlation [Mean Interval = 0.464 × Duration (min)] with a correlation coefficient equals 0.93. We conclude also that, the highly probable, γ-ray emitting flares (detected by GBM only) have a shorter duration and time interval than X-ray flares (detected also by RHESSI). As well as the GBM - CMEs events, without RHESSI associated CMEs are faster and wider than those associated with RHESSI events. 相似文献
16.
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
17.
Saint-Hilaire Pascal von Praun Christoph Stolte Etzard Alonso Gustavo Benz Arnold O. Gross Thomas 《Solar physics》2002,210(1-2):143-164
The RHESSI Experimental Data Center (HEDC) at ETH Zürich aims to facilitate the use of RHESSI data. It explores new ways to
speed up browsing and selecting events such as solar flares. HEDC provides pre-processed data for on-line use and allows basic
data processing remotely over the Internet. In this article, we describe the functionality and contents of HEDC, as well as
first experiences by users. HEDC can be accessed at http://www.hedc.ethz.ch. Additional graphical material and color versions of most figures are available on the CD-ROM accompanying this volume.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1022413302246 相似文献
18.
We investigate the radiative and conductive cooling in the solar flare observed by RHESSI on 2005 September 13. The radiative
and conductive loss energies are estimated from the observations after the flare onset. Consistent with previous findings,
the cooling is increased with time, especially the radiation becomes remarkable on the later phase of flare. According our
method, about half of thermal energy is traced by RHESSI soft X-rays, while the other half is lost by the radiative (∼38%)
and conductive (∼9%) cooling at end of the hard X-rays in this event. The nonthermal energy input of P
nth (inferred from RHESSI hard X-ray spectrum) is not well correlated with the derivative of thermal energy of
\fracdEthdt\frac{\mathrm{d}E_{\mathrm{th}}}{\mathrm{d}t} (required to radiate the RHESSI soft X-ray flux and spectrum) alone. However, after consideration the radiation and conduction,
a high correlation is obtained between the derivative of total thermal energy (
\fracdEth+Erad+Econddt\frac{\mathrm{d}E_{\mathrm{th}}+E_{\mathrm{rad}}+E_{\mathrm{cond}}}{\mathrm{d}t}) and nonthermal energy input (P
nth) from the flare start to end, indicating the relative importance of conductive and direct radiative losses during the solar
flare development. Ignoring the uncertainties to estimate the energy from the observations, we find that about ∼12% fraction
of the known energy is transferred into the thermal energy for the 2005 September 13 flare. 相似文献
19.
The RHESSI Spectrometer 总被引：2，自引：0，他引：2
Smith D.M. Lin R.P. Turin P. Curtis D.W. Primbsch J.H. Campbell R.D. Abiad R. Schroeder P. Cork C.P. Hull E.L. Landis D.A. Madden N.W. Malone D. Pehl R.H. Raudorf T. Sangsingkeow P. Boyle R. Banks I.S. Shirey K. Schwartz Richard 《Solar physics》2002,210(1-2):33-60
RHESSI observes solar photons over three orders of magnitude in energy (3 keV to 17 MeV) with a single instrument: a set of
nine cryogenically cooled coaxial germanium detectors. With their extremely high energy resolution, RHESSI can resolve the
line shape of every known solar gamma-ray line except the neutron capture line at 2.223 MeV. High resolution also allows clean
separation of thermal and non-thermal hard X-rays and the accurate measurement of even extremely steep power-law spectra.
Detector segmentation, fast signal processing, and two sets of movable attenuators allow RHESSI to make high-quality spectra
and images of flares across seven orders of magnitude in intensity. Here we describe the configuration and operation of the
RHESSI spectrometer, show early results on in-flight performance, and discuss the principles of spectroscopic data analysis
used by the RHESSI software. 相似文献
20.
A. M. Urnov S. V. Shestov S. A. Bogachev F. F. Goryaev I. A. Zhitnik S. V. Kuzin 《Astronomy Letters》2007,33(6):396-410
Our main goal is to show that the spatial and temporal dynamics of the temperature content for plasma structures in the solar corona can be described quantitatively in principle, which is necessary for understanding the formation mechanisms of soft X-ray emission. An approach based on a consistent modeling of complex data from the CORONAS-F, GOES, and RHESSI satellites is suggested. A basically new element of this approach is the use of time series of monochromatic full-Sun images in the X-ray MgXII 8.42 Å line and EUV lines obtained in the SPIRIT experiment onboard CORONAS-F. Two inversion procedures have been used to determine the volume and column differential emission measures defined by the Stieltjes integral: an optimization one based on a multitemperature parametric model and an iterative one based on the Bayesian theorem, respectively. The calculations with coronal abundances agree with the RHESSI data within the experimental error limits, while those with photospheric abundances give no satisfactory agreement. The relatively cold (with temperature 2–4 MK) and transient (4–10 MK) plasmas are shown to play a significant role in producing soft X-ray emission during flare events and in their energy budget. The spatial electron density and temperature distributions and their time evolution have been obtained for long-duration events that were first observed in the monochromatic MgXII channel and were previously called “spiders.” The method used has allowed us to verify the absolute intercalibration of the fluxes recorded in all experiments and to reference the SPIRIT MgXII images to the solar disk. We also consider possible flare plasma heating mechanisms for impulsive and long-duration (spider) flare events. 相似文献