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

021346   Singh R;Mishra M K;Chauhan P (Space Applications Centre, Indian Space Research Organisation, Ahmedabad-380 005, Email: prakash@sac.isro.gov.in) : SWIR albedo mapping of mars using mars orbiter mission data. Curr Sci 2017, 113(1), 112-16.

Global apparent short wave infrared (SWIR) (1.64- 1.66 μm) albedo mapping results from data acquired by Methane Sensor for Mars (MSM) onboard Indian Mars Orbiter Mission from October 2014 to February 2015, are presented. Global analysis of low and high albedo patterns is discussed using MSM apparent SWIR albedo map. The occurrence frequency of MSM apparent SWIR albedo shows a clear bimodal behaviour and is in good agreement with OMEGA NIR albedo distribution. Based on MSM apparent SWIR albedo values, three classes (high, intermediate and low albedo values) are defined, which show a clear elevation dependency. Variation of weekly average apparent albedo during the study period over Syrtis Major, Daedalia Planum and Valles Marineris region, respectively, is presented.

6 illus, 16 ref

021345   Mohammed A T (Astronomy Dep, College of Science, Baghdad Univ, Iraq) : Direct detection of photons from exoplanets of a host star leading to study its element compositions. Int J Sci Nat 2017, 8(3), 469-75.

Computer simulations of direct detection of photons from an exoplanet that hidden in the diffraction side loops of the host star are presented. This involves computing the point spread function and the modulation transfer function of a Dirac delta function that observed by optical telescope. Jacquinot Gaussian apodization aperture is suggested to bring the exoplanet up the diffraction loops of the parent star and becomes ready for spectroscopic observations owing to study its element compositions. This approach is capable of detecting exoplanets with angular separation of 4λ/D at contrast ratio of 10 and it is very easy to be manufactured.

13 illus, 12 ref

017489   Subrahmanya C R;Prasad P;Girish B S; Somashekar R;Manoharan P K;Mittal A K (NO, Raman Research Institute, C.V. Raman Avenue, Sadashivnagar, Bengaluru-560 080, Email: mano@ncra.tifr.res.in) : Receiver system for the ooty wide field array. J Astrophys Astr 2017, 38(1), 1-6.

The legacy Ooty Radio Telescope (ORT) is being reconfigured as a 264-element synthesis telescope, called the Ooty Wide Field Array (OWFA). Its antenna elements are the contiguous 1.92 m sections of the parabolic cylinder. It will operate in a 38-MHz frequency band centred at 326.5 MHz and will be equipped with a digital receiver including a 264-element spectral correlator with a - 47 - spectral resolution of 48 kHz. OWFA is designed to retain the benefits of equatorial mount, continuous 9-hour tracking ability and large collecting area of the legacy telescope and use of modern digital techniques to enhance the instantaneous field-of-view by more than an order of magnitude. OWFA has unique advantages for contemporary investigations related to large scale structure, transient events and space weather watch. In this paper, we describe the RF subsystems, digitizers and fibre optic communication of OWFA and highlight some specific aspects of the system relevant for the observations planned during the initial operation.

^iia5 illus, 1 table, 7 ref

017488   Subrahmanya C R;Manoharan P K;Chengalur J N (NO, Raman Research Institute, C. V. Raman Avenue, Sadashivnagar, Bengaluru-560 080, Email: chengalu@ncra.tifr.res.in) : Ooty wide field array. J Astrophys Astr 2017, 38(1), 1-5.

Authors describe here an ongoing upgrade to the legacy Ooty Radio Telescope (ORT). The ORT is a cylindrical parabolic cylinder 530 m x 30 m in size operating at a frequency of 326.5 (or z<126>3.35 for the HI 21-cm line). The telescope has been constructed on a North-South hill slope whose gradient is equal to the latitude of the hill, making it effectively equatorially mounted. The feed consists of an array of 1056 dipoles. The key feature of this upgrade is the digitization and cross-correlation of the signals of every set of 4-dipoles. This converts the ORT into a 264 element interferometer with a field-of-view of 2°x27.4°cos(δ). This upgraded instrument is called the Ooty Wide Field Array (OWFA). This paper briefly describes the salient features of the upgrade, as well as its main science drivers. There are three main science drivers viz. (1) observations of the large scale distribution of HI in the post-reionization era, (2) studies of the propagation of plasma irregularities through the inner heliosphere and (3) blind surveys for transient sources. More details on the upgrade, as well as on the expected science uses can be found in other papers in this special issue.

^iia2 illus, 1 table, 34 ref

017487   Shukla A;Pandey A K;Pathak A (NO, Jaypee Institute of Information Technology, A-10, Sector 62, Noida-201 307, Email: abhishek.shukla@mail.jiit.ac.in) : Benford's distribution in extrasolar world: Do the exoplanets follow benford's distribution?. J Astrophys Astr 2017, 38(1), 1-7.

In - 46 - many real life situations, it is observed that the first digits (i.e., 1,2, ..., 9) of a numerical data-set, which is expressed using decimal system, do not follow a uniform distribution. In fact, the probability of occurrence of these digits decreases in an almost exponential fashion starting from 30.1 % for 1 to 4.6 % for 9. Specifically, smaller numbers are favoured by nature in accordance with a logarithmic distribution law, which is referred to as Benford's law. The existence and applicability of this empirical law have been extensively studied by physicists, accountants, computer scientists, mathematicians, statisticians, etc., and it has been observed that a large number of data-sets related to diverse problems follow this distribution. However, except two recent works related to astronomy, applicability of Benford's law has not been tested for extrasolar objects. Motivated by this fact, this paper investigates the existence of Benford's distribution in the extrasolar world using Kepler data for exoplanets. The quantitative investigations have revealed the presence of Benford's distribution in various physical properties of these exoplanets. Further, some specific comments have been made on the possible generalizations of the obtained results, its potential applications in analysing the data-set of candidate exoplanets.

3 illus, 31 ref

017486   Sarkar A K;Bharadwaj S;Ali S K S (Centre for Theoretical Studies, India Institute of Technology Kharagpur, Kharagpur-721 302, Email: anjan@cts.iitkgp.ernet.in) : Fisher matrix-based predictions for measuring the z = 3.35 binned 21-cm power spectrum using the ooty wide field array (owfa). J Astrophys Astr 2017, 38(1), 1-10.

Authors use the Fisher matrix formalism to predict the prospects of measuring the redshifted 21-cm power spectrum in different k-bins using observations with the upcoming Ooty Wide Field Array (OWFA) which will operate at 326.5 MHz. This corresponds to neutral hydrogen (HI) at z = 3.35, and a measurement of the 21-cm power spectrum provides a unique method to probe the large-scale structures at this redshift. Our analysis indicates that a 5σ detection of the binned power spectrum is possible in the k range 0.05 ≤ k ≤ 0.3 Mpc^-1 with 1000 hours of observation. We find that the signal- to-noise ratio (SNR) peaks in the k range 0.1-0.2 Mpc^-1 where a 10σ detection is possible with 2000 hours of observations. Our analysis also indicates that it is not very advantageous to observe beyond 1000 h in a single field-of-view as the SNR increases rather slowly beyond this in many of the small k-bins. The entire analysis reported here assumes that the foregrounds have been completely removed.

^iia5 illus, 73 ref

017485   Paul K T;Shruthi S B;Subramaniam A (Physics Dep, Christ Univ, Bangalore-560 029, Email: paul.kt@christuniversity.in) : Short-term Hα line variations in classical be stars : 59 cyg and OT gem. J Astrophys Astr 2017, 38(1), 1-10.

Authors present the optical spectroscopic study of two classical Be stars, 59 Cyg and OT Gem obtained over a period of few months in 2009. We detected a rare triple-peak Hα emission phase in 59 Cyg and a rapid decrease in the emission strength of Hα in OT Gem, which are used to understand their circumstellar disks. We find that 59 Cyg is likely to be rapid rotator, rotating at a fractional critical rotation of <126>0.80. The radius of the Hα emission region for 59 Cyg is estimated to be R_d/R * <126> 10.0, assuming a Keplerian disk, suggesting that it has a large disk. We classify stars which have shown triple-peaks into two groups and find that the triple-peak emission in 59 Cyg is similar to ζ Tau. OT Gem is found to have a fractional critical rotation of <126>0.30, suggesting that it is either a slow rotator or viewed in low inclination. In OT Gem, we observed a large reduction in the radius of the Hα emission region from <126>6.9 to <126>1.7 in a period of three months, along with the reduction in the emission strength. Our observations suggest that the disk is lost from outside to inside during this disk loss phase in OT Gem.

3 illus, 8 tables, 41 ref

017484   Pandey K K;Hiremath K M;Yellaiah G (Astronomy Dep, Osmania Univ, Hyderabad-500 007, Email: pandeyou@yahoo.co.in) : Lowering of asymmetry. J Astrophys Astr 2017, 38(1), 1-9.

Asymmetry, a well established fact, can be extracted from various solar atmospheric activity indices. Although asymmetry is being localized within short time scale, it also persists at different time scales. In the present study we examine the character and nature of asymmetry at various time scales by optimizing the data set, in units of Carrington Rotations (CRs), for Sunspot Area (SA) and soft X-ray flare index (FI_SXR). We find from three solar cycles (21-23) that at a small time scale (viz., daily, CRs and monthly) activity appears to be asymmetric with less significance. At larger time scales (≥01 CRs) strength of asymmetry enhances. Number of significant asymmetry points probably depends upon the solar heights. For different combination of data, asymmetry strength appears to be lowered at certain periods <126>06, <126>12, <126>18 CRs (164, 327 and 492 days i.e., harmonics of <126>1.3 years. Owing to similar behavior of emergence of magnetic flux, it is conjectured that - 45 - emergence of flux on the surface probably contributes to the asymmetry of the solar activity.

5 illus, 3 tables, 33 ref

017483   Marthi V R (National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Post Bag 3, Ganeshkhind, Pune-411 007, Email: vrmarthi@ncra.tifr.res.in) : Prowess - a software model for the ooty wide field array. J Astrophys Astr 2017, 38(1), 1-12.

One of the scientific objectives of the Ooty Wide Field Array (OWFA) is to observe the redshifted Hi emission from z <126> 3.35. Although predictions spell out optimistic outcomes in reasonable integration times, these studies were based purely on analytical assumptions, without accounting for limiting systematics. A software model for OWFA has been developed with a view to understanding the instrument-induced systematics, by describing a complete software model for the instrument. This model has been implemented through a suite of programs, together called Prowess, which has been conceived with the dual role of an emulator as well as observatory data analysis software. The programming philosophy followed in building Prowess enables a general user to define an own set of functions and add new functionality. This paper describes a co-ordinate system suitable for OWFA in which the baselines are defined. The foregrounds are simulated from their angular power spectra. The visibilities are then computed from the foregrounds. These visibilities are then used for further processing, such as calibration and power spectrum estimation. The package allows for rich visualization features in multiple output formats in an interactive fashion, giving the user an intuitive feel for the data. Prowess has been extensively used for numerical predictions of the foregrounds for the OWFA Hi experiment.

^iia11 illus, 30 ref

017482   Manoharan P K;Subrahmanya C R;Chengalur J N (NO, Radio Astronomy Centre, NCRA-TIFR, P.O. Box 8, Ooty-643 001, Email: mano@ncra.tifr.res.in) : Space weather and solar wind studies with OWFA. J Astrophys Astr 2017, 38(1), 1-8.

In this paper, we review the results of interplanetary scintillation (IPS) observations made with the legacy system of the Ooty Radio Telescope (ORT) and compare them with the possibilities opened by the upgraded ORT, the Ooty Wide Field Array (OWFA). The stability and the sensitivity of the legacy system of ORT allowed the regular monitoring of IPS on a grid of large number of radio sources and the results of these studies have been useful to understand the physical processes in the heliosphere and space weather events, such as coronal mass ejections, interaction regions and their propagation effects. In the case of OWFA, its wide bandwidth of 38 MHz, the large - 44 - field-of-view of <126>27° and increased sensitivity provide a unique capability for the heliospheric science at 326.5 MHz. IPS observations with the OWFA would allow one to monitor more than 5000 sources per day. This, in turn, will lead to much improved studies of space weather events and solar wind plasma, overcoming the limitations faced with the legacy system. We also highlight some of the specific aspects of the OWFA, potentially relevant for the studies of coronal plasma and its turbulence characteristics.

^iia2 illus, 32 ref

017481   Maghrabi A;Alanazi M;Aldosari A;Almuteri M (National Centre for Applied Physics, King Abdulaziz City for Science and Technology, Riyadh 11442, Saudi Arabia, Email: amaghrabi@kacst.edu.sa ) : Preliminary results of high-energy cosmic ray muons as observed by a small multiwire detector operated at high cutoff rigidity. J Astrophys Astr 2017, 38(1), 1-11.

Solar disturbances modulate primary cosmic rays on different time scales. Studying cosmic ray variation is an important subject that attracts scientists from different disciplines. We have constructed and installed (in Riyadh, Saudi Arabia, Rc =14.4 GV) a three-layer small (20 x 20 cm²) MultiWire Chamber (MWC) telescope to study cosmic ray variations and investigate their influence on various atmospheric and environmental processes. Preliminary results obtained from the developed detector are given. The influence of both atmospheric pressure and temperature was studied. Both the temperature and pressure coefficients were calculated and were consistent with those previously obtained. Short-term cosmic ray periodicities, such as the 27-day period, and its two harmonics, have been identified. Sporadic variations caused by some solar activity processes have been inspected. The obtained results from this detector have been compared to the existing 1 m² scintillator detector, as well as to some of the neutron monitors, showing comparable results.

7 illus, 34 ref

017480   Lahkar N;Kalita S;Duorah H L;Duorah K (Physics Dep, Gauhati Univ, Guwahati-781 014, Email: nanditalahkar1@gmail.com) : Abundances of La<. J Astrophys Astr 2017, 38(1), 1-9.

Yields of nature's rarest isotopes La¹³⁸ and Ta¹⁸⁰ are calculated by neutrino processes in the Ne-shell of density ≈ 10⁴ g/cc in a type II supernova (SN II) progenitor of mass 20 M Mcircumpunet. Two extended sets of neutrino temperature - T_ve = 3, 4, 5, 6 MeV and T_v(μ/τ)= 4, 6, 8, 10, 12 MeV respectively for charged and neutral current processes are taken. Solar mass fractions of the seeds La¹³⁹, Ta¹⁸¹, Ba¹³⁸ and Hf¹⁸⁰ are taken for calculation. They are assumed to be produced in some s-processing events of earlier generation massive 'seed stars' with average interior density - 43 - range ρ≈10³-10⁶ g/cc. The abundances of these two elements are calculated relative to O¹⁶ and are found to be sensitive to the neutrino temperature. For neutral current processes with the neutron emission branching ratio, b_n = 3.81 x 10^-4 and b_n = 9.61 x 10^-1, the relative abundances of La¹³⁸ lie in the ranges 4.48 x 10^-14-2.94 x 10^-13 and 1.13 x 10^-10-7.43 x 10^-10 respectively. Similarly, the relative abundances of Ta¹⁸⁰ lie in the ranges 1.80 x 10^-15-1.17 x 10^-14 and 4.53 x 10^-12-2.96 x 10^-11 respectively for the lower and higher values of the neutron emission branching ratio. For charged current processes, the relative abundances of La¹³⁸ and Ta¹⁸⁰ are found to be in the ranges 1.38 x 10^-9-7.62 x 10^-9 and 2.09 x 10^-11-1.10 x 10^-10 respectively. Parametrized by density of the 'seed stars', the yields are found to be consistent with recent supernova simulation results throughout the range of neutrino temperatures. La¹³⁸ and Ta¹⁸⁰ are found to be efficiently produced in charged current interaction.

4 illus, 2 tables, 20 ref