Detailed Calibration of the Off-Axis Optical Characteristics for the X-Ray Telescope onboard Hinode

2020 ◽  
Author(s):  
Junho Shin ◽  
Takashi Sakurai ◽  
Ryouhei Kano ◽  
Yong-Jae Moon ◽  
Yeon-Han Kim
Keyword(s):  
Solar Corona ◽  
Energy Dependence ◽  
Scattered Light ◽  
Field Of View ◽  
Coronal Plasma ◽  
Optical Characteristics ◽  
Optical Center ◽  
Wide Field ◽  
Plasma Properties ◽  
X Ray

<p>The X-Ray Telescope (XRT) onboard the Hinode satellite has a specially designed Wolter type grazing-incidence (GI) optics with a paraboloid-hyperboloid mirror assembly to measure the solar coronal plasma of temperatures up to 10 MK with a resolution of about one arcsec. One of the main purposes of this scientific mission is to investigate the detailed mechanism of energy transfer processes from the photosphere to the upper coronal region leading to its heating and the solar wind acceleration. To theoretically model the three-dimensional coronal structures is sensitive to the values of plasma properties at the base of solar corona and thus requires beforehand accurate empirical description of those properties. Though the telescope has provided unprecedented observations of solar corona for more than a decade, due to a wide field of view of 34 x 34 arcmin covering the full Sun, the optical performance of the instrument gradually deteriorates as it goes away from the optical center. For this reason, the off-axis characteristics of Hinode/XRT should be examined with care in order to precisely interpret the coronal plasma properties near the solar limb area.</p><p>This presentation will explain the importance of accurate calibration of the optical characteristics, especially for the data taken in the off-axis region. Our previous study has shown that the scattered light caused by the XRT mirror surface roughness has a power-law distribution and also shows an energy dependence, with which the PSF profile from the core to the scattering wing has been completed. We will introduce in this study how the level of scattering wing can be determined quantitatively for each focal plane filter from in-flight data analysis. We have also evaluated the vignetting effect in Hinode/XRT by analyzing the 2D distribution of effective area in the field of view taken from MSFC/XRCF pre-launch experiment. It is revealed that, unlike the case of Yohkoh/SXT, the degree of offset of an optical center is not serious and thus shows little deviation from rotational symmetry. Also important is that the vignetting pattern in XRT shows an energy dependence, which has never been considered before for the analyses of XRT data. More interesting results on the calibration of Hinode/XRT scattered light and the correction of vignetting effect will be introduced and discussed thoroughly. </p>

Detailed Calibration of the Off-Axis Optical Characteristics for the X-Ray Telescope onboard Hinode

2021 ◽  
Author(s):  
Junho Shin ◽  
Ryouhei Kano ◽  
Takashi Sakurai ◽  
Yeon-Han Kim ◽  
Yong-Jae Moon
Keyword(s):  
Energy Dependence ◽  
Scattered Light ◽  
Grazing Incidence ◽  
Optical Characteristics ◽  
Optical Center ◽  
Power Law Distribution ◽  
X Ray ◽  
Scientific Mission ◽  
Astronomical Object ◽  
Axis Position

<p>The X-Ray Telescope (XRT) onboard the Hinode satellite has a specially designed Wolter type grazing-incidence (GI) optics with a paraboloid-hyperboloid mirror assembly to measure the solar coronal plasma of temperatures up to 10 MK with a resolution of about one arc sec. One of the main purposes of this scientific mission is to investigate the detailed mechanism of energy transfer processes from the photosphere to the upper coronal region leading to its heating and the solar wind acceleration. An astronomical telescope is in general designed such that the best-focused image of an object is achieved at or very close to the optical axis, and inevitably the optical performance deteriorates away from the on-axis position. The Sun is, however, a large astronomical object and thus targets near the limb of full-disk images are placed at the outskirt of the field of view. The design of a solar telescope should thus consider the uniformity of imaging quality over a wide FOV, and it is particularly so for X-ray telescopes whose targets can be in the corona high above the limb.</p><p> </p><p>We will explain in this presentation the importance of detailed calibration of the off-axis optical characteristics for Hinode/XRT. It have been revealed that the scattered light caused by the GI mirror surface has a power-law distribution and shows an energy dependence. We will also introduce the basic scheme of how the level of scattering wing is determined and connected to the core from the analysis of highly saturated in-flight data. Vignetting is another important optical characteristics for describing the telescope's performance, which reflects the ability to collect incoming light at different locations and photon energies. We have evaluated the vignetting effect in Hinode/XRT by analyzing the ground experimental data and found that the degree of vignetting varies linearly from the optical center and its pattern shows an energy dependence. Many interesting results on the calibration of Hinode/XRT optical characteristics will be introduced and discussed thoroughly. </p>

Synthetic Wavelength Holography: Snapshot Non-Line-of-Sight Imaging with High-Resolution and Wide Field of View

2020 ◽  
Author(s):  
Florian Willomitzer ◽  
Prasanna Rangarajan ◽  
Fengqiang Li ◽  
Muralidhar Balaji ◽  
Marc Christensen ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging System ◽  
Scattered Light ◽  
Field Of View ◽  
Line Of Sight ◽  
Wide Field ◽  
Navigation Systems ◽  
Small Probe ◽  
Wide Field Of View ◽  
Non Line Of Sight

Abstract The presence of a scattering medium in the imaging path between an object and an observer is known to severely limit the visual acuity of the imaging system. We present an approach to circumvent the deleterious effects of scattering, by exploiting spectral correlations in scattered wavefronts. Our Synthetic Wavelength Holography (SWH) method is able to recover a holographic representation of hidden targets with high resolution over a wide field of view. The complete object field is recorded in a snapshot-fashion, by monitoring the scattered light return in a small probe area. This unique combination of attributes opens up a plethora of new Non-Line-of-Sight imaging applications ranging from medical imaging and forensics, to early-warning navigation systems and reconnaissance. Adapting the findings of this work to other wave phenomena will help unlock a wider gamut of applications beyond those envisioned in this paper.

scholarly journals Wide-field Cameras for GRB Observations in X-rays and EUV

1995 ◽  
Vol 151 ◽  
pp. 431-434
Author(s):  
Eugene Moskalenko
Keyword(s):  
Time Scale ◽  
Field Of View ◽  
Time Variability ◽  
Wide Field ◽  
Main Task ◽  
X Rays ◽  
Interstellar Absorption ◽  
X Ray ◽  
Instrumental Approaches ◽  
Stationary Sources

Recent observations of the ASCA satellite resulted in the first identification of a GB source (Murakami et al. 1994). This success confirmed the importance of simultaneous observations in different wavelength bands for GB studies. Besides the ASCA results, there were several observations of GBs in X-ray band with the Ginga (Yoshida et al,.1989), V 78/1 (Laros et al. 1984) and other satellites. It became clear that GBs emit 4 - 8% of their energy in the 2 - 10 keV range. The main task now is to have an equipment which will be able to monitor the sky in X-rays in a mode similar to that of GRO observations, i.e. the telescope should have an all-sky field-of-view (FoV) and should work continuously.A telescope with these features but operating at soft X-ray energies may directly determine the GB distance scale, due to interstellar absorption of the photons with energies less than 2 keV, as was pointed out first by Schaefer (1993). Flaring sources similar to GBs in time scale may be found also in the EUV (hundreds of angstroms) with the help of very wide-field cameras. Of course each such device - in X-ray, soft X-ray and EUV bands - will discover many transient objects, flaring events, will study time variability of bright “stationary” sources etc. In this paper we describe several instrumental approaches in these fields.

scholarly journals Monochromatic X-Ray Imagers of the Sun Based on the Bragg Crystal Optics

2021 ◽  
Vol 8 ◽  
Author(s):  
Anton A. Reva ◽  
Sergey V. Kuzin ◽  
Alexey S. Kirichenko ◽  
Artem S. Ulyanov ◽  
Ivan P. Loboda ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Corona ◽  
Spectral Lines ◽  
Coronal Plasma ◽  
The Sun ◽  
Spectral Filter ◽  
Crystal Optics ◽  
X Ray ◽  
Hot Plasma ◽  
Wide Range

Investigations of solar activity require information about plasma in a wide range of temperatures. Generally, researchers require observations from telescopes producing monochromatic images of coronal plasma with cool, warm, and hot temperatures. Until now, monochromatic telescopic imaging has been made only in the Mg XII 8.42 Å line with the Mg XII spectroheliograph on board CORONAS-I, CORONAS-F, and CORONAS-PHOTON satellites. The Mg XII spectroheliograph used Bragg crystal optics. Its design is based on two main principles: (1) to select the working wavelength and the crystal in such a way that reflection occurs at small incident angles; (2) to use the aperture of the mirror as a spectral filter. We believe that these design principles can be applied to other spectral lines. In this article, we will review the design of the Mg XII spectroheliograph and present our thoughts on how to apply these principles to the Si XIV 6.18 Å and Si XIII 6.65 Å lines. A combination of the monochromatic Mg XII 8.42 Å, Si XIV 6.18 Å, and Si XIII 6.65 Å images will help us to study the dynamics of the hot plasma in the solar corona.

scholarly journals A Search for the Signature of the Diffuse Soft X-ray Background in the ROSAT Wide-Field Camera All-Sky Survey

1996 ◽  
Vol 152 ◽  
pp. 289-293
Author(s):  
R.G. West ◽  
R. Willingale ◽  
J.P. Pye ◽  
T.J. Sumner
Keyword(s):  
Charged Particles ◽  
Field Of View ◽  
Wide Field ◽  
Galactic Latitude ◽  
The Sun ◽  
X Ray ◽  
Cosmic Background ◽  
Sky Survey ◽  
Cosmic Abundance ◽  
X Ray Background

We present the results of an attempt to locate the signature of the diffuse soft X-ray background in the ROSAT Wide-Field Camera (WFC) all-sky survey. After removal of non-cosmic background sources (eg. energetic charged particles), the field-of-view integrated count rate in the WFC S1a filter (90–185 eV) shows no consistent variation with Galactic latitude or longitude. We place limits on the signal from the soft X-ray background (SXRB) in the WFC, and show that these limits conflict with the observations of the Wisconsin Sky Survey if the SXRB in this energy range is assumed to be produced by a thermal plasma of cosmic abundance and a temperature T ~ 106 K within d ~ 100 pc of the Sun.

scholarly journals A Rocket-Borne X-Ray Spectrometer/Monochromator System for Mapping the Solar Corona

1971 ◽  
Vol 41 ◽  
pp. 181-181
Author(s):  
L. W. Acton ◽  
R. C. Catura ◽  
J. L. Culhane ◽  
A. J. Meyerott
Keyword(s):  
Spatial Distribution ◽  
Solar Corona ◽  
Proportional Counter ◽  
Line Emission ◽  
Field Of View ◽  
The Sun ◽  
X Ray ◽  
Rocket Flight

A rocket payload is being prepared for the purpose of examining the spatial distribution of line emission from two important ions, Ovii and Neix, in the solar corona. The payload will contain the following integrated set of instruments.(1) A pair of X-ray spectrometers utilizing KAP crystals of approximately 100 cm2 area.(2) An optical aspect camera with a 1 Å bandpass H-α filter to measure the location of the field of view of the X-ray systems on the sun through out the rocket flight.(3) A collimated proportional counter spectrometer operating in the 3 to 15 keV range.

Wide-field-of-view phase-contrast imaging of nanostructures with a comparatively large polychromatic soft x-ray plasma source

2009 ◽  
Vol 34 (21) ◽  
pp. 3268 ◽  
Author(s):  
S. V. Gasilov ◽  
A. Ya. Faenov ◽  
T. A. Pikuz ◽  
Y. Fukuda ◽  
M. Kando ◽  
...  
Keyword(s):  
Phase Contrast ◽  
Plasma Source ◽  
Field Of View ◽  
Phase Contrast Imaging ◽  
Wide Field ◽  
Contrast Imaging ◽  
X Ray ◽  
Wide Field Of View
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