Solar X-ray Spectrometer (Soxs) Mission on Board GSAT2 Indian Spacecraft: The Low-Energy Payload     

Rajmal Jain  Hemant Dave  A. B. Shah  N. M. Vadher  Vishal M. Shah  G. P. Ubale  K. S. B. Manian  Chirag M. Solanki  K. J. Shah  Sumit Kumar  S. L. Kayasth  V. D. Patel  Jayshree J. Trivedi  M. R. Deshpande 《Solar physics》2005,227(1):89-122

The first space-borne solar astronomy experiment of India, namely Solar X-ray Spectrometer (SOXS), was successfully launched on 08 May 2003 on board geostationary satellite GSAT-2 of India. The SOXS is composed of two independent payloads, viz. SOXS Low-Energy Detector (SLD) Payload and SOXS High-Energy Detector (SHD) Payload. The SOXS aims to study the full-disk integrated X-ray emission in the energy range from 4 keV to 10 MeV. In this paper we present the first report on the SLD instrumentation and its in-orbit performance. The SLD payload was designed and developed at the Physical Research Laboratory in collaboration with various centers of Indian Space Research Organisation (ISRO). The basic scientific aim of the SLD payload is to study solar flares in the energy range from 4 to 60 keV with high spectral and temporal resolution. To meet these requirements, the SLD payload employs state-of-the-art solid state detectors, the first time for a solar astronomy experiment, viz. Si PIN (4 –25 keV), and cadmium–zinc–telluride (4 –60 keV). With their superb high-energy resolution characteristics, SLD can observe iron and iron–nickel complex lines that are visible only during solar flares. In view of its 3.4 FOV, the detector package is mounted on a Sun Aspect System, for the first time, to get uninterrupted observations in a geostationary orbit. The SLD payload configuration, its in-flight operation, and the response of the detectors are presented. We also present the first observations of solar flares made by the SLD payload and briefly describe their temporal and spectral mode results.  相似文献   

Radio and X-ray burst from PSR 0950+08     

M. R. Deshpande  Hari Om Vats  Harish Chandra  P. Janardhan  A. D. Bobra  G. D. Vyas 《Astrophysics and Space Science》1994,218(2):249-265

This article describes in detail a burst from PSR 0950+08 on July 29, 1992. This event was observed by two radio telescopes (separated by ~ 200 km) operating at 103 MHz. There exists a very convincing indirect evidence that at the same time the pulsar also emitted large X-ray flux. The X-ray flux during the event compares with that during a solar X-ray flare. During the event the Sun was extraordinarily quiet as the solar X-ray flux 3 · 10^–7 W/m² only was observed. The cause for the burst is quite unknown and may be complex. However, a possibility of accretion of a comet-like object by pulsar may provide reasonable explanation of the observations. These results open some interesting questions about the pulsar physics.  相似文献   

Effect of carbon dioxide sequestration on the mechanical properties of Deccan basalt     

Debanjan Guha Roy  Vikram Vishal  Trilok Nath Singh 《Environmental Earth Sciences》2016,75(9):771

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Synoptic variation of stable isotopes in precipitation and ground level vapour in a humid tropical region,Kerala, India     

Ahmed Shahul Hameed  Thoppil Ramakrishnan Resmi  Mohan Praveenbabu  Maroli Sudheesh  Rajendrakumar Dattatraya Deshpande 《Environmental Earth Sciences》2016,75(21):1412

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A possible detection of radio pulses from Geminga at 103 MHz     

Hari Om Vats  Ashok K. Singal  M. R. Deshpande  K. N. Iyer  Rupal Oza  Chhaya R. Shah  S. Doshi 《Monthly notices of the Royal Astronomical Society》1999,302(4):L65-L67

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Did the Harappan settlement of Dholavira (India) collapse during the onset of Meghalayan stage drought?     

Torsa Sengupta  Arati Deshpande Mukherjee  Ravi Bhushan  F. Ram  M. K. Bera  Harsh Raj  Ankur J. Dabhi  R. S. Bisht  Y. S. Rawat  S. K. Bhattacharya  Navin Juyal  Anindya Sarkar 《第四纪科学杂志》2020,35(3):382-395

Radiocarbon dating of archaeological carbonates from seven cultural stages of Dholavira, Great Rann of Kachchh (GRK), the largest excavated Harappan settlement in India, suggests the beginning of occupation at ~5500 years BP (pre-Harappan), and continuation until ~3800 years BP (early part of the Late Harappan period). The settlement rapidly expanded under favourable monsoonal climate conditions when architectural elements such as the Citadel, Bailey, Lower and Middle Town were added between the Early and mid-Mature Harappan periods. Abundant local mangroves grew around the GRK sustaining prolific populations of the edible gastropod Terebralia palustris. Oxygen isotope (δ¹⁸O) sclerochronology of Early Harappan gastropod shell suggests seasonal mixing of some depleted (δ¹⁸O ~ −12‰) river water in summer/monsoon months (through ancient Saraswati and/or Indus distributary channels) with seawater that periodically inundated the GRK. Evaporation from this semi-enclosed water body during the non-monsoon months enriched the δ¹⁸O of water/shell carbonates. The humid fluvial landscape possibly changed due to a catastrophic drought driving the final collapse of the settlement of Dholavira exactly at the onset of the Meghalayan (Late Holocene) stage (~4300–4100 years BP ). Indeed, Dholavira presents a classic case for understanding how climate change can increase future drought risk as predicted by the IPCC working group. Copyright © 2019 John Wiley & Sons, Ltd.  相似文献   

The Effect of Contaminated Prey on Feeding,Activity, and Growth of Young-of-the-Year Bluefish, <Emphasis Type="Italic">Pomatomus saltatrix</Emphasis>, in the Laboratory     

Allison C. Candelmo  Ashok Deshpande  Bruce Dockum  Peddrick Weis  Judith S. Weis 《Estuaries and Coasts》2010,33(4):1025-1038

Young-of-the-year (YOY) bluefish, Pomatomus saltatrix, reside in some contaminated estuaries of the mid-Atlantic bight during their early life history, and as a result of this exposure, they may bioaccumulate high levels of contaminants, including polychlorinated biphenyls (PCBs), pesticides, and methyl mercury. Young-of-the-year bluefish from the Tuckerton, NJ, area of Great Bay (TK) were fed daily in a laboratory with common prey fish, menhaden, and mummichog from two sites: TK (reference) or Hackensack River (HR) (contaminated). Bluefish fed HR prey and the HR prey themselves had significantly elevated concentrations of PCBs, pesticides, and total mercury compared to TK counterparts. The bluefish fed contaminated prey for 4 months displayed significantly reduced feeding, spontaneous activity, and growth compared to the bluefish fed TK prey. Alterations of bluefish behavior and growth from exposure to contaminants may have detrimental effects on migration, overwinter survival, and recruitment success.  相似文献   

Archaeological Evidence for Modern Coastal Uplift at Diu,Saurashtra Peninsula,India     

Mikls Kzmr  Nilesh Bhatt  Vishal Ukey  Siddharth Prizomwala  Danko Taboro&#x;i  Balzs Szkely 《Geoarchaeology》2016,31(5):376-387

There is a tank hewn into coastal Pleistocene limestone near Diu city on the Saurashtra Peninsula of western India. Site survey and a review of similar structures worldwide provide evidence that this tank could have been used for holding fish or Murex snails. The approximately 5 × 5 m tank is connected to the sea by a 1‐m‐deep canal; today it would be impossible to use the tank, given that not even the high spring tides can fill it. It is suggested that the Diu coast was uplifted by ∼0.5 m after the tank was hewn in the coastal platform. Since that time, the carved surfaces have been modified by coastal karst dissolution and have developed deep gouge marks. Uplift of the Diu coast raises the possibility of a major seismic event in Diu during the latter part of the last millennium.  相似文献   

Hydrograph separation and precipitation source identification using stable water isotopes and conductivity: River Ganga at Himalayan foothills   总被引：3，自引：0，他引：3  

A. S. Maurya  Miral Shah  R. D. Deshpande  R. M. Bhardwaj  A. Prasad  S. K. Gupta 《水文研究》2011,25(10):1521-1530

The observed retreat of several Himalayan glaciers and snow packs is a cause of concern for the huge population in southern Asia that is dependent on the glacial‐fed rivers emanating from Himalayas. There is considerable uncertainty about how cryospheric recession in the Himalayan region will respond to climate change, and how the water resource availability will be affected. As a first step towards quantifying the contribution of glacier‐melt water, hydrograph separation of River Ganga at Rishikesh into its constituent components, namely (i) surface runoff, (ii) glacial ice‐melt and (iii) groundwater discharge has been done in this paper. A three‐component mixing model has been employed using the values of δ¹⁸O and electrical conductivity (EC) of the river water, and its constituents, to estimate the time‐varying relative fraction of each component. The relative fraction of the surface runoff peaks (70–90%) during winter, due to the near‐zero contribution of glacial ice‐melt, essentially represents the melting of surface snow from the catchment. The contribution of glacial ice‐melt to the stream discharge peaks during summer and monsoon reaches a maximum value of ～40% with an average of 32%. The fraction of groundwater discharge varies within a narrow range (15 ± 5%) throughout the year. On the basis of the variation in the d‐excess values of river water, it is also suggested that the snow‐melt and ice‐melt component has a significant fraction derived from winter precipitation with moisture source from mid‐latitude westerlies (also known as western disturbances). Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Study of microflares through soxs mission     

Rajmal Jain  Vishal Joshi  Yoichiro Hanaoka  T. Sakurai  Nipa Upadhyay 《Journal of Astrophysics and Astronomy》2006,27(2-3):339-346

We present a study of 10 microflares observed in 4–30 keV by SOXS mission simultaneously with Hα observations made at NAOJ, Japan during the interval between February and August 2004. The X-ray and Hα light curves showed that the lifetime of microflares varies between 4 and 25 min. We found that the X-ray emission in all microflares under study in the dynamic energy range of 4–30 keV can be fitted by thermal plus non-thermal components. The thermal spectrum appeared to start from almost 4 keV, low level discriminator (LLD) of both Si and CZT detectors, however it ends below 8 keV. We also observed the Fe line complex features at 6.7 keV in some microflares and attempted to fit this line by isothermal temperature assumption. The temperature of isothermal plasma of microflares varies in the range between 8.6 and 10.1 MK while emission measure between 0.5 and 2x10⁴9 cm^-3. Non-thermal (NT) emission appeared in the energy range 7–15 keV with exponent -6.8 ≤γ≤-4.8. Our study of microflares that had occurred on 25 February 2004 showed that sometimes a given active region produces recurrent microflare activity of a similar nature. We concluded from X-ray and simultaneous Hα observations that the microflares are perhaps the result of the interaction of low lying loops. It appears that the electrons that accelerated during reconnection heat the ambient coronal plasma as well as interact with material while moving down along the loops and thereby produce Hα bright kernels.  相似文献