Broad-band, high-resolution photograph of the solar corona February 16, 1980

Solar Physics ◽  
1983 ◽  
Vol 85 (2) ◽  
pp. 235-236
Author(s):  
K. K. Scaria
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Broad Band ◽  
Resolution Photograph

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

scholarly journals Joint Discussion 4 UV astronomy: stars from birth to death

2006 ◽  
Vol 2 (14) ◽  
pp. 169-194
Author(s):  
Ana I. Gómez de Castro ◽  
Martin A. Barstow
Keyword(s):  
High Resolution ◽  
Uv Spectroscopy ◽  
Broad Band ◽  
Mission Planning ◽  
High Resolution Spectroscopy ◽  
Low Resolution ◽  
Short Term ◽  
Uv Astronomy ◽  
Optical Telescope ◽  
The Moment

AbstractThe scientific program is presented as well a the abstracts of the contributions. An extended account is published in “The Ultraviolet Universe: stars from birth to death” (Ed. Gómez de Castro) published by the Editorial Complutense de Madrid (UCM), that can be accessed by electronic format through the website of the Network for UV Astronomy (www.ucm.es/info/nuva).There are five telescopes currently in orbit that have a UV capability of some description. At the moment, only FUSE provides any medium- to high-resolution spectroscopic capability. GALEX, the XMM UV-Optical Telescope (UVOT) and the Swift. UVOT mainly delivers broad-band imaging, but with some low-resolution spectroscopy using grisms. The primary UV spectroscopic capability of HST was lost when the Space Telescope Imaging Spectrograph failed in 2004, but UV imaging is still available with the HST-WFPC2 and HST-ACS instruments.With the expected limited lifetime of sl FUSE, UV spectroscopy will be effectively unavailable in the short-term future. Even if a servicing mission of HST does go ahead, to install COS and repair STIS, the availability of high-resolution spectroscopy well into the next decade will not have been addressed. Therefore, it is important to develop new missions to complement and follow on from the legacy of FUSE and HST, as well as the smaller imaging/low resolution spectroscopy facilities. This contribution presents an outline of the UV projects, some of which are already approved for flight, while others are still at the proposal/study stage of their development.This contribution outlines the main results from Joint Discussion 04 held during the IAU General Assembly in Prague, August 2006, concerning the rationale behind the needs of the astronomical community, in particular the stellar astrophysics community, for new UV instrumentation. Recent results from UV observations were presented and future science goals were laid out. These goals will lay the framework for future mission planning.

Broad band and high resolution scanning spectrum calibration technology

2020 ◽  
Vol 13 (2) ◽  
pp. 249-257
Author(s):  
迟明波 CHI Ming-bo ◽  
韩欣欣 HAN Xin-xin ◽  
徐 阳 XU Yang ◽  
舒风风 SHU Feng-feng ◽  
吴一辉 WU Yi-hui
Keyword(s):  
High Resolution ◽  
Broad Band ◽  
Spectrum Calibration

scholarly journals Ultraviolet properties of the symbiotic stars

1982 ◽  
Vol 70 ◽  
pp. 103-113
Author(s):  
Mark H. Slovak ◽  
David L. Lambert
Keyword(s):  
High Resolution ◽  
Broad Band ◽  
Symbiotic Star ◽  
Symbiotic Stars ◽  
Interim Report

Prior to the launch of the IDE satellite in early 1978, the only symbiotic star previously detected in the ultraviolet by earlier UV satellites, such as the 0A0-2, TD-1 and ANS experiments, was AG Pegasi = HD 207757 (Gallager et al. 1979). These broad-band observations indicated that the symbiotics as a class may show a significant ultraviolet flux and thus they became natural candidates for a survey with the IUE satellite. The following is an interim report on a survey of the symbiotics, both at low and, for AG Pegasi and CH Cygni, at high resolution.

An EUV imaging spectrograph for high-resolution observations of the solar corona

Solar Physics ◽  
1992 ◽  
Vol 137 (1) ◽  
pp. 87-104 ◽  
Author(s):  
Werner M. Neupert ◽  
Gabriel L. Epstein ◽  
Roger J. Thomas ◽  
William T. Thompson
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Imaging Spectrograph ◽  
Euv Imaging

High resolution mapping of the magnetic field of the solar corona

Solar Physics ◽  
1977 ◽  
Vol 51 (2) ◽  
pp. 345-375 ◽  
Author(s):  
Martin D. Altschuler ◽  
Randolph H. Levine ◽  
Michael Stix ◽  
John Harvey
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Solar Corona ◽  
High Resolution Mapping ◽  
Resolution Mapping ◽  
The Magnetic Field

scholarly journals The development and initial field trials of a new high frequency seismic vibrator

1989 ◽  
Vol 20 (2) ◽  
pp. 163
Author(s):  
D.B. Stewart ◽  
M.R. Seman
Keyword(s):  
High Resolution ◽  
High Frequency ◽  
Broad Band ◽  
Seismic Source ◽  
Field Trials ◽  
Electronic Control ◽  
Initial Field ◽  
Frequency Wave ◽  
The Cost ◽  
Zero Phase

The cost of shot hole drilling is often more expensive than using vibratory energy sources in high resolution seismic surveying. However, such costs are often accepted since conventional vibrators cannot always provide the extreme imaging capacity required in high resolution work. Conventional seismic vibrators sweep in a range from 5 Hz to 250 Hz ? the range of which is limited by the vibrator. The impulse train of the high resolution wacker used by the MiniSOSIE1 system is also band limited, causing a reduction in imaging resolution. The ideal solution is to sweep a broad range of frequencies from the lower seismic range to as high as 500 Hz. This could offer a cost effective solution to the acquisition of broad band high resolution data. In high resolution seismic profiling, explosives are commonly used as the source. Small charges below the weathered layer produce the highest frequency content (Ziolkowski and Lerwill, 1979). Unfortunately, the cost of drilling shot holes is a major component of the survey costs. For oil exploration in Australia/New Zealand, dynamite surveys average 43% more than Vibroseis2 surveys in dollars per kilometre (Montgomery, 1987), despite more hardware being required for Vibroseis recording.The MiniSOSIE system is also used for some high resolution surveys, because it is relatively cheap. However, this does not achieve equivalent results to small explosives. It will give worse results as the soil becomes softer, as the rebound from an impact takes longer, and hence the wavelet is broader.An alternative to these sources is the hydraulic powered vibrator, which has sometimes been used for high resolution coal work in Europe. With vibrators, the spectrum is controllable within certain limits. The Vibroseis system can also produce zero phase wavelets, if used properly with its controllable frequency wave-train sweep; and with repeatable multiple sweeps this results in enhancement of signal to noise ratio together with the promise of the highest frequency returns. Zero phase wavelets have slightly better resolution than the same bandwidth minimum phase wavelets as produced by impulsive sources. The breadth (t) of a zero phase Klauder wavelet with a boxcar spectrum can be predicted from the sweep start (fS) and end (fE) frequencies by the approximation: [see full text for equation]. By sweeping 50 to 500 Hz, a wavelet 1.8 ms wide should result, which is the resolution required to locate faults with a throw of less than two metres. In practice, a wider wavelet may be obtained, due to absorption of the high frequency energy. The Vibrator Seismic Source (VSS) is presented here in its first application of this new hydraulic powered vibratory source, which operates under different mechanical and electronic control than used heretofore by conventional vibratory sources. The VSS has been developed continuously since 1980 when an initial grant was received from NERDDC. During the intervening years till 1987, two more grants were received (Stewart, 1988). A recent further NERDDC grant was received in 1988 jointly by ACIRL, Curtin University and University College ADFA for areal coal seam mapping by three-dimensional seismic reflection surveying, with an emphasis on high resolution imaging of faults. The novelty of the VSS lies in the use of a single flow path for hydraulic oil through the flow stage of a Servo Popper Valve (SPV) (Stewart, 1986). This powers the vibrator by application of the oil to only one side of a piston in the linear actuator which produces the forced output of the vibrator on the surface of the earth. Conventional vibrators use a spool valve to alternately reverse the flow of oil into opposite chambers of a double acting cylinder. Hence the VSS has a fluid power advantage over conventional vibrators and this is evident by better performance at the higher frequencies. The VSS can sweep typically from 50 Hz to 500 Hz, and was initially field tested as a high resolution energy source. Innovations in both mechanical and electronic control systems are presented and results of the initial field trials of the VSS are compared to explosive seismic source results. 1Trade Mark of CGG 2Trade Mark of Conoco

scholarly journals Spectropolarimetric determination of circumstellar disc inclinations

1994 ◽  
Vol 162 ◽  
pp. 230-231
Author(s):  
Kenneth Wood
Keyword(s):  
High Resolution ◽  
Velocity Structure ◽  
Broad Band ◽  
Spectral Shape ◽  
Wavelength Shift ◽  
Model Parameters ◽  
Finite Width ◽  
Structure Model ◽  
Diagnostic Potential

Inference of the density and velocity structure of rotating/expanding circumstellar discs/winds is of considerable interest in the understanding of stellar mass loss. High resolution line spectropolarimetry creates the possibility of diagnosing such envelope structure much more fully than broad band polarimetry or high resolution spectrometry alone since each element of the scattered spectropolarimetric profile picks out the element of the envelope with the appropriate Doppler shift and provides orientation information on it. This problem has been formulated in detail by Wood, et al (1993) for scattering of a finite width line in a flattened envelope – the spectral shape of the scattered Stokes fluxes being determined by isowavelength–shift contours or surfaces which give the relative wavelength shift of the scattered radiation at different regions in the disc. It was also shown how, in the case of a narrow stellar line scattered in a rotating or expanding flat disc with a simply parametrised density and velocity structure (ignoring the smearing effect of electron thermal motions), it is possible to infer the system inclination and structure model parameters from the resulting spectropolarimetric line profile. This poster presents a method for determining the disc inclination from analysis of the scattered profiles – a parameter which cannot be determined uniquely from spectrometry alone – and thus illustrates the powerful diagnostic potential of high resolution line spectropolarimetry.

scholarly journals Along-strike variation in slab geometry at the southern Mariana subduction zone revealed by seismicity through ocean bottom seismic experiments

2019 ◽  
Vol 218 (3) ◽  
pp. 2122-2135 ◽  
Author(s):  
Gaohua Zhu ◽  
Hongfeng Yang ◽  
Jian Lin ◽  
Zhiyuan Zhou ◽  
Min Xu ◽  
...  
Keyword(s):  
High Resolution ◽  
Subduction Zone ◽  
Matched Filter ◽  
Near Field ◽  
Broad Band ◽  
Velocity Model ◽  
Ocean Bottom ◽  
Slab Geometry ◽  
Seismicity Distribution ◽  
Geodynamic Processes

SUMMARYWe have conducted the first passive Ocean Bottom Seismograph (OBS) experiment near the Challenger Deep at the southernmost Mariana subduction zone by deploying and recovering an array of 6 broad-band OBSs during December 2016–June 2017. The obtained passive-source seismic records provide the first-ever near-field seismic observations in the southernmost Mariana subduction zone. We first correct clock errors of the OBS recordings based on both teleseismic waveforms and ambient noise cross-correlation. We then perform matched filter earthquake detection using 53 template events in the catalogue of the US Geological Survey and find >7000 local earthquakes during the 6-month OBS deployment period. Results of the two independent approaches show that the maximum clock drifting was ∼2 s on one instrument (OBS PA01), while the rest of OBS waveforms had negligible time drifting. After timing correction, we locate the detected earthquakes using a newly refined local velocity model that was derived from a companion active source experiment in the same region. In total, 2004 earthquakes are located with relatively high resolution. Furthermore, we calibrate the magnitudes of the detected earthquakes by measuring the relative amplitudes to their nearest relocated templates on all OBSs and acquire a high-resolution local earthquake catalogue. The magnitudes of earthquakes in our new catalogue range from 1.1 to 5.6. The earthquakes span over the Southwest Mariana rift, the megathrust interface, forearc and outer-rise regions. While most earthquakes are shallow, depths of the slab earthquakes increase from ∼100 to ∼240 km from west to east towards Guam. We also delineate the subducting interface from seismicity distribution and find an increasing trend in dip angles from west to east. The observed along-strike variation in slab dip angles and its downdip extents provide new constraints on geodynamic processes of the southernmost Mariana subduction zone.

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