039082   HASHEMI M (Geology Dep, Payame Noor Univ, Iran, Email: economic.geology@yahoo.com) : Remote sensing and airborne geophysics studies for uranium and thorium exploration in Zahedan area (Southeastern Iran). Indian J Geo-Mar Sci 2020, 49(2), 201-6.

The study area is located in Nehbandan-Khash zone according to the structural classification of Iran. The outcrops of this area are mainly composed of Cenozoic and Quaternary units. The structure of the area, under the influence of faults and folding, has a trend from north-northwest to south-southeast. Airborne data of radiometric was collected in the study area. In the exploration area of Zahedan, after processing and statistical analysis airborne radiometric data and preparing the map of the radioactive elements with the same intensity, the anomaly ranges were determined. For this purpose, two Ordinary Kriging and inverse distance squared technique were used to estimate the data. The trend of these radioactive elementanomalies in the area was the general northwest-southeast trend, as identified in the maps. These anomalies of the radioactive elements are found in the Oligo-Miocene granodiorites units. Three anomaly ranges are located in the north eastern corner of the sheet, which are proposed as valuable anomalies for continuing exploratory study.

9 illus, 4 tables, 11 ref

026269   DESWAL M, LAURA J S (Environmental Sciences Dep, Maharshi Dayanand Univ, Rohtak (Haryana), Email: meenadeswal02@gmail.com) : GIS based modeling using analytic hierarchy process (AHP) for optimization of landfill site selection of Rohtak city, Haryana (India). J Appl Nat Sci 2018, 10(2), 633 - 42.

Landfills are the most common method for the disposal of municipal solid waste the world over, as well as in India due to their low technical and economic requirements. The selection of an appropriate site for the establishment of a landfill is a complex process because it must combine social, environmental and technical parameters. The scientific selection of landfill site is based on several diverse criteria (Land Use and Land Cover, ground water table depth, soil permeability, surface water, roads distance, slop etc) and regulations. The study presents the selection of a site for the establishment of a landfill based on several criteria using geographic information system (GIS) based site suitability modeling and analytical hierarchy process (AHP). Site suitability modeling was implemented using Boolean and Index overlay models. Each criterion and sub criteria was evaluated with the aid of AHP to assign a relative weightage in the index overlay model. Rules and criteria’s set by Central Pollution Control Board (CPCB) and Central Public Health and Environmental Engineering Organisation (CPHEEO) were implemented through Boolean model. The combination of the results of the two models generated a map with several suitable sites. Further selection was done on basis of the size requirement of the site, to handle Municipal solid waste (MSW) for next ten years. Two sites having the maximum suitability and also fulfilling the size requirement were shortlisted. Final selection from the two sites was done by a field survey of the sites. Finally the site B was selected on the basis of field survey which revealed it being better on account of certain factors discussed and social acceptability.

6 illus, 3 tables, 50 ref

026270   NIGAM B, SINGH P R, CHAMADIA P K, SAXENA A K, TIWARI C M (Govt. Autonomous P. G. Coll, Satna, Email: bharti.nigam@gmail.com) : Effect of solar activity on earth's climate during solar cycles 23 and 24. Asian J Exp Sci 2018, 32(1), 11-5.

The Sun's energy that drives the weather system might connect the Earth's climate changes for the period 1996-2016. The Sun's activity could explain the global warming in the 21st century. The Sun-Earth connection has to influence thermosphere, atmosphere, and ionosphere. The effects of the solar variability are evident in a variety of physical and chemical process in the upper atmosphere. In the present study, we have found a global surface temperature anomalies change (a factor ~1.29 ⁰C) from 1996 to 2016. We have found a positive correlation between total solar irradiance (TSI) with Kp-Index, AE- Index and global surface Temperature anomalies (GTA) during solar cycles 23-24. We have found that the effect of these parameters in the Earth's climate is very minimal.

5 illus, 15 ref

029947   NAZARI-GOLSHAN A (Physics Dep, Shahed Univ, Tehran, Iran, Email: nazarigolshan@yahoo.com) : Investigation of cylindrical shock waves in dusty plasma. Indian J Phys 2018, 92(12), 1643–50.

Electronegative dusty plasma composed of Boltzmann electrons, Boltzmann negative ions, inertial positive ions and charge fluctuating dust has been considered. The fractional modified Burgers’ (FMB) equation, which is derived using Euler–Lagrange variational technique, is analytically obtained and solved for studying the cylindrical geometry effect on the propagation of the dust ion acoustic shock wave. The Laplace homotopy perturbation method, the so-called LHPM is applied to solve the FMB equation. The effect of the fractional parameter, positive ion number density at equilibrium, the number of equilibrium electrons residing on the dust grain surface and shock velocity on the behavior of the shock waves in the dusty plasma has been investigated.

6 illus, 63 ref

029948   SKEIVALAS J, RADIS D, SLIKAS D (Geodesy and Cadastr Dep, Vilnius Gediminas Technical Univ, 10223 Vilnius, Lithuania, Email: dominykas.slikas@vgtu.lt) : Identification analysis of digital images of black holes of Centaurus A galaxy. Indian J Phys 2018, 92(12), 1495–501.

This article analyses digital images from the black hole map of Centaurus A galaxy using autovariance and covariance functions. This map was created based on data collected with APEX and Max-Planck/ESO radiotelescopes in Chile (Nemiroff and Bonnell in Astronomy picture of the day, 2011. https://apod.nasa.gov/apod/ap110531.html). Crosscovariance function estimates for two digital images or autocovariance function for individual images are calculated with random functions based on digital images’ pixels in vector form. Pixel vectors are estimated by emitting arrays of digital images’ pixels along according vectors. When the scale of the digital image shifts, the frequency of individual pixels’ colors remains constant, therefore shifting scales do not affect calculations for const and covariance functions. An RGB color spectrum was used for identification of images. The effect of composites of the RGB spectrum, and of color tensors, on estimates of covariance functions in digital images was assessed as well. The identity of digital images is evaluated by the change of correlation coefficients in the diapason of according values as determined using Matlab software.

12 illus, 20 ref

027516   NAGARAJA K, KUMAR B P, CHAKRAVARTY S C (Physics Dep, Bangalore Univ, Bengaluru-560 056, Email: kamsalinagaraj@bub.ernet.in) : X-ray flares and coronal mass ejections (CMEs) during very quiet solar activity conditions of 2009. Indian J Pure Appl Phys 2018, 56(8), 621-3.

Solar flares (SFs) are sudden brightening observed over the sun’s surface which is associated with a large energy release. Flares with burst of X-ray emission are normally followed by a mass ejection of electrons and ions from the solar atmosphere called coronal mass ejections (CMEs). There is an evidence that solar magnetic field can change its configuration through reconnection and release energy, accelerating solar plasma causing SFs and CMEs. This study examines the SFs/CMEs data from SOHO and GOES satellites during the very low solar activity year of 2009 and moderately high solar activity of 2002. The results indicate that certain modifications in the existing mechanisms of generating SFs/CMEs would be necessary for  developing more realistic forecast models affecting the space weather conditions.

2 illus, 4 ref

027517   VEDAVATHI P, DODDAMANI V H (Physics Dep, Bangalore Univ, Bangalore-560 056, Email: drvkdmani@gmail.com) : Long ultra violet monitoring IUE observation of MRK 478. Indian J Pure Appl Phys 2018, 56(8), 595-9.

Our universe comprises of many different kinds of objects such as planets, comets, asteroids, minor bodies, stars, galaxies, clusters of galaxies and super cluster of galaxies with their sizes and masses spread over several magnitudes. Amongst them, galaxies are considered as the building blocks of the universe in its large-scale structure perspective. Largely our universe consists of so-called “normal galaxies”, the bolometric luminosity of which is the sum of the luminosity of the constituent stars. The stars generate energy through nuclear fusion reactions. In sharp contrast, a small fraction ($\approx$ 1-10 %) of all these normal galaxies are distinguished by their overwhelmingly bright compact nuclei, which emits copious amount of radiation. These highly luminous (L_Bol > 10⁴² erg/s) galaxies are called as “active galaxies” or “active galactic nuclei” (AGNs). International ultraviolet satellite (IUE) launched in the year 1978 has made low resolution (~ 6-8 Å) UV spectroscopic observations of about 500 active galaxies until September, 1996 and has enabled us to understand the UV spectral properties. In this paper, we present the results of our variability studies of a narrow line Seyfert 1 galaxy MRK 478. We have found small amplitude continuum flux variability for observations spread over nearly 17 years. The amplitude of variability at shorter wavelengths is found to be higher than the amplitude at longer wavelengths for nearly simultaneous observations, consistent with the predictions of general “photoionization models” of active galaxies.

4 illus, 2 tables, 11 ref

027515   ENNAJI W, BARAKAT A, BAGHDADI M E, OUMENSKOU H, AADRAOUI M, KARROUM L A, HILALI A (Sultan Moulay Slimane Univ, Beni-Mellal, Morocco, Email: a.barakat@usms.ma) : GIS-based multi-criteria land suitability analysis for sustainable agriculture in the northeast area of Tadla plain (Morocco). J Earth Syst Sci 2018, 127(6), 79.

Assessment of soil suitability for sustainable intensive agriculture is an appropriate tool to select the land suitable for agricultural production with the least economic and environmental costs. This study was conducted to evaluate the agricultural soil quality in the northeast area of Tadla plain (Morocco) using geographic information system (GIS) and analytical hierarchy process (AHP). Six soil quality indicators, i.e., pH, organic carbon, cation exchange capacity, texture, salinity and slope were considered and performed in 60 subsurface soil samples. AHP method was utilized to identify the weight of each indicator from the pairwise comparison matrix. The weighted sum overlay analysis was then used to generate the soil quality map in a GIS environment, by overlaying both indicator weights and subindicator weights. The studied area was classified into four soil quality categories, i.e., poor, medium, good, and excellent, the percentage of each category is 1.12, 20.98, 61.07 and 16.83 %, respectively. The results indicated that 1.12 % of the study area has poor suitability for sustainable intensive agriculture due to their unsuitable texture and low salinity, while about 77 % of cultivated soils are adapted to agricultural production. The above results could be useful for the management of agricultural activity.

9 illus, 5 tables, 44 ref

027514   ARYA A S, RAJASEKHAR R P, SUR K, KRISHNA B G, SURESH K, SRINIVASAN T P, IYER K V, CHAUHAN P, AJAI, KUMAR A S K, PANDEY A D, KHARE A, VERMA P K (Indian Space Research Organisation, Ahmedabad- 380 015, Email: rajasekhar@sac.isro.gov.in) : Morphometric and rheological study of lunar domes of Marius Hills volcanic complex region using Chandrayaan-1 and recent datasets. J Earth Syst Sci 2018, 127(5), 70.

Marius Hills volcanic complex is one of the most important regions on the lunar surface having an abundant number of volcanic features like domes and cones. Systematic mapping of 106 domes/cones in the Marius Hills region was carried out in this study using high-resolution orthoimage and digital elevation models of Chandrayaan-1 and Kaguya missions. Various morphometric parameters like diameter, height, volume, flank slope, circularity index and form factor are derived for all the mapped domes. The rheological parameters, such as viscosity and eruption rate are estimated for isolated domes and cones superimposed over low domes. The morphometric and rheological properties of these domes are comparable to those located in the area near to Hortensius crater and other mare regions. Surface ages derived for a selected region in NW portion of the Marius Hills volcanic complex using crater size frequency distribution technique yields ages of 2.98 and 1.91 Ga. It suggests that the domes in this region formed at about 2.98 Ga ago, and then, the younger mare basalts likely embayed this region about 1.98 Ga ago. Stratigraphic sequence of rilles, wrinkle ridge and domes shows that wrinkle ridges are the oldest, while the rilles are younger than the domes.

9 illus, 2 tables, 49 ref

026268   GORY E, SINHA R K, SAHA D, VINOD T R, CRIPS N R, GAIKWAD P A (Health Information Management Dep, Manipal Academy of Higher Education, Manipal - 576 104, Email: rajesh.sinha@manipal.edu) : Spatio-temporal risk-analysis of cancer endemicity in Sulthan Bathery Taluk of Wayanad District of Kerala- A geo-informatics approach. Indian J Community Med 2018, 43(3), 199-203.

Asian countries have to confront with the global burden of cancer and various environmental factors predisposing the incidence. Geoinformatics can assist in spatial autocorrelation and statistical analysis in determining environmental and demographic correspondence to endemicity. What is of prime importance is the availability of the spatial datasets of cancer cases. The aim of this study was to reveal the distribution pattern of cancer and its magnitude in the eight panchayats of Sulthan Bathery Taluk of Wayanad district. The present study also attempted to develop and implement a data frame facilitating better data collection. This was a taluk-level cross-sectional retrospective analysis and interventional study. A retrospective survey created a geodatabase with 547 cancer cases registered along the timeline of 2015–2016. Input datasets were geocoded using Google Earth Pro software. The analysis was performed using ArcMap-10.2 version. Registration revealed the high breast cancer incidences and temporal increment mainly in town areas. The incidence depicted male predominance and prevalence along the age group of 30–69 years. The pattern showed cancer incidence at a proximity to state borders and forest regions (Noolpuzha) which are high population density regions, instantiated relation of geographic variables, and cancer incidences. The implementation of data frame ensured structured data collection. This study concluded the spatial association of cancer incidence demonstrating the high-risk regions with male predominance and role spatial risk analysis in cancer database management.

7 tables, 17 ref

026267   BANDYOPADHYAY S, RAJ R, PADUA S, RAMACHANDRAN S, JENA R K M, ROY P D, DUTTA D P M, SINGH S K, RAY S K (ICAR-National Bureau of Soil Survey and Land Use Planning, West Bengal- 700 091, Email: siladitya_555@yahoo.co.in) : Priority zoning of available micronutrients in the soils of agroecological sub-regions of North-East India using geo-spatial techniques. Agric Res 2018, 7(2), 200-14.

An attempt was made to identify priority zones of available micronutrients in the soils of agro-ecological subregions (AESR) of north-eastern states of India (Assam, Nagaland, Sikkim and Tripura) using geo-spatial techniques. Surface soil samples (0–25 cm) were collected from Assam (AESRs 15.2, 15.3, 15.4 and 17.1), Nagaland (AESR 17.1), Sikkim (AESR 16.2) and Tripura (AESR 17.2) and analysed for pH, organic carbon and DTPA-extractable micronutrients (Fe, Mn, Zn and Cu) by standard procedures. Regular Spline was employed as spatial interpolation techniques for obtaining spatial distribution of available micronutrients in soils. The AESR map was overlaid on spatial distribution layers to obtain spatial variability of micronutrients in the AESRs of north-eastern regions of India. Zinc deficiency was common in all the AESR. Maximum deficient area of Zn, Mn and Cu was observed in AESR 15.4, and it was regarded as the high-priority zone, whereas AESR 16.2 and AESR 17.2 were considered as low-priority zone. Rainfall, pH and organic carbon appeared to be the key factors in controlling micronutrient availability in soils of north-eastern regions of India.

10 illus, 9 tables, 49 ref

026266   KUMAR A, KUMAR A, NARAYANAN P, HOODA R S (Haryana Space Applications Centre, Panchkula, Email: anup0106@yahoo.com) : Geospatial approach for groundwater resource study in Panchkula district, Haryana. J Env Bio-Sci 2018, 32(1), 87-92.

Of various groundwater exploration techniques, remote sensing satellite data, geographical information system (GIS) and global positioning system (GPS) are highly suitable for searching new groundwater potential sites, planning, development and management of groundwater on need basis in different types of terrain. The Panchkula district, the study area, is situated in the northern part of Haryana State between the geo-coordinates 30⁰26' N to 30⁰ 55' N latitudes and 76⁰46' E to 77⁰10' E longitudes. The total geographical area of the district is 898 sq. km. In the present study, groundwater resource of the district has been studied with the help of IRSP6 LISS-III (2006) satellite data, GIS and ground surveys. Various thematic maps like geology, structure, geomorphology, drainage have been prepared and integrated for groundwater prospects mapping. Field visists have been done to check the interpreted features. The post-field corrections have been done in pre-field maps and finalized all the maps. The study shows that in the district four major groundwater prospects units i.e. older alluvial plain, piedmont/fan surface, flood plain and structural hills are present. The availability of groundwater is good to very good in older alluvial plain which covers 303.53 sq.km (33.80 %) area; moderate to good in piedmont/fan surface which covers 8.6 sq.km (0.96 %) area; very good to excellent in flood plain which covers 43.51 sq.km (4.85 %) area and poor in structural hills which covers 542.36 sq.km (60.39 %) area. The groundwater development i.e. exploitation options are high in older alluvial plain and flood plain, moderate in piedmont/fan surface and low in structural hills. In the district, 347.04 sq.km area is suitable for high groundwater development, 8.60 sq.km area for moderate and 542.36 sq. km area for low groundwater development. In the district, village ponds and small check dams/earthen dams at suitable sites are highly suitable options for groundwater management. In the district, by de-silting of 36 village ponds, 324895.99 m³ volume of water can be harvested. The findings of the study are highly useful for the district in terms of planning, development and management of groundwater to fulfill the increasing demand of water.

9 illus, 2 tables, 11 ref

025042   GOBI K, KANNAPIRAN B, DEVARAJ D, VALARMATHI K (DRDO-Defence Research Development Laboratory, Hyderabad, Email: thilagavathygobi558@gmail.com) : Design, development and performance evaluation of eddy current displacement sensor based pressure sensor with target temperature compensation. Def Sci J 2018, 68(2), 203-9.

In Aerospace applications, pressure measurement plays a vital role as it serves as one of the input to onboard controller to aid decision- making on initiating or terminating some of the critical events. In this paper, the design aspects of pressure sensor using linear eddy current displacement sensor (ECDS) are presented along with its performance evaluation. The static calibration is carried out to select the best position of ECDS in the proposed pressure sensor. The effect of target temperature on sensor output is presented with test results to aid compensation. A compensation algorithm is developed to minimise the error due to target temperature. The developed compensation algorithm is validated using thermal calibration. The designed pressure sensor is calibrated using Arson dynamic pressure calibrator to evaluate its bandwidth. The calibration results are analysed to aid future sensor design towards improvement of accuracy, bandwidth and miniaturisation.

10 illus, 5 tables,16 ref

025041   JOHNY C J, PRASAD V S (Ministry of Earth Sciences, Noida- 201 309, Email: vsprasad@ncmrwf.gov.in) : Quality and impact of GPSRO observations from Megha-Tropique satellite on NGFS model. Curr Sci 2018, 114(5), 1083-8.

Megha-Tropique satellite mission launched in 2011 was aimed at providing more observations in the tropical region. In the initial phase of the mission, it was found that the quality of global positioning system radio occultation (GPSRO) observations was not satisfactory. The Indian Space Research Organisation (ISRO) took remedial measures in this regard by modifying the data processing algorithm and releasing the new version of data. In 2012, an observing system simulation experiment (OSSE) was done at National Centre for Medium Range Weather Forecasting (NCMRWF) using simulated data at MeghaTropiques ROSA observation location with Global Forecast System (GFS) based model. As an extension of the previous study, the quality of new version of GPSRO bending angle observations and impact of assimilation of these observations in NCMRWF GFS (NGFS) model were studied. It was found that with the use of a new data processing algorithm, quality of bending angle observations improved and comparable with other GPSRO missions in the pressure range between 500 hpa and 200 hpa. Impact study shows that the new observations improved forecasts in the middle and upper levels in the tropics.

7 illus, 1 table, 22 ref

023338   GNANANANDA K, REDDY B S (VTU Extension Centre, Bangalore, Email: Subbreddy.bandi@honeywell.com) : Conflict free flight path: A design study for automation. J Aerospace Sci Technol 2018, 70(1), 64-9.

A number of future air traffic management concepts are being studied to enhance efficiency and flight safety. Conflict Detection and Resolution (CDR) is one such initiative for operation much beyond the capability of the conventional Traffic Collision Avoidance System where the resolutions are generally in terms of changing speed or heading depending upon the situation. The design studies presented in this paper investigate possibility of generating heading change commands and integrating with Autopilot for closed loop operation for conflict resolution as well as for recovering the flight path to the original flight leg. Simulation results for open loop and closed loop operation are presented to validate the approach. Topics requiring further studies are highlighted.

9 illus, 14 ref

023337   SITARAM N (School of Aeronautical Sciences, Hindustan Institute of Technology and Science, Chennai, Email: nsitaram.iitm@gmail.com) : Semi nulling calibration of a five hole probe. J Aerospace Sci Technol 2018, 70(1), 47-57.

Five hole probes are extensively used for measuring three dimensional flows. However the useful range of the probe is limited to about 30°. In many flows, this range may be exceeded. In such flows, a seven hole or even a nine hole probe is required increasing testing time or using alternative methods. The objective of the present paper is to find one such alternative method for use of five hole probes in highly three dimensional flows. A large size probe is manufactured and calibrated in an open jet calibration tunnel at a velocity of 40 m/s in yaw angle range of +90° and pitch angle range of -70° to 90° at an interval of 10°. The probe calibration data is used for nulling calibration with zero yaw angle and pitch angle range of about # 70°. This method is time consuming. Hence a semi nulling calibration method is developed. This method is similar to non-nulling calibration method. However the range of yaw angle is limited to + 20°. If the flow yaw angle exceeds this yaw angle range, the probe can be rotated, so that the probe can be used to measure flows with large yaw and pitch angles. The calibration curves of semi nulling method are compared with those of zonal non nulling calibration method. It is found that the pitch angle range of non nulling calibration method is one pitch angle interval less than that of semi nulling method.

8 illus, 3 tables, 14 ref

023336   SURYANARAYANA G K, NAVEEN K M, MUDKAVI V Y (CSIR-National Areospace Laboratries, Bangalore, Email: gksuryanal@gmail.com) : Mimicking the mechanism of lift generation in dragonflies. J Aerospace Sci Technol 2018, 70(1), 42-6.

Human pursuit of flight has learnt many lessons from nature and a few adaptations have led to phenomenal progress. Insect flight uses complex unsteady aerodynamics to generate lift in addition to producing thrust. A close look at the dragonfly provides some clues to mimic its flight using passive means by separating propulsion and lifting mechanisms. Though the dragonfly can independently flap each of its wings to generate lift and thrust, during forward flight, fore-wings alone flap while the aft-wings remain nearly steady. We adopt this as basis for new passive configurations to generate steady lift. Conceptually, we replace fore-wings with a cylinder that is known to shed vortices, to mimic flapping. A simple plate replaces the aft-wings. Flow analysis of such a configuration at Reynolds Number of 7500 revealed a steady flow topology featuring a trapped vortex over the plate, resulting in steady lift to drag ratio of 3. A further optimized configuration consisting of a semi-circular cylinder upstream and a cambered plate downstream resulted in lift to drag ratio of 14.5, which is considerable for these flow regimes, opening up new possibilities for design of nano-flight vehicles.

11 illus,19 ref

023335   CHIKMATH L, DATTAGURU B (Aerospace Engineering Dep, International institute for Aerospace Engineering and Management, Bangalore, Email: lokamanyachikmath@gmail.com) : Study on non-linear contact stresss and prognosis analysis of lug joints with misfits. J Aerospace Sci Technol 2018, 70(1), 27-41.

Components of aircraft and other large scale structures are generally made in parts in order to facilitate easy manufacturing, assembly and dis-assembly. Lug joints with fasteners are preferred in several aerospace applications where their purpose is to connect primary load carrying members. Study on structural integrity of these types of joints becomes mandatory from the safety point of view. This requires in-depth understanding of science and technology of Structural Health Monitoring (SHM) at these joints. Analysis presented here deals with the critical locations of interference and clearance fit lug joints which continuously operate under fatigue loading. Both interference and clearance fits exhibit non-linear contact-stress variation above certain load level and this effect needs to be addressed for both fatigue and monotonic loading. The maximum Pull or Push loads causes high stress concentrations at critical locations along the pin-hole interface. With continuous usage of the component, crack like damages initiate at these locations and they grow till failure of the component. The non-linear prognosis analysis is carried out to generate the data required for SHM at any stage which can be used to estimate remaining life of the component.

15 illus, 3 tables, 24 ref

023334   RENJI K, PRABHAKAR V, DIVYA K (Advanced Technology Development Group, ISRO Satellite Centre, Bangalore, Email: renji@isac.gov.in ) : Force distribution at indeterminate structural interfaces of large elements of spacecraft. J Aerospace Sci Technol 2018, 70(1), 17- 26.

Spacecraft is an assemblage of several elements and many of these elements have statically indeterminate interfaces. The distribution of forces at their interfaces depends on the stiffness at these interfaces. It is expected that the forces at the interface of a subsystem are significant in regions that are relatively stiff. It is shown here that this behavior is true when the force acts only on the specific subsystem and no forces act on the rest of the elements. If the forces act on the entire system the force distribution at the interface of a subsystem is significantly modified by the deformation at these interfaces which are caused due to the forces acting on the rest of the elements. The forces can be significant even at locations where the stiffness is low. These characteristics are concluded using a spring-mass model. Using the results of finite element model these findings are then demonstrated for the forces at the interfaces of a propellant tank mounted in a spacecraft. Similar characteristics of force distribution are seen in the natural modes of vibration. Experimental results are obtained and they show good agreement with the above findings. 

12 illus, 2 tables, 7 ref

023333   KALIRAJAN K, JOSHI A (Aerospace Engineering Dep, Indian Institute of Technology, Bombay, Email: karthik.aero.iitb@gmail.com) : Ballistic missile trajectory design considering impact angle constraint. J Aerospace Sci Technol 2018, 70(1), 1-16.

The current paper investigates the problem of guiding ballistic re-entry vehicles to the terminal point under the additional terminal constraint of final flight path angle. In this regard, the classical Lambert's Problem is reformulated to include the final flight path angle constraint. The proposed solution of the modified Lambert's problem consists of a minimum of two different trajectories starting from the same initial location and intersecting each other at a location, which is determined by applying the desired time of flight and terminal flight path angle constraints. The modified Lambert strategy is shown to satisfy terminal flight path angle constraint along with the time of flight, initial and final location constraints. This scheme requires the ballistic vehicle to perform an additional stage burn during descent in-order to switch from an initial trajectory, using Lambert strategy, to a final trajectory which satisfies the final flight path angle constraint. An additional stage burn is provided such that the position and velocity of the vehicle traveling in the initial trajectory is matched with that required for it to be on the final trajectory. It is also found that the amount of propellant required for the trajectory transfer, is dependent on the total time of flight and the altitude at which the additional stage burn occurs. The optimal values of these two parameters are found using interior-point optimization technique.

17 illus,1 table,10 ref

023332   RAJU M A, RANGANAYAKULU C (Aeronautical Development Agency, Bangalore, Email: amaranatha@yahoo.com) : Heat transfer and friction correlations for R134a with offset strip fin surface. J Aerospace Sci Technol 2017, 69(4), 615-27.

Single phase heat transfer analysis of R134a refrigerant (liquid phase) has been carried out using Computational Fluid Dynamics (CFD) approach for offset strip fin. Colburn j factor and Fanning friction factor are predicted for offset strip fin. The correlations are developed at Reynolds number range of 100-15000. The effect of fin geometry (fin spacing, fin height, fin thickness and lance length) on the enhanced heat transfer and pressure drops were investigated. Colburn j factor and fanning friction factor f, correlations have proposed in terms Re and geometry parameters (h/s, t/s, t/l) for liquid refrigerant R134a in the present study. Two separate correlations have proposed for the low and high Re regions i.e. Between Re of 100-1000 and Re of 1000-15000. The numerical results are validated with experimental results, results are found in good agreement with experimental results. Variation is found less than 5%. 

9 illus, 2 tables,19 ref

023331   MEHTA R C (Aeronautical Engineering Dep., Noorul Islam Univ, Kumaracoil, Email: drrakhab.mehta@gmail.com ) : Isoparametric finite element method to generate structured grid for numerical flow simulation. J Aerospace Sci Technol 2017, 69(4), 588-96.

Eight-nodded quadrilateral finite element is used to generate structured grid for a numerical simulation. The computational domain is sub-divided into number of quadrilateral regions that display the geometry of each sub-domain. The inner and the outer boundaries of the computational domain are described in terms of the surface coordinates. An algebraic homotopy procedure is used to generate grid clustering in order to resolve boundary layer. The structured grid is linked with the flow solver based on finite volume of space discretiztion scheme with multi-stage Runge-Kutta time stepping technique. Examples are illustrated to demonstrate the grid generation procedure and data processing for a forward facing aero-disc spike attached to a hemispherical blunt body at Mach 6 and over a heat shield of a satellite launch vehicle at Mach 0.8 at an angle of attack 5 deg. The present grid generation method is convenient for checking the grid independence test by varying the stretching factor. The quadrilateral grid generated by finite element, vector plot of velocity and contour plots of the computed flow field data are easily drawn with the help of MATLAB.  

9 illus, 32 ref

023330   LAXMINARAYANA A, VIJAYAKUMAR R (Rotary Wing R & D Dep, Hindustan Aeronautics Limited, Bangalore, Email: alnarayana2005@gmail.com) : Strength prediction and damage assessment of laminated composite plates with rectangular/square cutout using finite element method. J Aerospace Sci Technol 2017, 69(4), 574-87.

The progressive failure analysis of symmetrically laminated rectangular composite plate [0/+457-45/90]2s with square/rectangular cutout under uniform uniaxial compression loading is carried out using finite element method. Hashins failure criterion is used to predict the failure of lamina. A parametric study has been carried out to study the influence of square/rectangular cutout size, cutout orientation and plate thickness on the ultimate failure load of laminated composite plate under uni-axial compression loading. Ultimate failure loads were computed for six different laminate configurations (0/+45/-45/90]2s, [75/-60/30/-15]2s, [0/90]4s, [-45/45]4s, [157-75]4s, [30/-60]4s. It is observed that the laminate stacking sequence, plate thickness , cutout size and cutout orientation has substantial influence on the ultimate failure load of notched composite plates.

10 illus, 2 tables, 23 ref

023329   MURUGAN J N (CSIR-National Aerospace Laboratories, Bangalore, Email: jpnarayan80@gmail.com ) : Supersonic flow seperation in front of a forward-facing step. J Aerospace Sci Technol 2017, 69(4), 563-73.

A detailed experimental study has been done to understand the Shock Wave-Boundary Layer Interaction (SWBLI) over a Forward-Facing Step (FFS) of height (h) in a Mach 2.5 flow using Particle Image Velocimetry (PIV). In addition to PIV, unsteady wall pressure measurements, high-speed schlieren and surface oil flow visualization have been studied. Flow separation using surface oil flow visualization was observed around 4.1 step heights upstream of the step face. Shock motions extracted from the schlieren image sequence shows a peak frequency of approximately 1000 Hz, which corresponds to the dominant (low) frequency at which the shock oscillates; this being two orders in magnitude smaller than the characteristics frequency of the incoming boundary layer. Also, spectra of the unsteady wall pressure data shows that the shock oscillates with a peak frequency of approximately 1000 Hz. The effect of shock location (xs) from instantaneous velocity PIV fields in the cross-stream plane due to an upstream influence parameter (line-averaged boundary layer streamwise velocity, ul) and a downstream parameter (separation bubble or recirculation region area, A) is studied. Instantaneous cross-stream PIV measurements show significant variations of the separation shock location, incoming boundary layer velocity fluctuations and recirculation region. Besides, conditionally averaged velocity field based on incoming boundary layer streamwise velocity fluctuations and separation bubble area in the cross-stream plane shows that the shock location (xs) is correlated to the size of the separation bubble and not to boundary layer velocity fluctuations.

12 illus,16 ref

023328   GUPTA Y, AJITHKUMAR B, KALE H S, NAYAK S, SABHAPATHYB S, SURESHKUMAR S, SWAMI R V (National Centre for Radio Astrophysics-TIFR, Pune- 411 007, Email: ygupta@ncra.tifr.res.in) : The upgraded GMRT : Opening new windows on the radio universe. Curr Sci 2017, 113(4), 707-14.

The Giant Metrewave Radio Telescope (GMRT) is today a frontline international facility for low- frequency radio astronomy, that has produced several exciting and important new results in the 15 years that it has been operational. To keep the GMRT competitive in the global arena in the future, a major upgrade of the observatory is nearing completion that will increase its sensitivity by up to three times and make it a more powerful and versatile facility. We describe the main goals of this upgrade, highlight the technical features and challenges, outline the science potential and update the current status of this venture.

5 illus, 1 table, 61 ref

023327   DATAR V M, MONDAL N K (INO Cell, Tata Institute of Fundamental Research, Mumbai- 400 005, Email: vivek.datar@gmail.com) : India-based neutrino observatory. Curr Sci 2017, 113(4), 701-6.

India has a rich history in neutrino physics. The first ever atmospheric neutrino interaction was observed in the deep underground laboratory at the Kolar Gold Fields (KGF) Karnataka in 1965. This laboratory later also looked for nucleon decay and placed limits. The KGF underground laboratory ceased its operation in 1992 due to the closure of the mine. The India-based Neutrino Observatory (INO) project is a recent initiative to develop a new underground laboratory to conduct experiments in the area of neutrino physics and dark matter searches under a mountain with at least 1000 m rock cover. It is expected that over the years, INO will become a full-fledged underground science laboratory hosting experiments that can exploit its special low background environment and infrastructure.

5 illus, 5 ref

023326   HASN S S, BANERJEE D, RAVINDRA B, RANGARAJAN K E (Indian Institute of Astrophysics, Bengaluru-560 034, Email: hasan@iiap.res.in) : National large solar telescope. Curr Sci 2017, 113(4), 696-700.

The National Large Solar Telescope (NLST) aims primarily to carry out observations of the solar atmosphere with high spatial, spectral and temporal resolution. A comprehensive site characterization programme, that commenced in 2007, has identified an excellent site in the Ladakh region at the Pangong lake, India. With an innovative optical design, NLST is an on-axis Gregorian telescope with a low number of optical elements to reduce the number of reflections and yield a high throughput with low polarization. In addition, it uses high-order adaptive optics to produce close to diffraction limited performance. To control atmospheric and thermal perturbations of the observations, the telescope will function with a fully open dome, to achieve its full potential atop a 25 m tower. The post-focus instruments include broadband and tuneable Fabry–Perot narrow band imaging instruments and a high-resolution spectropolarimeter.

2 illus, 8 ref

023325   KOUL R (Astrophysical Sciences Division, Bhabha Atomic Research Centre, Mumbai- 400 085, Email: rkoul@barc.gov.in) : MACE gamma-ray telescope – a status update. Curr Sci 2017, 113(4), 691-5.

A 21 m diameter imaging atmospheric Cherenkov telescope is being installed at the high-altitude astronomical site at Hanle in the Ladakh region of North India. When operational by 2018, it will have the distinction of being the largest gamma-ray telescope in the northern hemisphere and the second largest in the world. Operating at a trigger threshold energy of <20 GeV, it will play an important role in understanding very high energy processes in the Universe.

5 illus, 13 ref

023324   VENKATAKRISHNAN P, MATHEW S K, SRIVASTAVA N, BAYANNA A R (Physical Research Laboratory, Udaipur-313 001, Email: venkatakrishnan@iiap.res.in) : The multi application solar telescope. Curr Sci 2017, 113(4), 686-90.

Multi Application Solar Telescope (MAST), a telescope for the detailed study of solar activity, was operationalized at the Udaipur Solar Observatory (USO) of Physical Research Laboratory (PRL), on 16 June 2015. This article traces the history of the conceptualization to realization of MAST and describes its salient features. MAST is an off-axis Gregorian-Coudéent features. MAST is an off-axis Gregorian-Coudé magnetic fields and a multi-slit spectro-polarimeter. An adaptive optics system is also being developed for the on-line corrections of the image distortions produced by atmospheric seeing. The main objective of MAST is to obtain high spatial and temporal resolution observations of solar photospheric and chromospheric activity, with the ultimate goal of predicting.

6 illus, 6 ref

023323   OMAR A, KUMAR B, GOPINATHAN M, SAGAR R (Aryabhatta Research Institute of Observational Sciences, Nainital-263 002, Email: aomar@arises.res.in) : Scientific capabilities and advantages of the 3.6 meter optical telescope at Devasthal, Uttarakhand. Curr Sci 2017, 113(4), 682-5.

India’s largest 3.6 m aperture optical telescope has been successfully installed in the central Himalayan region at Devasthal, Nainital district, Uttarakhand.The primary mirror of the telescope uses the active optics technology. The back-end instruments, enabling spectroscopic and photometric imaging of the celestial sky are designed and developed by ARIES along with other Indian institutes. The Devasthal optical telescope in synergy with two other highly sensitive telescopes in the country, namely GMRT operating in the radio wavebands and AstroSat operating in the high-energy X-ray, ultraviolet and visual wavebands, will enable Indian astronomers to carry out scientific studies in several challenging areas of astronomy and astrophysics.

2 illus, 9 ref

023322   BHALERAO V (Physics Dep., Indian Institute of Technology, Mumbai- 400 076, Email: varunb@iitb.ac.in) : Multi-messenger astronomy. Curr Sci 2017, 113(4), 678-81.

Modern astrophysics utilizes data from a wide variety of channels extending beyond the conventional optical, radio and X-ray observations. Technological developments have augmented electromagnetic (EW) observations with data from cosmic ray detectors, neutrino detectors and recently from gravitational wave (GW) observatories – together forming the core of multi-messenger astronomy. Each ‘messenger’ carries complementary information about various physical processes occurring in an astrophysical source. Combining data from all these channels makes it possible to piece together a more detailed understanding of sources than any single channel can. In this article I discuss multi-messenger astronomy with emphasis on joint EM and GW studies.

35 ref

023321   SOURADEEP T, RAJA S, KHAN Z, UNNIKRISHNAN C S, IYER B (Inter-Univ Centre for Astronomy and Astrophysics, Pune- 411 007, Email: tarun@iucaa.in) : LIGO-India – a unique adventure in Indian science. Curr Sci 2017, 113(4), 672-7.

LIGO-India is an ambitious, large scale mega-science project that will establish a state-of-the-art advanced LIGO gravitational wave (GW) observatory on Indian soil in collaboration with the LIGO Laboratory in the USA. LIGO-India is expected to commence science in 2024 as a key element of a global array of gravitational wave observatories. Beyond the first direct detection of gravitational waves announced in February 2016 by LIGO Science Collaboration, LIGO-India brings forth a great opportunity for Indian scientists and technologists for leadership at the frontier, a new window of gravitational-wave astronomy to probe the universe.

5 illus, 1 table, 6 ref

023320   DHURANDHAR S, SATHYAPRAKASH B S (Inter-Univ Centre for Astronomy and Astrophysics, Pune- 411 007, Email: sanjeev@iucaa.in) : Cosmic sirens: Discovery of gravitational waves and their impact on astrophysics and fundamental physics. Curr Sci 2017, 113(4), 663-71.

On 14 September 2015, the twin detectors belonging to the Laser Interferometer Gravitational Wave Observatory (LIGO) made a triple discovery: the first direct detection of gravitational waves (GWs), first observation of formation of a black hole and first observation of a binary black hole. Since then LIGO has reported two other events and a marginal candidate. These discoveries have heralded a new era in observational astronomy. They will help us in exploring extremes of astrophysics and gravity. GWs are our best chance of getting an idea of what went on a small fraction of a second after the big bang, even if that takes many more decades. With LIGO’s discoveries we hope to solve many puzzles in astronomy and fundamental physics, but GWs are guaranteed to show up objects and phenomena never imagined before.

1 illus, 1 table, 45 ref

023319   RAAB F J, REITZE D H (LIGO Hanford Observatory, USA- 99352, Email: fred.raab@ligo.org) : The first direct detection of gravitational waves opens a vast new frontier in astronomy. Curr Sci 2017, 113(4), 657-62.

We review the first direct detection of gravitational waves in the first observing run of the newly installed Advanced LIGO gravitational-wave detectors. This opens a new window on the universe, using an entirely new phenomena as the messenger to explore the cosmos. We also describe prospects for the future exploration of this new frontier.

8 illus, 28 ref

023318   DIAMOND P, GUPTA Y (SKA Organisation, Pune- 411 007, Email: p.diamond@skatelescope.org) : India and the square kilometre array. Curr Sci 2017, 113(4), 649-56.

The Square Kilometre Array (SKA), the world’s next- generation radio telescope, is being designed by an international consortium. It will, once complete, deliver capability for a broader range of science than any other facility. Indian scientists and engineers have concept and its science case, in the design of the instrument and, hopefully, will do so in the construction and operation. This article describes the current status of the global project with a focus on India’s role in the global collaboration.

5 illus, 11 ref

023317   SKIDMORE W, ANUPAMA G C, SRIANAND R (Thirty Meter Telescope International Observatory, U.S.A.- 91125, Email: was@tmt.org) : The thirty meter telescope international observatory facilitating transformative astrophysical science. Curr Sci 2017, 113(4), 639-48.

The next major advancement in astronomy and cosmology will be driven by deep observations using very sensitive telescopes with high spatial and spectral resolution capabilities. An international consortium of astronomers, including Indian astronomers are building the Thirty Meter Telescope to achieve break-throughs in different areas of astronomy starting from studies of the solar system to that of the early universe. This article provides a brief overview of the telescope, science objectives and details of the first light instruments.

12 illus, 1 table, 15 ref

023316   REDDY B E, RAMAPRAKASH A N (Indian Institute of Astrophysics, Bengaluru- 560 034, Email: ereddy@iiap.res.in) : India's participation in the thirty meter telescope international observatory project. Curr Sci 2017, 113(4), 631-8.

The Thirty Meter Telescope International Observatory (TIO) is being built by an international consortium of institutes and universities in Canada, China, India, Japan and USA. The estimated cost is about US$ 1.47 billion (2012 base year). At present, it is planned to be built on Mauna Kea, Hawaii, at an altitude of about 4000 m.The mountain is already home to many of the world’s largest telescopes. The Union Cabinet chaired by the Prime Minister, at its meeting held on 24 September 2014, approved India’s participation in the TIO project at a total cost of Rs 1299.80 crores. Only about 30% of India’s contribution to the project will be made in cash to be utilized for building common facilities and infrastructure. The rest will be made through design, development and manufacturing of a number of hardware, software and optical components. India’s participation in the TIO is an extramural national project jointly funded by the Department of Science and Technology (DST) and the Department of Atomic Energy (DAE). To successfully deliver India’s in-kind contributions, the two funding agencies have jointly set up the India TMT Coordination Centre (ITCC) which is located at the Indian Institute of Astrophysics (IIA), Bengaluru. IIA along with the Aryabhatta Research Institute of Observational Sciences, Nainital and the Inter-University Centre for Astronomy and Astrophysics, Pune are the key institutes which manage the India TMT project through ITCC. Being a major extra-mural national effort, several other institutes as well as universities participate in the technological, developmental and scientific aspects of the initiative.

9 illus, 7 ref

023315   STONE E, BOLTE M (Physics, Mathematics and Astronomy Dep, California Institute of Technology, U.S.A.- 91125, Email: bolte@ucolick.org) : Development of the thirty-meter telescope project. Curr Sci 2017, 113(4), 628-30.

The Thirty-Meter Telescope (TMT) project is a well- advanced effort to construct one of the first of the next generation of extremely large telescopes with primary mirror diametre larger than 25 m. When used with an adaptive optics systems capable of producing diffraction-limited images, the science reach of a 30 m telescope is extraordinary with improvements in sensitivity over existing telescopes by as much as a factor of 80 for some kinds of observations. The TMT design extends that of the twin Keck 10 m telescopes now in operation and uses the same close-packed segmented primary mirror. The partnership that will finish the design, construct and operate the telescope is described.

5 ref

023314   SANKARASUBRAMANIAN K, SUDHAKAR M, NANDI A, RAMADEVI M C, ADONI A A (ISRO Satellite Centre, Bengaluru- 560 037, Email: sankark@isac.gov.in) : X-ray spectrometers on-board Aditya-L1 for solar flare studies. Curr Sci 2017, 113(4), 625-7.

Aditya-L1 mission will carry two high-spectral resolution X-ray spectrometers to study solar flares.The soft X-ray spectrometer will cover the energy range from 1 to 30 keV, while the hard X-ray spectrometer will cover from 10 to 150 keV. These two instruments together will provide opportunities to study the plasma parameters during solar flares as well as acceleration mechanisms of energetic particles during the flaring time.

4 illus,10 ref

023313   JANARDHAN P, VADAVALE S, BAPAT B, SUBRAMANIUM S K (Physical Research Laboratory, Ahmedabad- 380 009, Email: jerry@prl.res.in) : Probing the heliosphere using in situ payloads on-board Aditya-L1. Curr Sci 2017, 113(4), 620-4.

Aditya-L1, the first ever Indian scientific space mission dedicated to probe the Sun, our nearest star, is slated for launch by the Indian Space Research Organisation (ISRO) most likely in 2020, the year coinciding with the expected start of the rising phase of solar cycle 25. Of the seven science payloads on-board Aditya-L1, three are in situ instruments, namely the Aditya Solar wind Particle EXperiment, the Plasma Analyser Package for Aditya and a magnetometer package. These three payloads will sample heliospheric data from the L1 Lagrangian point of the Sun–Earth system, at a distance of ~1% of the distance to the Sun, along the Sun–Earth line. This is therefore a unique opportunity for the solar physics community to gain a better understanding of the inner heliosphere and predict space weather more accurately.

37 ref

023312   TRIPATHI D, RAMAPRAKASH A N, KHAN A , GHOSH A, CHATTERJEE S (Inter-Univ Centre for Astronomy and Astrophysics (IUCAA), Pune- 411 007, Email: durgesh@iucaa.in) : The solar ultraviolet imaging telescope on-board Aditya-L1. Curr Sci 2017, 113(4), 616-9.

The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument on-board Aditya-L1 mission of ISRO that will measure and monitor the solar radiation emitted in the near ultraviolet wavelength range (200–400 nm). SUIT will simultaneously map the photosphere and chromosphere of the Sun using 11 filters sensitive to different wavelengths and covering different heights in the solar atmosphere and help us understand the processes involved in the transfer from mass and energy from one layer to the other. SUIT will also allow us to measure and monitor spatially resolved solar spectral irradiance that governs the chemistry of oxygen and ozone in the stratosphere of the Earth’s atmosphere. This is central to our understanding of Sun–climate relationship.

5 illus, 1 table, 4 ref

023311   PRASAD B R, BANERJEE D, SINGH J, NAGABHUSANA S, KUMAR A (Indian Institute of Astrophysics, Bengaluru-560 034, Email: brp@iiap.res.in) : Visible emission line coronagraph on Aditya-L1. Curr Sci 2017, 113(4), 613-5.

Solar coronagraph mimics total solar eclipse by blocking the solar disk and enabling the observation of extended coronal atmosphere of the Sun. Visible Emission Line Coronagraph (VELC), on-board Aditya-L1 space mission, is an internally occulted solar coronagraph capable of simultaneous imaging, spectroscopy and spectro-polarimetry close to the solar limb. This payload is designed to study the coronal plasma and heating of the solar corona. Studying development, dynamics and origin of coronal mass ejections and measurement of coronal magnetic fields over active regions are other important science goals. VELC is designed to image the solar corona at 500 nm with an angular resolution of 5?? over a field of view (FOV) of 1.05–3 spectroscopy Ro. It also facilitates simultaneous at three emission lines, multi-slit viz. Fe XIV (530.3 nm), Fe XI (789.2 nm) and Fe XIII (1074.7 nm) with a spectral resolution of 28 , 31 and 202 mÅ/pixel respectively, has a dual-beam over an spectro-polarimetry FOV of 1.05–1.5 Ro. channel The payload for magnetic field measurements at 1074.7 nm.

1 illus, 6 ref

023310   SEETHA S, MEGALA S (ISRO Headquarters, Bengaluru- 560 231, Email: seetha@isro.gov.in) : Aditya-L1 mission. Curr Sci 2017, 113(4), 610-2.

Aditya-L1 is the first Indian space mission to study the Sun. The mission is aimed at studying the Sun from a halo orbit around the Sun–Earth Lagrangian point 1, which is about 1.5 million kilometres from the Earth. It carries seven payloads to observe the photosphere, chromosphere and the outermost layers of the Sun, the corona, in different wavebands. The spacecraft and payloads are under development. Aditya-L1 is expected to be launched during the 2019–20 time-frame by PSLV-XL.

5 illus, 1 table, 4 ref

023309   SINGH K P, BHATTACHARYA D (Astronomy and Astrophysics Dep, Tata Institute of Fundamental Research, Mumbai-400 005, Email: kulinderpal@gmail.com) : Multi-colour hues of the universe observed with AstroSat. Curr Sci 2017, 113(4), 602-9.

India’s space astronomy observatory AstroSat was launched on 28 September 2015, carrying instruments to observe cosmic sources over a large spectral band, from optical/UV to hard X-rays. The mission, with all its payloads, has been operating successfully since its launch. After an initial period of performance verification and calibration, the satellite is now in full science operation. This article gives a brief introduction about the capabilities of the mission and presents some of the early science results.

10 illus, 1 table, 21 ref

023308   RAMADEVI M C, SEETHA S, BHATTTACHARYA D, RAVISHANKAR B T, MEENA G (ISRO Satellite Centre, Bengaluru- 560 037, Email: ramadevi@isac.gov.in) : Scanning sky monitor on-board AstroSat. Curr Sci 2017, 113(4), 599-601.

Scanning Sky Monitor (SSM) on-board AstroSat is a wide-field imager to monitor the X-ray sky in the energy band 2.5–10 keV. The primary science objective of SSM is to detect and locate transient X-ray sources in the sky. Once detected the information is to be provided to the astronomical community for follow-up observations to do a more detailed study of the source. Long-term monitoring of known X-ray transient sources is also one of the science objectives of SSM. The instrument constitutes three units of 1D position- sensitive propotional counters with coded masks on each, all three mounted on a platform capable of rotation to scan about 50% of the sky in one full rotation. The angular resolution of each unit in SSM is 12? × 2.5°. Sensitivity of SSM is ~30 milliCrab at 3 sigma in 10 min integration time. This article briefly discusses the instrument and a few early results since the launch of AstroSat.

5 illus, 10 ref

023307   RAO A R, BHATTACHARYA D, BHALERAO V B, VDAVALE S V, SREEKUMAR S (Tata Institute of Fundamental Research, Mumbai-400 005, Email: a.raghu.rao@gmail.com) : Cadmium–Zinc–Telluride Imager on-board AstroSat: A multi-faceted hard X-ray instrument. Curr Sci 2017, 113(4), 595-8.

The AstroSat satellite is designed to make multi- waveband observations of astronomical sources and the Cadmium–Zinc–Telluride Imager (CZTI) instrument of AstroSat covers the hard X-ray band. CZTI has a large area position-sensitive hard X-ray detector quipped with a coded aperture mask, thus enabling simultaneous background measurements. Ability to record simultaneous detection of ionizing interactions in multiple detector elements is a special feature of the instrument, and this is exploited to provide polarization information in the 100–380 keV region. CZTI provides sensitive spectroscopic measurements in the 20–100 keV region, and acts as an all-sky hard X-ray monitor and polarimeter above 100 keV. During the first year of operation, CZTI has recorded several gamma-ray bursts, measured the phase-resolved hard X-ray polarization of the Crab pulsar, and the hard X-ray spectra of many bright galactic X-ray binaries. The excellent timing capability of the instrument has been demonstrated with simultaneous observation of the Crab pulsar with radio telescopes like Gaint Metrewave Radio Telescope and Ooty Radio Telescope.

5 illus,10 ref

023306   YADAV J S, AGARWAL P C, ANTIA H M, MANCHANDA R K, PAUL B (Tata Institute of Fundamental Research, Mumbai-400 005, Email: jsyadav@tifr.res.in) : Large area X-ray proportional counter instrument on AstroSat. Curr Sci 2017, 113(4), 591-4.

Large Area X-ray Proportional Counter (LAXPC) is one of the major AstroSat payloads. The instrument will provide high time-resolution X-ray observations in 3–80 keV energy band with moderate energy resolution. A cluster of three co-aligned identical LAXPC detectors is used in AstroSat to provide large collection area of more than 6000 sq. cm. The large detection volume (15 cm depth) filled with xenon gas at ~2 atm pressure, results in detection efficiency greater than 50% above 30 keV. With its broad energy range and fine-time resolution (10 ?s), LAXPC instrument is well suited for timing and spectral studies of a wide variety of known and transient X-ray sources in the sky. We have done extensive calibration of all LAXPC detectors using radioactive sources as well as GEANT4 simulation of LAXPC detectors. We describe in brief some of the results obtained during payload verification phase along with LAXPC capabilities.

3 illus,10 ref

023305   SINGH K P, DEWANGAN G C, CHANDRA S, BHATTACHARYA S, CHITNIS V (Tata Institute of Fundamental Research, Mumbai- 400 005, Email: kulinderpal@gmail.com) : Soft X-Ray focusing telescope aboard Astrosat: Early results. Curr Sci 2017, 113(4), 587-90.

The Soft X-ray focusing Telescope (SXT) is a moderate- resolution X-ray imaging spectrometer supplementing the ultraviolet and hard X-ray payloads for broadband studies of cosmic sources with AstroSat. Well suited for observing bright X-ray sources, SXT observations of nearby active galactic nuclei (AGN), binary with compact companions, active stars,etc. are producing long soft X-ray light curves and high-quality spectra. The strong X-ray variability and multiple spectral components exhibited by SXT observations of nearby Seyfert 1 galaxies show excellent promise to probe accretion disks and central engines in AGN through multi-band variability and spectroscopy.

6 illus, 1 table, 6 ref

023304   TANDON S N, GHOSH S K, HUTCHINGS J, STALIN C S, SUBRAMANIUM A (Indian Institute of Astrophysics, Bengaluru- 560 034, Email: sntandon@iucaa.in) : Ultraviolet imaging telescope on Astosat. Curr Sci 2017, 113(4), 583-6.

The AstroSat satellite is designed for multi-wavelength astronomy for observations covering a spectral range from soft and hard X-rays to the ultraviolet. The Ultraviolet Imaging Telescope (UVIT) is the only non-X-ray telescope on AstroSat and it pro-counting mode with full-field readouts every ~35 ms providing positions of all detected photons, which are corrected for distortions in the detectors. Stacking of these positions from many such frames would give an image of the object. However, the pointing of the satellite has a vides the long lever arm to the multi-wavelength obtypical drift of ~1??/s which can increase to ~4??/s during the simultaneous multi-wavelength studies in coordination with the X-ray telescopes on-board AstroSat, UVIT is used to study a large variety of objects with arc second-level spatial resolution. During the first year of observations, UVIT has obtained images in many filter bands in the wavelength range 130–300 nm over a field of ~28?, which are being used to study a variety of hot stars, nebulae, stellar clusters and galaxies.

6 illus, 1 table, 4 ref

023303   SEETHA S, MEGALA S (ISRO Headquater, Bengaluru-560 231, Email: seetha@isro.gov.in) : Overview of the Astrosat mission. Curr Sci 2017, 113(4), 579-82.

AstroSat is the first dedicated astronomy mission of India aimed at simultaneous multi-wavelength observations of celestial sources in X-ray, ultraviolet and limited optical spectral bands. The satellite was from Satish Dhawan Space Centre, Sriharikota on 28 September 2015 by PSLV-C30 (XL) in its 30^th consecutive successful flight. The satellite was special features of AstroSat placed in an orbit with an altitude of 650 km and 6° orbital inclination. Currently, all the payloads are operational and observations are underway. The mission life is expected to be 5 years.

3 illus