Paul B C;Paul D
015712 Paul B C;Paul D (Physics Dep, North Bangal University, Siliguri, Dist. Darjeeling-734 013, Email: firstname.lastname@example.org) : Anisotropic bianchi-I universe with phantom field and cosmological constant. Pramana J Phys 2008, 71(6), 1247-57.
Studies an anisotropic Bianchi-I universe in the presence of a phantom field and a cosmological constant. Cosmological solutions are obtained when the kinetic energy of the phantom field is of the order of anisotropy and dominates over the potential energy of the field. The anisotropy of the universe decreases and the universe transits to an isotropic fiat FRW universe accommodating the present acceleration. A class of new cosmological solutions is obtained for an anisotropic universe in case an initial anisotropy exists which is bigger than the value determined by the parameter of the kinetic part of the field. Later, an autonomous system of equations for an axially symmetric Bianchi-I universe with phantom field in an exponential potential is studied. We discuss the stability of the cosmological solutions.
1 illus, 29 ref
Patnaik S;Kamila S K;Roy G S
015711 Patnaik S;Kamila S K;Roy G S (NO, , Plot No. -6 Budheswari Colony, Bhubaneswar-751 006) : Visual binary stars - calculation of orbital parameters of WDS 04374-0951 & WDS 18384+0850. Ultra Scient phys Sci 2009, 21(2), 365-74.
A Study of Binary Stars - its Detection, Resolution & Classification has been undertaken using general diffraction integral. The calculation for the orbits of visual binary stars: WDS04374-0951 & WDS 18384+0850 have been undertaken along with the determination of the mass, dynamical parallax and ephemerid by using data available in ADS.
5 illus, 3 tables, 23 ref
Kumaravel S;Gurugnanam P;Suresh M; Senthilkumar m;Sivanatarajan G
015710 Kumaravel S;Gurugnanam P;Suresh M; Senthilkumar m;Sivanatarajan G (Earth Sciences Dep, Annamalai University, Annamalai Nagar, Chidambaram, Tamil Nadu, Email: email@example.com) : Demarcate groundwater favorable zones through geophysical and GIS study in Parivillikottai Firka, Tuticorin district, Tamilnadu, India. Ultra Scient phys Sci 2009, 21(2), 375-86.
GIS is a powerful tools in analysing the multiple thematic maps at a lime. GIS analysis is carried out in the present study to locate favorable shallow and deep groundwater bearing zones. To do this subsurface investigation and its interpretation were carried out through geophysical survey. Fifteen vertical electrical soundings (YES) survey were carried out in the study area. The field data were interpreted by RESIST software to determine the resistivity and thickness of the different layers. By using conventional GIS method, the spatial distribution maps for fracture zone resistivity and thickness zones were prepared. Integration of the said themes was done it in GIS. First layer fracture zone thickness and resistivity maps were overlaid and the polygon combinations were brought out. 9 combinations of 1LR-1LT, 1LR-1MT, 1LR-1HT, 1MR- 1LT, 1MR-1MT, 1MR-1HT, 1HR-1LT, 1HR-1MT and 1HR-1LT were arrived, and designated as output map 1. This map shows that the shallow depth groundwater combination of (1LR-1HT and 1LR-1MT) covers an area of 50.39 Km2 and 28.73 Km2. Similarly, the second fracture zone thickness and resistivity maps were superposed. The result map designated as output map 2 gives a combination of 9 polygons of 2LR-2LT, 2LR-2MT, 2LR-2HT, 2MR-2LT, 2MR-2MT, 2MRª2HT, 2HR-2LT, 2HR-2MT and 2HR-2LT. This map shows that the deeper depth groundwater combinations of (2LR-2HT and 2LR-2MT) for deep groundwater zones were delineated and occupies an area 00.16 Km2 and 13.10 Km2.
8 illus, 4 tables, 11 ref
Choyal Y;Gupta L;Deshpande P;Maheshwari K P; Mittal K C;Bapna S C
015709 Choyal Y;Gupta L;Deshpande P;Maheshwari K P; Mittal K C;Bapna S C (School of Physics, , Ahilya Vishwavidyalaya, Email: firstname.lastname@example.org) : Development of a 2 MW relativistic backward wave oscillator. Pramana J Phys 2008, 71(6), 1301-10.
A high power relativistic backward wave oscillator (BWO) experiment is reported. A 230 keV, 2 kA, 150 ns relativistic electron beam is generated using a Marx generator. The beam is then injected into a hollow rippled wall metallic cylindrical tube that forms a slow wave structure. The beam is guided using an axial pulsed magnetic field having a peak value 1 T and duration 1 ms. The field is generated by the discharge of a capacitor bank into a solenoidal coil. A synchronization circuit ensures the generation of the electron beam at the instant when the axial magnetic field attains its peak value. The beam interacts with the SWS modes and generates microwaves due to Cherenkov interaction. Estimated power of 2 MW in TMv01D mode is observed.
9 illus, 19 ref
011434 Umezu M (Astronomical Institute, Graduate School of Science, Tohoku Univ, Sendai 980-8578, Japan, Email: email@example.com) : Instability of a convection zone with large gradient of the mean molecular weight. Bull Astr Soc India 2009, 37(3-4), 91-107.
An inefficient convective solution with non - negligible gradient of the mean molecular weight was discovered by extending the mixing-length theory of convection (Umezu & Nakakita 1988). This solution is unstable, but becomes stable if the radiative heat loss from the convective element is negligible. However, since the size of the convective element necessary to stabilize this solution is larger than the stellar radius by several orders, this inefficient convection solution never becomes stable. If the radiative heat loss is neglected, the zone with this inefficient convection solution resembles the Ledoux semicon-vection zone. Hence this study might show another reason against the Ledoux semiconvection zone.
8 illus, 1 table, 39 ref
Saikia D J;Jamrozy M
011433 Saikia D J;Jamrozy M (NO, National Centre for Radio Astrophysics, Post Bag 3, Ganeshkhind, Pune-411 007, Email: firstname.lastname@example.org) : Recurrent activity in active galactic nuclei. Bull Astr Soc India 2009, 37(3-4), 63-89.
There has been a growing body of evidence to suggest that AGN activity, which is powered by mass accretion on to a supermasive black hole, could be episodic, although the range of time scales involved needs to be explored further. The structure and spectra of radio emission from radio galaxies, whose sizes range up to ~ 5 Mpc, contain information on the history of AGN activity in the source. They thus provide a unique opportunity to study the time scales of recurrent AGN activity. The most striking examples of recurrent activity in radio galaxies and quasars are the double-double or triple-double radio sources which contain two or three pairs of distinct lobes on opposite sides of the parent optical object. Spectral and dynamical ages of these lobes could be used to constrain time scales of episodic activity. Inverse-Compton scattered cosmic microwave background radiation could in principle probe lower Lorentz-factor particles than radio observations of synchrotron emission, and thereby reveal an older population. We review briefly the radio continuum as well as molecular and atomic gas properties of radio sources which exhibit recurrent or episodic activity, and present a few cases of quasars which require further observations to confirm their episodic nature. We also illustrate evidence of episodic AGN activity in radio sources in clusters of galaxies.
8 illus, 12 tables, 172 ref
Safonova M;Shalima P;Murthy J
011432 Safonova M;Shalima P;Murthy J (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: email@example.com) : TAUVEX flight calibrations: plans and challenges. Bull Astr Soc India 2009, 37(1-2), 23-43.
The operational tasks for the Performance Verification (PV) and calibration phase in the first year of TAUVEX operation are presented. The new challenges regarding the possible reduction in sensitivity are outlined and are reflected in the specialized plan for first few months of the mission. The calibration operations will be extended into the first year, in parallel to an unprecedented deep exposure of the celestial poles. The preliminary zero-points of the instrumental photometric system, in AB and Vega-based magnitude systems, are calculated for pre-ground calibrations data as well as for the updated results. For flux calibration, the effective wavelengths, bandwidths and conversion factors are calculated for both pre-ground and updated values. These conversion factors are to be used for converting the TAUVEX count rates to flux and UV luminosity of the sources.
1 illus, 11 tables, 9 ref
Munshi R;Prasad B R;Murthy J
011431 Munshi R;Prasad B R;Murthy J (Physics and Meterology Dep, Indian Institute of Technology, Kharagpur-721 302, Email: firstname.lastname@example.org) : Design and analysis of an FUV spectrograph for a small satellite. Bull Astr Soc India 2009, 37(1-2), 11-21.
The Halo Ultraviolet Explorer (HUE) is a payload aimed at studying the diffuse far ultraviolet sky over a bandpass of 800 - 1200 A. The novel features of HUE include a large effective collecting area (254 cm2) and fast (f/2.2) optics in a compact design optimized for a standard small satellite bus. We have investigated two different models, each with an 18 cm off-axis parabolic primary mirror, but one with an additional folding mirror to decrease the total length of the spectrograph. The spectrograph slit is dumbbell shaped maximizing the spectral resolution in the centre of the slit while increasing the sensitivity to diffuse sources at the edges. The primary scientific goal of the mission is to investigate the distribution of OVI in the Galactic halo. This line is a sensitive indicator of the hot gas in the interstellar medium and is critical in understanding the dynamics and energetics of the Galaxy.
8 illus, 5 tables, 4 ref
Green D A
011430 Green D A (NO, , Astrophysics Group, Govendish Laboratory, 19 J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom, Email: D.A.Green@mrao.cam.ac.uk) : Revised galactic supernova remnant catalogue. Bull Astr Soc India 2009, 37(1-2), 45-61.
A revised catalogue of 274 Galactic supernova remnants (SNRs) is presented, along with some simple statistics of their parameters. It is shown that the remnants that have recently been identified are generally faint, as is expected from the selection effects that apply to the identification of remnants.
3 illus, 34 ref
Deb S;Tiwari S K;Singh H P;Seshadri T R; Chabye U S
011429 Deb S;Tiwari S K;Singh H P;Seshadri T R; Chabye U S (Physics & Astrophysics Dep, Delhi Univ, Delhi-110 007, Email: email@example.com) : Photometry of the δ scuti star HD 40372. Bull Astr Soc India 2009, 37(3-4), 109-23.
Presents B band photometry of the δ Scuti star HD 40372 using the ARIES three channel fast photometer attached to the 104-cm Sam-purnanand telescope in high-speed photometric mode. The star was observed for ~ 5 hours on December 13, 2008. Based on the high quality photometric data, we have done period analysis by various periodogram analysis techniques. The best estimate of the period is found to be ~ 0.067 days. With this period and the other stellar parameters determined from uvby β photometry available in the literature, we have calculated the Q value for the star. Comparison of this Q value with that determined from the model calculations shows that the star is pulsating in pa mode with l = 2.
9 illus, 2 tables, 137 ref
Anand M Y;Kagali B A;Murthy J
011428 Anand M Y;Kagali B A;Murthy J (Physics Dep, Bangalore Univ, Bangalore-560 056) : Bubble nebula using IUE high resolution spectra. Bull Astr Soc India 2009, 37(1-2), 1-10.
Analyses IUE high resolution spectra of the central star (BD+602522) of the Bubble nebula. Discusses velocities of the different regions along the line of sight to the bubble. It was found that the Bubble nebula is younger (by a factor of 100) than the exciting star suggesting that either the bubble is expanding into an inhomogeneous interstellar medium or that the mechanics of the stellar wind are not fully understood.
6 illus, 5 tables, 18 ref
Fogedby H C
010427 Fogedby H C (Physics and Astronomy Dep, Aarhus Univ, Ny Munkegade, DK-8200, Aarhus C, Denmark and Niels Bohr Institute, Copenhagen Univ, DK-2100, Copenhagen, Denmark, Email: firstname.lastname@example.org) : Patterns in the Kardar-Parisi-Zhang equation. Pramana J Phys 2008, 71(2), 253-62.
Review a recent asymptotic weak noise approach to the Kardar-Parisi-Zhang equation for the kinetic growth of an interface in higher dimensions. The weak noise approach provides a many-body picture of a growing interface in terms of a network of localized growth modes. Scaling in 1d is associated with a gapless domain wall mode. The method also provides an independent argument for the existence of an upper critical dimension.
4 illus, 9 ref
009383 Nath B (NO, Raman Research Institute, C V Raman Avenue, Sadashivnagar, Bangalore-560 080, Email: email@example.com ) : Biggest explosions in the universe. Resonance 2009, 14(10), 989-95.
Gamma ray bursts - which are first detected in energetic gamma rays and which then glow in X-ray, visible and radio wavelengths - are the result of the biggest explosions in the universe. Astronomers wonder what causes these violent events, and some of their ideas are discussed.
Das S;Jain P;Ralston J P;Saha R
009382 Das S;Jain P;Ralston J P;Saha R (Astrophysical Sciences Dep, Princeton Univ, New Jersey 08544, USA, Email: firstname.lastname@example.org) : Dynamical mixing of light and pseudoscalar fields. Pramana J Phys 2008, 70(3), 439-56.
Solve the general problem of mixing of electromagnetic and scalar or pseudoscalar fields coupled by axion-type interactions Lint = gΦΦε
5 illus, 26 ref
008348 Torabi G (Geology Dep, Isfahan Univ, Isfahan (Iran), Email: Torabighodrat@yahoo.com) : Fault-related geohazards in Iran. Ultra Scient phys Sci 2009, 21(2), 259-68.
Geologically, Iran is the land of faults. Except in northern part, the Iran is an arid region and for the centuries the Iranians selected the place of springs for living and village or city establishing. But most of these places are fault-related and faults supply the groundwaters. There are different geohazards in Iran that are in relation with faults: 1 - Earthquake, 2- Ophiolites and asbestos minerals, 3-Radioactive, toxic, and heavy metal elements mineralization, 4- Radon and CO2 releasing.
6 illus, 1 table, 16 ref
Pattnaik S;Kamila S K;Roy G S
008347 Pattnaik S;Kamila S K;Roy G S (NO, , Plot No-6, Budheswari Colony, Bhubaneswar-751 006) : Visual binary stars-calculation of orbital parameters of WDS 04374-0951 & WDS 18384+0850. Ultra Scient phys Sci 2009, 21(2), 365-74.
A Study of Binary Stars - its Detection, Resolution & Classification has been undertaken using general diffraction integral. The calculation for the orbits of visual binary stars: WDS04374-0951 & WDS 18384+0850 have been undertaken along with the determination of the mass, dynamical parallax and ephemerid by using data available in ADS.
5 illus, 3 tables, 23 ref
Kumaravel S;Gurugnanam B;Suresh M;Senthil Kumar M;Sivanatarajan G
008346 Kumaravel S;Gurugnanam B;Suresh M;Senthil Kumar M;Sivanatarajan G (Earth Sciences Dep, Annamalai Univ, Annamalai Nagar, Chidambaram, Tamil Nadu, Email: email@example.com) : Demarcate groundwater favorable zones through gepohysical and GIS study in Parivillikottai Firka, Tuticorin District, Tamilnadu, India. Ultra Scient phys Sci 2009, 21(2), 375-86.
GIS is a powerful tools in analysing the multiple thematic maps at a time. G1S analysis is carried out in the present study to locate favorable shallow and deep groundwaler bearing zones. To do this subsurface investigation and its interpretation were carried out through geophysical survey. Fifteen vertical electrical soundings (VES) survey were carried out in the study area. The field data were interpreted by RESIST software to determine the resistivity and thickness of the different layers. By using conventional GIS method, the spatial distribution maps for fracture zone resistivity and thickness zones were prepared. Integration of the said themes was done it in GIS. First layer fracture zone thickness and resistivity maps were overlaid and the polygon combinations were brought out. 9 combinations of 1LR-1LT, 1LR-1MT, 1LR-1HT, 1MR-1LT, 1MR-1MT, 1MR-1HT, 1HR-1LT, IHR-IMTand 1HR-1LT were arrived, and designated as output map 1. This map shows that the shallow depth groundwater combination of (ILR-1HT and 1LR-1MT) covers an area of 50.39 Km2 and 28.73 Km2. Similarly, the second fracture zone thickness and resistivity maps were superposed. The result map designated as output map 2 gives a combination of 9 polygons of 2LR-2LT, 2LR-2MT, 2LR-2HT, 2MR-2LT, 2MR-2MT. 2MR-2HT, 2HR-2LT, 2HR-2MT and 2HR-2LT. This map shows that the deeper depth groundwater combinations of (2LR-2HT and 2LR-2MT) for deep groundwater zones were delineated and occupies an area of 3.16 Km2 and 13.10 Km2.
8 illus, 4 tables, 11 ref
Sridhar A R;Tewari H C;Vijaya Rao V;Satyavani N;Thakur N K
006118 Sridhar A R;Tewari H C;Vijaya Rao V;Satyavani N;Thakur N K (Nationla Geophysical Research Institute, Uppal Road, Hyderabad-500 007, Email: firstname.lastname@example.org) : Crustal Velocity Structure of the Narmada-Son Lineament along the Thuadara-Sendhwa-Sindad Profile in the NW Part of Central India and its Geodynamic Implications. J Geol Soc India 2007, 69(6), 1147-60.
A five-layered crusta! model with 5.9-6.2, 6.0, 6.3, 6.6 and 7.0 kms-1 velocities is derived with seismic refraction/wide-angle reflection data along the Thuadara-Sendhwa-Sindad profile in central India. The profile traverses across the western part of the Narmada-Son lineament in the N-S direction. The data are subjected to 2-D forward modelling using-both travel times and amplitudes. Refracted waves (Pn) from the Moho observed as first arrivals at a distance of about 200 km are used to derive the upper mantle velocity of 8.1 kms-1. The Moho is well constrained both from the Pn and wide-angle reflections from four shot points. The main features of the velocity structure is the delineation of a low velocity layer (6.0 kms-1) in the upper crust and a 12-16 km thick high velocity (7.0 kms-1) layer at the base of the crust. The high velocity lower crustal layer, representing the magmatic underplating in the region, may be related to the formation of the Narmada Basin and the Deccan volcanic episode. The Deccan volcanism may be a consequence of the Reunion mantle plume activity. The crustal thickness varies between 37 and 43 km along the profile and the thickest crust is found between the Narmada and Tapti rivers. The gravity model constrained from the seismic velocity structure corroborates the crustal structure. Deep-seated faults responsible for the evolution of Narmada Basin are inferred from the present study.
10 illus, 48 ref
Rajesh E;Anbarasu K;Rajamanickam G V
006117 Rajesh E;Anbarasu K;Rajamanickam G V (Earth Sciences Dep, Tamil Univ, Thanjavur-613-413, Email: email@example.com) : Grain size distribution of silica sands in and around marakkanam coast of Tamil Nadu. J Geol Soc India 2007, 69(6), 1361-8.
Silica sand samples of Marakkanam region have been studied to understand the textural variation of the sediments. The study area has been divided into three groups, namely, Mudaliyarkuppam, Kakapallam and Agaram (Pallampakkam, Vadaagaram and Urani) on the basis of relief. Frequency curves of the silica sands in the study area show a polymodal distribution in Mudaliyarkuppam and Agaram group and bimodal distribution at Kakapallam Group. Mudaliyarkuppam samples are coarser to medium grained, poorly sorted, fine to strongly fine skewed and platy to mesokurtic in nature. On the other hand, Kakapallam Group is represented by its coarser size, very well sorted; fine skewed and leptokurtic in nature. Agaram Group is characterized by medium sands, moderately sorted, fine skewed to nearly symmetrical skewed and mesokurtic. Bivariant plots show a distinct grouping with an influence of offshore environment at Mudaliyarkuppam Group and, channel bar and dune environment at Kakapallam and Agaram Group.
6 illus, 1 table, 20 ref
Gholap S S;Patil M B;Kank V D;Ranade A S; Gadegaonkar G M;Gulavane S U;Karambele N R
006116 Gholap S S;Patil M B;Kank V D;Ranade A S; Gadegaonkar G M;Gulavane S U;Karambele N R (Animal Nutrition Dep, Bombay Veterinary College, Parel, Mumbai-400 012) : Effects of prebiotics (MOS) as growth promoter in broilers. J Bombay Vet Coll 2009, 17(1), 63-5.
The experiment was conducted to evaluate the effects of prebiotics (MOS) and antibiotic as feed additives on performance of broilers. Two hundred day old "Marshal FG " broiler chicks were divided into four equal groups viz. A, B, C and D. Group A was kept as control. The birds from group B received diets with prebiotic Mannan Oligosaccharide (MOS) @ 250 g/ton of feed. The birds from group C received diet with feed additive Bacitracin Methylene Disalicylate (BMD) @ 200 g/ton of feed. Group D received diet with feed additive Virginiamycin @ 500g/ton of feed. Effect of feed treatments on live weights, gain in weights and feed consumption of birds was statistically non significant. The feed conversion ratios (FCR) for groups A to D were 2.124, 1.972, 2.022 and 2.188, respectively, which revealed significant difference among the treatments. Nitrogen retention percent was higher for all the treatment groups than control group. Group C recorded higher net profit per kg followed by group B, A and D, respectively. It is concluded that prebiotic (MOS) and BMD can be used in the diets as growth promoters for better production performance of broilers in terms of growth, FCR and economics of production.
1 table, 6 ref
Sharma N L;Kuniyal J C;Mahavir Singh;Negi A K;Kesar Singh;Sharma P
003045 Sharma N L;Kuniyal J C;Mahavir Singh;Negi A K;Kesar Singh;Sharma P (NO, Govt Post Graduate College, Kullu-175 101, Email: firstname.lastname@example.org) : Number concentration characteristics of ultrafine aerosols (atmospheric nanoparticles / aitken nuclei) during 2008 over western Himalayan region, Kullu-Manali, India. Indian J Radio Space Phys 2009, 38(6), 326-37.
The ultrafine particles of three sizes 200, 30 and 10 A [20 nm (aitken mode), 3 nm, 1 nm (nucleation mode / nano particles)] were monitored with water based condensation particle counter during January-December 2008 at Mohal in Kullu-Manali area of North western Himalayas. The results indicate that diurnal pattern has faint bimodal structure with two peaks, one in morning and other in evening but is not as distinct as found in plains. There is rather constant particle density pattern consistent with vehicular movement from morning till evening. This may also be due to abnormally large bursts of particles (nucleation bursts) which are found to be more in summer than winter, more during sunrise and less during afternoon. The weak nucleation bursts are found to be frequent throughout the year than very strong nucleation bursts which are mostly found during months of June, July and August. The monthly 24 h average density gradually picks up from January, increases rapidly in summer months and then decreases in winter. The density is more in summer than in winter, a trend opposite to plains, may be due to development of warm thermal layer on valley floor while cold layer developed along snowy hilltops in winter leading to convection of fine particles up the slopes of valley during daytime. The relatively more value in September and October is due to month long international Dussehra festival in the valley and unexpected lower values in November and December may be due to low local as well as tourist traffic flow; washout/rainout effects; and higher inversion layer. The vehicular survey conducted agrees well with diurnal, monthly as well as yearly averaged diurnal variation of fine particles. The annual average of 24 h average value of ultrafine particles of three size range is 18045±1212, 16811±2790, and 15407±3109 N cm-3, respectively. The comparison with earlier results shows significant increase of ultrafine particles indicating impact of vehicular increase in the region.
Ram Prakash;Singh M K;Gupta D D
003044 Ram Prakash;Singh M K;Gupta D D (Physics Dep, Bipin Bihari PG College, Jhansi-284 001) : Relative effectiveness of plasmaspheric hiss and VLF hiss in the inner belt energetic electron precipitation. Indian J Radio Space Phys 2009, 38(5), 254-9.
Relative effectiveness of plasmaspheric hiss and VLF hiss in the inner belt energetic electron precipitation has been studied. The results show that plasmaspheric hiss can induce significant precipitation of electrons by causing small changes in their energy whereas in case of VLF hiss, nearly ten times higher energy changes are required for similar precipitation. The minimum pitch angle αm corresponding to peak energy change varies with L-value in the same fashion as the minimum wave length (λm) corresponding to peak energy emission varies with temperature T in case of black body radiation. The results, further, hint that the plasmaspheric hiss is more effective in energetic electron precipitation towards the inner edge (L≈ 1.2) of inner radiation belt, which is in good agreement with the findings of earlier studies.
Ogolo E O;Falodun S E;Oluyamo S S;Nymphas E F
003043 Ogolo E O;Falodun S E;Oluyamo S S;Nymphas E F (Physics Dep, Federal University of Technology, Akure, Email: email@example.com) : Analysis of data on net longwave, shortwave and global radiation during transition period in a tropical station in Southwestern Nigeria. Indian J Radio Space Phys 2009, 38(6), 347-52.
Examines the distribution of surface radiation balance components measured during the Nigerian Micrometeorological Experiment (NIMEX-1). A field study was conducted to measure surface heat fluxes in the boundary layer during the transition period which marks the end of dry season and the onset of wet season (15 February and 10 March 2004) in Southwestern part of Nigeria. Regression equations were obtained using daily average values and hourly mean values between net shortwave and net longwave radiation, respectively with the global radiation. Higher correlations with low standard error of measurement were obtained for daily mean values than hourly mean values. It was also observed that the peak value of each radiation during the period occurred for two hours in the afternoon on an average as expected.
Kane R P
003042 Kane R P (NO, Instituto Nacional de Pesquisas Espaciais-INPE, C P 515, Sao Jose' dos Campos, 12245-970 SP, Brazil, Email: firstname.lastname@example.org) : Ozone depletion, worst not yet over. Indian J Radio Space Phys 2009, 38(6), 313-6.
The ozone depletion which started in late 1970s, reached a maximum level (minimum ozone content) in 1993 and thereafter a partial recovery seemed to have occurred up to 2002. But that was a false signal. From 2003 onwards, there seems to have a relapse and the level has been low even in 2009 implying that a permanent damage might have occurred.
Kane R P
003041 Kane R P (NO, Instituto Nacional de Pesquisas Espacias - INPE, Caixa Postal 515, 12201-970 - Sao Jose dos Campos, SP, Brazil, Email: email@example.com) : Variations of geomagnetic Dst, auroral indices and cosmic ray intensity during 28-31 Oct 2003 Halloween events. Indian J Radio Space Phys 2009, 38(5), 245-53.
During 28-31 Oct 2003, there was intense interplanetary storm activity (Halloween events). A major storm started at about 0400-0600 hrs UT on 29 Oct 2003, reflected in extreme values of interplanetary parameters and geomagnetic index Dst. While few hours preceding 0400 hrs UT, it was essentially quiet but the auroral indices AL, AU, AE were not quiet and showed moderate increases. Thus, at least for this gigantic super fast storm (velocity of the solar wind disturbance exceeding 2000 kms-1), auroral indices seemed to be precursors with an antecedence of a few hours. This needs to be checked for very strong storms in future, probably after 2010, when cycle 24 sunspot activity will be in full swing.
Dharanibai G;Alex Z C
003040 Dharanibai G;Alex Z C (School of Electrical Sciences, VIT University, Vellore-632 014, Email: firstname.lastname@example.org) : ANN technique for the evaluation of soil moisture over bare and vegetated fields from microwave radiometer data. Indian J Radio Space Phys 2009, 38(5), 283-8.
Retrieving information from remotely sensed data is an important task. In the present work, data of L band microwave radiometer has been used to collect the brightness temperature over bare and vegetated fields in two polarizations at different moisture levels. Artificial neural network (ANN) trained with Levenberg-Marquardt algorithm has been used to determine soil moisture from brightness temperatures measured by microwave radiometry. ANN are trained to evaluate the moisture content in the range 0 - 36% from different sets of data of bare and vegetated fields. Properly trained feed-forward neural network with Levenberg-Marquardt algorithm predicted soil moisture content with less mean absolute error.
De B K;De S S;bandyopadhyay B;Paul S;Barui S; Haldar D K
003039 De B K;De S S;bandyopadhyay B;Paul S;Barui S; Haldar D K (Physics Dep, Tripura University, Tripura (West), Suryamaninagar-799 130, Email: email@example.com) : Some studies of solar flare effects on the propagation of sferics and a transmitted signal. Indian J Radio Space Phys 2009, 38(5), 260-5.
Apart from diurnal and seasonal variations, integrated field intensity of sferics (IFIS) exhibits characteristic variations in relation to various geophysical and solar events like geomagnetic storms, meteor showers, solar X-ray flares and solar radio emission. Continuous monitoring of IFIS at frequencies 1, 3, 6, 9 and 12 kHz from Agartala (latitude 23°N) are being made over the last several years. The analyses of some preliminary observations in relation to solar flares are reported in the paper. Solar flare effects on the propagation of transmitted signals at 16.3 kHz recorded in Kolkata (latitude 22.56°N) during November 2004 have also been presented.
Das S S
002028 Das S S (Geological Studies Unit, Indian Statistical Institute, 203 B. T. Riad, Kolkata-700 108, Email: firstname.lastname@example.org) : Gastropod diversity patterns and evolutionary tempo during the early eifting phase (Jurassic) of the kutch basin. J Palaeont Soc India 2008, 53(1), 9-18.
The Kutch sea formed as a result of Gondwana fragmentation about 170 million years ago. This newly opened up sea-way between Africa and India provided new habitats for the immigrant faunas which invaded the Kutch Basin. They underwent rapid speciation events as clearly evident from diversity patterns of different taxa of Kutch. The present paper deals with the diversity patterns and evolutionary tempo shown by the gastropods during the Late Bathonian to the Oxfordian. Archacogastropod community is the most diverse group in Kutch (Das et al., 1999, 2005; Jaitly et al., 2000; Das, 2004), showing strong Tethyan affinity, especially with Europe at genus level, but display stunning endemism at species level. The great diversity and abundance of the Kutch species can be explained by the range of expansion of the genera from their ancestral area. Mass migration or colonization of the European forms into Kutch also coincided with a global marine transgression. The extensive shallow epicontinental sea with a large habitable area and subtropical palaeolatituidinal position of Kutch are two other extrinsic factors for the great diversity.
6 illus, 1 table, 56 ref
001083 Nath B (Astrophysics Group, Raman Research Institute, Bangalore-560 080, Email: email@example.com) : Hubble's menagerie of galaxies. Resonance 2009, 14(3), 226-35.
Hubble designed a classification scheme of galaxies based on their appearances. It was such a robust scheme that it continues to be one of the basic tools of modern astronomy, and motivates astronomers to look for connections between different types of galaxies.
3 illus, 1 ref
Bagla J S
001082 Bagla J S (NO, Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad-211 019, Email: firstname.lastname@example.org) : Hubble, hubble's law and the expanding universe. Resonance 2009, 14(3), 216-25.
Studies Hubble's law and discuss how it relates with models of the universe. Also gives a historical perspective of the discoveries that led to the Hubble's law.
1 illus, 16 ref
Santosh Kumar;Pal J
020489 Santosh Kumar;Pal J (PG Studies and Research in Physics and Electronics Dep, R.D. Univ, Jabalpur-482 001, Email: email@example.com) : SEPs associated CMEs affecting near earth environment. Indian J Phys 2008, 82(10), 1255-63.
The geoeffectiveness of seventy-five Solar Energetic Particles (SEPs) effective coronal mass ejection (CMEs) have been investigated during the period 1997-2505. The seventy-five events have been classified into different groups according to proton intensity and their geospatial response have been examined. The geomagnetic storms are measured with the minimum Dst value occurring within a day or first half of next day after the SEP maximum during the event. It is observed that higher SEP intensity is better correlated with Dst than the lower proton intensity; so that, higher SEP intensity leads to intense geomagnetic storms (GMSs); and, lower proton intensity to moderate GMSs. It is observed that there is no significant correlation between proton intensity and flare size in terms of X- ray peak flux. The source location is also one of the important parameters in deciding the geoeffectiveness of SEP effective CMEs i.e., the nature of GMSs. It is further observed that 2001 and 2003 are most peculiar years to produce extreme (R5) and severe (R4) radio blackouts during the period of investigation. Furthermore, the initial CMEs velocity related to higher proton intensity is significantly correlated with Dst than the lower proton intensity.
6 illus, 1 table, 10 ref
Sridharan M;Samuel Selvaraj R
019386 Sridharan M;Samuel Selvaraj R (Magnetic Observatory, Indian Institute of Geomagnetism, Pondicherry University Campus, Pondicherry-605 014, Email: firstname.lastname@example.org) : Multi dimensional scaling of geomagnetic Sq (H) variations. Indian J Radio Space Phys 2009, 38(3), 165-73.
The dominant relationship in respect of geomagnetic solar quiet day variations (Sq) among the six Indian geomagnetic observatories is analysed by employing multidimensional scaling. This is a powerful technique for data analysis to identify the proximity and dominance relationship between data points of different classes.
Singh K A P;Van Doorsselaere T
019385 Singh K A P;Van Doorsselaere T (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: email@example.com ) : New avenues in solar physics science with hinode. Curr Sci 2008, 95(2), 159-61.
Hinode is a very potential mission to unravel the intricacies of the Sun from space. It helps solving the long awaiting 'coronal heating conundrum' and understanding the mysterious solar corona by recent discoveries of ubiquitous waves, anemone jets and outflows. Hmode findings proved the presence of waves of sufficient strength to power the solar wind which buffets the Earth's magnetic field and causes the space weather events.
3 illus, 15 ref
Santosh Kumar;Pal J;Raizada A
019384 Santosh Kumar;Pal J;Raizada A (Physics & Electronics Dep, R. D. University, Jabalpur (M.P.), Email: s_ firstname.lastname@example.org) : Properties of SEPs effective CMEs during solar cycle 23. Indian J Radio Space Phys 2009, 38(3), 129-33.
Seventy five large solar energetic particle (LSEP) events of different groups of proton intensity have been investigated during 1997-2005. It is observed that proton intensity increases linearly with increase in velocity of SEPs effective coronal mass ejections (CMEs). Further, for proton intensity I>350 pfu, most of the SEPs effective CMEs are associated with X class of X-ray flares; whereas, for proton intensity I< 350 pfu, the SEPs effective CMEs are associated mainly with M and C class of X-ray flares. Furthermore, most of the CMEs are of halo type and occur mostly in western hemisphere for proton intensity I>350 pfu; whereas, for proton intensity I<350 pfu, CMEs observed in the eastern hemisphere are equally important. The association of SEPs effective CMEs has been observed better for longer wavelength, i.e. Decameter - Hectometer (DH) Type II radio bursts than shorter wavelength, i.e. metric (m) Type II radio bursts.
Sanalkumaran Nair V;Prabhakaran Nayar S R
019383 Sanalkumaran Nair V;Prabhakaran Nayar S R (Physics Dep, V.T.M. N.S.S. College, Dhanuvachapuram, Thiruvananthapuram-695 122, Email: email@example.com) : Features of long term evolution of solar wind and IMF and their signature on geomagnetic activity. Indian J Radio Space Phys 2009, 38(3), 134-7.
The geomagnetic activity is mainly controlled by variations in the solar wind and interplanetary magnetic field (IMF) features. The solar wind data available during 1965-2004 has been utilized to study large scale features in interplanetary medium and their signature on geomagnetic activity. The solar wind plasma, IMF and geomagnetic activity are found to evolve with the phase of solar cycle. The evolution and role of solar wind streams and IMF field strength (B) in shaping long term features of planetary magnetic activity index (Ap) index have been studied. The high speed streams are caused mainly by the increase in coronal hole activity around the declining phase of solar cycle and by the presence of large number of coronal transients around solar maximum. Association between coronal holes and geomagnetic activity is clear from the simultaneous presence of high negative correlation between solar wind velocity (Vsw) and density (n) and the enhancement in geomagnetic activity during declining phase of solar cycle. During this period, Vsw and Ap index also exhibit good correlation. Around solar maximum periods, good correlation is found between B and Ap index. These results suggest that Vsw has a major role in deciding the geomagnetic activity around declining phase and IMF magnitude has a major role in deciding geomagnetic activity around solar maximum.
Rosalind Ezhil K.
019382 Rosalind Ezhil K. (NO, , Rosalind Ezhil K. (S. Ramaseshan Fel-low) lives at 122, 3rd Main, Dollar Colony, RMV 2nd Stage, 1st Block, Bangalore-560, Email: firstname.lastname@example.org) : Collimated particle beams from pulsars. Curr Sci 2008, 95(3), 308-10.
2 illus, 5 ref
Lakshmi Narayanan V;Gurubaran S;Emperumal K
019381 Lakshmi Narayanan V;Gurubaran S;Emperumal K (Equatorial Geophysical Research Lab, Indian Institute of Geomagnetism, Tirunelveli-627 011) : Imaging observations of upper mesospheric nightglow emissions from Tirunelveli (8.7°N). Indian J Radio Space Phys 2009, 38(3), 150-8.
An all-sky airglow imager was installed at the equatorial site Tirunelveli (8.7°N, 77.8°E geographic; 1.34°N magnetic dip) during January 2007 to study the small-scale dynamics occurring in the mesosphere-lower thermosphere (MLT) region. The instrument details are presented in the paper along with methods of information retrieval from the recorded data. The presence of a variety of small-scale mesospheric dynamical events, observed with the instrument, is demonstrated. Preliminary results on the observed features, viz. the quasi-monochromatic gravity waves and instability features, such as ripples and mesospheric bores, are presented.
De S S;De B K;Adhikari S K;Bandyopadhyay B; Paul S;Haldar D K;Guha A
019380 De S S;De B K;Adhikari S K;Bandyopadhyay B; Paul S;Haldar D K;Guha A (Centre of Advanced Study in Radio Physics and Electronics, University of Calcutta, Kolkata-700 009, Email: email@example.com) : Studies on sferics over Kolkata in relation to rainy and winter seasons. Indian J Radio Space Phys 2009, 38(3), 143-9.
The VLF spectral characteristics of the sferics over Kolkata (22.56°N, 88.5°E) are studied in relation to the rainy and winter seasons. The nature of sferics during rainy and winter seasons is determined for different times of the day. The recorded data of sferics from Kolkata exhibit many interesting monitoring possibilities due to the involvement of the characteristics of atmospheric and ionospheric parameters. The recorded sferics exhibit diurnal variation of electron density of the lower ionosphere. Many interesting features are observed including sunrise and sunset effects.
Chatterjee A K;Bari W;Choudhury A K
019379 Chatterjee A K;Bari W;Choudhury A K (NO, Indian Centre for Space Physics (Malda Branch), Malda-732 101, Email: firstname.lastname@example.org) : Anomalous behavior of D-layer formation time of the ionosphere due to earthquake. Indian J Radio Space Phys 2009, 38(3), 138-42.
The very low frequency (VLF) data for over three months (May to July 2008) using Gyrator II loop antenna has been analyzed in the present study. The significant anomalies of D-layer formation time of the ionosphere are observed during sunrise. These anomalies are observed only before, during and after the earthquakes, which took place in the neighboring region. The anomalies were also observed in sunrise terminator time during seismically active days. These abnormal behavior may be due to the lithosphere - ionosphere coupling. These anomalies may be a precursor of earthquake.
Wang S;Deng Y;Jain R;Yurchyshyn V;Wang H;Liu Y;Yang Z
018365 Wang S;Deng Y;Jain R;Yurchyshyn V;Wang H;Liu Y;Yang Z (Astronomy Dep, Beiing Normal University, Beijing, 100 875, China, Email: email@example.com) : Evolution of vector magnetic field associated with major flares in NOAA AR10656. J Astrophys Astr 2008, 29(1-2), 57-61.
Study the evolution of vector magnetic field of AR 10656 by using the observations of Huairou Solar Observing Station (HSOS, China) and Big Bear Solar Observatory (BBSO, USA). The magnetic flux emergence and cancellation, and thus, magnetic non-potential changes, are associated with the major flares in this active region. Compared with some other super-active regions, the evolution of magnetic morphologies and non-potentialities are relatively gradual, and thus the energy transportation and release are relatively slow. This gradual process may result in the recurrent flares of AR 10656.
3 illus, 13 ref
018364 Wang J (National Astronomical Observatories, Chinese Academy of Science, Beijing 100012, China, Email: firstname.lastname@example.org) : Solar flare associated magnetic changes in solar active regions. Asian J Phys 2008, 17(3-4), 347-62.
Solar flare associated magnetic changes in solar active regions is a long-lasting issue in solar physics. The relevant observational studies have been done in three inter-connected directions: (1) the pre-flare magnetic configuration and evolution, (2) the rapid magnetic changes in the course of flares, and (3) the flare-induced signals in polarization measurements. The importance of these studies is to examine our physical understanding on the flare phenomenon which takes place in a wide range of astrophysical subjects. Although it is well established that flares come from the magnetic energy release in strong magnetic fields of the Sun and stars, current theoretical models are still far from being confronting the detailed observations. Study reviews some key advances in the relevant studies and suggest possible directions for the future.
7 illus, 1 table, 83 ref
018363 Vijayan S (Institute of Remote Sensing, Anna Univ, Chennai, Email: email@example.com) : Utilization of GPS satellites for precise irradiation measurement and monitoring. J Astrophys Astr 2008, 29(1-2), 359-61.
Precise measurement of irradiance over the earth under various circumstances like solar flares, coronal mass ejections, over an 11-year solar cycle, etc. leads to better understanding of Sun-earth relationship. To continuously monitor the irradiance over earth-space regions several satellites at several positions are required. For that continuous and multiple satellite monitoring we can use GPS (Global Positioning System) satellites (like GLONASS, GALILEO, future satellites) installed with irradiance measuring and monitoring instruments. GPS satellite system consists of 24 constellations of satellites. Therefore usage of all the satellites leads to 24 measurements of irradiance at the top of the atmosphere (or 12 measurements of those satellites which are pointing towards the Sun) at an instant. Therefore in one day, numerous irradiance observations can be obtained for the whole globe, which will be very helpful for several applications like Albedo calculation, Earth Radiation Budget calculation, monitoring of near earth-space atmosphere, etc. Moreover, measuring irradiance both in ground (using ground instruments) and in space at the same instant of time over a same place, leads to numerous advantages. That is, for a single position we obtain irradiance at the top of the atmosphere, irradiance at ground and the difference in irradiance from over top of the atmosphere to the ground. Measurement of irradiance over the atmosphere and in ground at a precise location gives more fine details about the solar irradiance influence over the earth, path loss and interaction of with the atmosphere.
Verma S R;Chaudhary D
018362 Verma S R;Chaudhary D (Physics Dep, D.B.S. (P.G.) College, Dehradun, Uttarakhand) : Role of magnetic carpet in coronal heating. J Astrophys Astr 2008, 29(1-2), 253-6.
One of the fundamental questions in solar physics is how the solar corona maintains its high temperature of several million Kelvin above photosphere with a temperature of 6000 K. Observations show that solar coronal heating problem is highly complex with many different facts. It is likely that different heating mechanisms are at work in the solar corona. The separate kinds of coronal loops may also be heated by different mechanisms. Using data from instruments onboard the Solar and Heliospheric Observatory (SOHO) and from the more recent Transition Region and Coronal Explorer (TRACE) scientists have identified small regions of mixed polarity, termed magnetic carpet contributing to solar activity on a short time scale. Magnetic loops of all sizes rise into the solar corona, arising from regions of opposite magnetic polarity in the photosphere. Energy released when oppositely directed magnetic fields meet in the corona is one likely cause for coronal heating. There is enough energy coming up from the loops of the "magnetic carpet" to heat the corona to its known temperature.
Tripathy S C;Wet S de;Jain K;Clark R;Hill F
018361 Tripathy S C;Wet S de;Jain K;Clark R;Hill F (National Solar Observatory, , Tucson, AZ 85719, USA, Email: firstname.lastname@example.org) : Helioseismic ring analysis of CME source regions. J Astrophys Astr 2008, 29(1-2), 207-10.
Apply the ring diagram technique to source regions of halo coronal mass ejections (CMEs) to study changes in acoustic mode parameters before, during, and after the onset of CMEs. Finds that CME regions associated with a low value of magnetic flux have line widths smaller than the quiet regions, implying a longer life-time for the oscillation modes. It is suggested that this criterion may be used to forecast the active regions which may trigger CMEs.
4 illus, 4 ref
Tripathy S C
018360 Tripathy S C (NO, , National Solar Observatory, 950 N. Cherry Avenue, Tucson, AZ 85719, USA, Email: email@example.com) : Seismic signatures of solar flares. Asian J Phys 2008, 17(3-4), 533-53.
The detection of helioseismic signature of flares has opened up new possibilities for comprehending the seismic activity of the Sun and flare dynamics. Review focus on the current state of knowledge relating solar flares to oscillations of the Sun.
11 illus, 1 table, 70 ref
Sylwester J;Kuzin S;Kotov Y D;Farnik F;Reale F
018359 Sylwester J;Kuzin S;Kotov Y D;Farnik F;Reale F (Space Research Center, Polish Academy of Sciences, Kopernika 11, 51-622 Wroclaw, Poland, Email: firstname.lastname@example.org) : SphinX: A fast solar Photometer in X-rays. J Astrophys Astr 2008, 29(1-2), 339-43.
The scientific goals and construction details of a new design, Polish X-ray spectrophotometer are given. It will be incorporated within the Russian TESIS X and EUV complex aboard the forthcoming CORONAS solar mission. SphinX (Solar Photometer in X-rays) will use PIN silicon detectors for high time resolution (0.01 s) measurements of the solar spectra of quiet and active corona in the range 0.5-15keV. A new filter-fluorescence target concept will be employed to allow for a fast photometry of the solar X-ray flux variations in selected, well defined narrow spectral bands including the Fe xxvi and Fe xxv iron line groups.
3 illus, 2 ref
Sylwester B;Sylwester J;Phillips K J H
018358 Sylwester B;Sylwester J;Phillips K J H (Space Research Center, Polish Academy of Sciences, Kopernika 11, 51-622, Email: email@example.com) : X-ray studies of flaring plasma. J Astrophys Astr 2008, 29(1-2), 147-50.
Presents some methods of X-ray data analysis employed in the laboratory for deducing the physical parameters of flaring plasma. Used a flare well observed with Polish instrument RESIK aboard Russian CORONAS-F satellite. Based on a careful instrument calibration, the absolute fluxes in a number of individual spectral lines have been obtained. The analysis of these lines allows us to follow the evolution of important thermodynamic parameters characterizing the emitting plasma throughout this flare evolution.
3 illus, 7 ref
018357 Strachan L (NO, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA, Email: firstname.lastname@example.org) : Ultraviolet spectroscopic observations of coronal streamers in the SOHO era. J Astrophys Astr 2008, 29(1-2), 167-70.
Measurements made with the Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory can be used to determine physical parameters in the solar corona such as hydrogen and ion kinetic temperatures, electron densities, and absolute elemental abundances. Hydrogen and ion outflow velocities can be determined by combining the UV spectroscopic measurements with white light polarized brightness measurements. These combined measurements can be used to reveal physical characteristics of coronal streamers. Authors have studied plasma properties, such as the variation of plasma outflows in quiescent streamers, primarily in classic helmet streamers at solar minimum. Outflows have not been observed in the centers of coronal streamers suggesting that these are closed magnetic field regions. We propose to study all of the coronal streamers in the UVCS synoptic dataset in order to investigate different types of streamers and their long-term evolution.
1 illus, 8 ref
Stenflo J O
018356 Stenflo J O (NO, Institute of Astronomy, ETH Zurich, CH-8092 Zurich, Switzerland) : Solar magnetic fields. J Astrophys Astr 2008, 29(1-2), 19-28.
Since the structuring and variability of the Sun and other stars are governed by magnetic fields, much of present-day stellar physics centers around the measurement and understanding of the magnetic fields and their interactions. The Sun, being a prototypical star, plays a unique role in astrophysics, since its proximity allows the fundamental processes to be explored in detail. The PRL anniversary gives us an opportunity to look back at past milestones and try to identify the main unsolved issues that will be addressed in the future.
5 illus, 24 ref
Stalin C S;Hegde M;Sahu D K;Parihar P S; Anupama G C;Bhatt B C;Prabhu T P
018355 Stalin C S;Hegde M;Sahu D K;Parihar P S; Anupama G C;Bhatt B C;Prabhu T P (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: email@example.com) : Night sky at the Indian astronomical observatory during 2000-2008. Bull Astr Soc India 2008, 36(2-3), 111-27.
Presents an analysis of the optical night sky brightness and extinction coefficient measurements in UBVRI at the Indian Astronomical Observatory (IAO), Hanle, during the period 2000-2008. They are obtained from an analysis of CCD images acquired at the 2 m Himalayan Chandra Telescope (HCT) at IAO. Night sky brightness was estimated using 210 HFOSC images obtained on 47 nights and covering the declining phase of solar activity cycle-23. The zenith corrected values of the moonless night sky brightness in mag arcsec-2 are 22.14 ± 0.32 (U), 22.42 ± 0.30 (B), 21.28 ± 0.20 (V), 20.54 ± 0.37 (R) and 18.86 ± 0.35 (I) band. This shows that IAO is a dark site for optical observations. No clear dependency of sky brightness with solar activity (implied by the 10.7 cm solar flux) is found. Extinction values at IAO are derived from an analysis of 1325 images over 58 nights. They are found to be 0.36 ± 0.07 in U-band, 0.21 ± 0.04 in S-band, 0.12 ± 0.04 in F-band, 0.09 ± 0.04 in R-band and 0.05 ± 0.03 in I-band. On an average, extinction during the summer months is slightly larger than that during the winter months. This might be due to an increase of dust in the atmosphere during the summer months. No clear evidence for a correlation between extinction in all bands and the average night time wind speed is found. Also, presented here, is the low resolution moonless optical night sky spectrum for IAO covering the wavelength range 3000 - 9300 A. Features from O, OH,"N and Na are seen in the spectra. Hanle, thus has the required characteristics of a good astronomical site in terms of night sky brightness and extinction, and could be a natural candidate site for any future large aperture Indian optical-infrared telescope(s).
7 illus, 8 tables, 30 ref