011035   Darshan Singh;Manjit Singh (Phys Dep, Punjabi Univ, Patiala-147 002, Email: dsjphy@yahoo.com) : Effect of western disturbances on LF 164 kHz propagation. Indian J Radio Space Phys 2005, 34(5), 328-31.

Western disturbances affect the mesosphere/lower thermosphere such that low frequency propagation field strength exhibits fadings/scintillations. The degree of effect depends upon the severity of disturbance. Periodic variations are due to internal atmospheric gravity waves and scintillations are due to irregularities produced by thundercloud activity. The study represents magnitude of electrostatic coupling between the troposphere and ionosphere.

2 illus, 2 tables, 12 ref

011034   Chakrabarti S K;Saha M;Khan R;Mandal S; Acharyya K;Saha R (NO, Cent for Space Phys, 43 Chalantika, Garia Station Road, Kolkata-700 084) : Possible detection of ionospheric disturbances during the Sumatra-Andaman islands earthquakes of December, 2004. Indian J Radio Space Phys 2005, 34(5), 314-18.

Results of the continuous monitoring of ionospheric disturbances using very low frequency (VLF) radio waves during the recent Sumatran earthquake are presented. Strong and anomalous shifts in the sunset-terminator are found during 22-31 Dec. 2004. Anomalous behaviours in daytime observation are also detected. On 26 Dec. 2004, there were altogether 23 major earthquakes and aftershocks (magnitudes 5.0-9.0 on Richter scale). There were 10 such earthquakes on 27 Dec., 2 on 28 Dec., 7 on 29 Dec. and 4 on the 30 Dec. 2004. Given that there was no major earthquake on 22 December, though anomaly began on that day, it is believed that VLF monitoring could be a useful tool for earthquake predictions as well.

4 ilus, 12 ref

010018   Tripathi L;Shrivastava A K;Tiwari A K;Khare A;Singh A (Phys Dep, Government T.R.S. Coll, Rewa-486 001) : Interplanetary parameters in relation to solar activity. Ultra Scient phys Sci 2005, 17(1), 5-8.

Solar wind streams are continuously blowing through solar corona into interplanetary space and are effected by different solar and interplanetary parameters, Investigates the correlative nature of different interplanetary parameters, while dividing the complete solar cycle in four categories taken solar cycle 22.

8 illus, 1 table, 8 ref

010017   Mishra V D;Mathur P;Singh R P (NO, Snow and Avalanche Study Establ (SASE), Chandigarh (UT)-160 036, Email: vd_mishra@rediffmail.com) : Qualitative and quantitative analysis of snow parameters using passive microwave remote sensing. J Indian Soc Remote Sens 2005, 33(3), 381-93.

Snow cover is an important variable for climatic and hydrologic models due to its effect on surface albedo, energy, and mass balance. Satellite observations successfully provde a global and comprehensive hemispheric-scale record of the short-term, as well as inter-seasonal variations in snow cover. Passive microwave sensors provide an excellent method to monitor temporal and spatial variations in large-scale snow cover parameters, overcoming problems of cloud cover. Using microwave remote sensing data, snow parameters (snow surface temperature, snow water equivalence, scattering index, emissivity, snow depth) have been retrieved to integrate with the snow cover simulation model developed by SASE for avalanche risk assessment on regional basis. Multispectral and multitemporal brightness temperature data obtained from the Special Sensor Microwave Imager (SSM/I), flown onboard the DMSP satellites, for the period November 2000 to April 2001 and from November 2001 to February 2002 have been analysed. A comparatiave data set on snow measurements and meteorological observations of a region covering large area of Pir-Panjal and the Greater Himalayan range, available on near real time basis from SASE field observations were also used. Model calculations were carried out to study the effects of atmospheric transmission on the microwave radiation emitted from the snow covered and snow free ground and atmosphere.

12 illus, 12 ref

010016   Kulinder Pal Singh (Astr and Astrophys Dep, Tata Inst of Fundamental Res, Homi Bhabha Road, Mumbai-400 005, Email: singh@tifr.res.in) : Techniques in X-ray astronomy 2. Imaging Detectors. Resonance 2005, 10(7), 8-20.

Excellent X-ray images produced by X-ray telescopes require the use of detectors with imaging capability at the focal plane of the telescopes. Author has described many X-ray detectors that have been used over the years. These can broadly be classified into two physical types: non-dispersive and dispersive. Traditionally the simple non-dispersive types have been used extensively in X-ray astronomy. The advancement of solid state technologies, cryogenics, and the quality of X-ray imaging has led to many new detectors of both types. Both the traditional and the new types of detectors are described briefly here with emphasis on principles and some technical details.

8 illus

010015   Kiran Chand T R;Madhavi Latha K;Badarinath K V S;Murthy M S R (For and Ecology Div, Natn Remote Sens Ag (Department of Space Government of India), Balanagar, Hyderabad-500 037, Email: badrinath_kvs@nrsa.gov.in) : Analysis of terra modis satellite data for ecological impact assessment (EcIA) studies. J Indian Soc Remote Sens 2005, 33(3), 457-63.

4 illus, 1 table, 10 ref

010014   Joshi P K;Rawat G S;Padaliya H;Roy P S (NO, Indian Inst of Remote Sens (NRSA), Dehra Dun-248 001, Email: joshi@iirs.gov.in) : Land use/land cover identification in an alpine and arid region (Nubra valley, Ladakh) using satellite remote sensing. J Indian Soc Remote Sens 2005, 33(3), 371-80.

The remote sensing technology has been widely used for mapping the vegetation types in the tropical landscapes. However, in the temperature and alpine arid regions of India very few studies have been conducted using this technique. In the mountainous temperature arid conditions the vegetation is largely confined to marsh meadows, streams courses, river valleys and moist pockets close to snowfields. The ground truth collection in these zones are physically challenging due to tough terrain and restricted mobility. The detailed mapping of vegetation and other land use classes in these areas is therefore, extremely difficult. It describes the use of IRS-ID LISS III sensor for deciphering land cover details Nubra Valley, northern protion of Ladakh Autonomous Hill Council, Jammu & Kashmir (India). This analysis essentially emphasizes in bringing out various vegetation classes (specially Hippophae rhamnoides and other medicinal plant communities) along the narrow river valleys.

4 illus, 2 tables, 15 ref

010013   Chauhan H B;Nayak S (NO, Space Applics Cent, Ahmedabad-380 015, Email: harshad@sac.isro.org) : Land use/land cover changes in near Hazira region, Gujarat using remote satellite data. J Indian Soc Remote Sens 2005, 33(3), 413-20.

Human activities have great influence on fragile coastal ecosystem. For sustainable use of coastal resources it is very important to understand land use/land cover changes and its implications on coastal systems. Remote sensing data because of its synoptic, multispectral and multi temporaal nature can be very good soruce for mapping, monitoring and understanding these changes. IRS LISS III sensor data were used to find out the rate of land use/land cover changes in Hazira area near Surat, Gujarat. Because of major industrial activities it has become a hot spot area which requires regular monitoring. In the study, land cover information of the period 1970-1972 from the Survey of India topographical maps, and satellite data of the year 1989 and 1999-2002 have been used and visual analysis has been carried out to measure the land use/land cover changes. Erosion and deposition has been observed around the newly constructed jetty. Forest area and agriculture area is found to decrease, whereas built-up area has increased.

3 illus, 1 table, 25 ref

008786   Singh G P;Kotambkar S (Dep of Math, Visvesvaraya Natn Inst or Technol (formerly V. Regional Coll of Engin, Nagpur 440 011, Email: gpsingh@vnitnagpur.ac.in) : Charged fluid distribution in higher dimensional spheroidal space-time. Pramana J Phys 2005, 65(1), 35-41.

General solution of Einstein field equations corresponding to a charged fluid distribution on the background of higher dimensional spheroidal space-time is obtained. The solution generates several known solutions for superdense star having spheroidal space time geometry.

25 ref

008785   Gurjar S B;Padmanabhan N (Space Applics Cent, Indian Space Res Organisation, Ahmedabad-380 015) : Study of various resampling techniques for high-resolution remote sensing imagery. J Indian Soc Remote Sens 2005, 33(1), 112-20.

Resampling is the technique of manipulating a digital image and transforming it into another form. This manipulation could be for various reasons - change of resolution, change of orientation, i.e. rotation, change of sampling points, etc. This technique is used extensively in image processing for all applications, including medical, industrial and of course in remote sensing. This is because the image as it is captured will have limitations imposed by the imaging geometry or camera. However, for analysis, will be performed to have the image in a different and better form. By this technique, author are trying to achieve what is not able to achieve by the imaging process. Thus, if author considers remote sensing data, the data acquired will have the constraints imposed by the satellite orbit, payload, etc. However, for applications, the input resolution might not be sufficient. Besides, the image will be acquired in a way consistent with the orbit. Thus in the case of sun synchronous orbits, the images are always inclined to true North. Besides, the images will have inherent distortions due to the peculiar characteristics of the payload and the relative geometry with the earth. However, for extraction of correct information from these images, these distortions have to be removed. Besides. comparing these images with maps, the sampling intervals have to be made uniform, and the data put in proper map projections. All these call for resampling of the input image. So far, author have been using either the cubic convolution or nearest neighbor method in all the data products generated from the IRS (Indian Remote Sensing) series of satellites. These two methods were sufficient for the data we have been getting till now. However, with the impending launch of TES (Technology Experiment Satellite) and IRS P6, we are entering an era of obtaining very high-resolution data. Manipulating such data needs improved resampling algorithms. To this end the surveys the existing methods of resampling and describes some experiments that were carried out to evaluate the various methods, and finally concludes on the method to be adopted for the IRS program under consideration.

4 illus, 1 table, 3 ref

007716   Turcotte S (NO, Bishop's University, Lennoxville, Canada, JIM IZ7, Email: turcotte@apollo.ubishops.ca) : Using the seismology of non-magnetic chemically peculiar stars as a probe of dynamical processes in stellar interiors. J Astrophys Astr 2005, 26(2-3), 231-9.

Chemical composition is a good tracer of the hydrodynamical processes that occur in stars as they often lead to mixing and particle transport. By comparing abundances predicted by models and those observed in stars one can infer some constraints on those mixing processes. As pulsations in the stars are often very sensitive to chemical composition, one can use asteroseismology to probe the internal chemical composition of stars where no direct observations are possible. Focusses on main sequence stars Am, λ Bootis, and HgMn stars and discuss what we can learn of mixing processes in these stars from seismology.

6 illus, 10 ref

007715   Simon Jeffery C (Aramgarh Obs, College Hill, Armagarh BT61 9DG, Northern Ireland) : Pulsations in Subdwarf B Star. J Astrophys Astr 2005, 26(2-3), 261-71.

Subdwarf B stars play a significant role in close binary evolution and in the hot star content of old stellar populations, in particular in giant elliptical galaxies. While the question of their origin poses several problems for stellar evolution theory, one of their most fascinating properties is the presence of multi-periodic 2-3 minute oscillations. Interpreting these oscillations optimally requires the correct identification of the modes. Partial identifications can be obtained using high-speed observations of radial velocity and colour variations Reviews some of the several attempts to make such observations, most recently with the Multi-Site Spectroscopic Telescope campaign and with ULTRACAM.

6 illus, 48 ref

007714   Shibahashi H (Dep Astr, University of Tokyo, Tokyo 113 0033, Japan, Email: shibahashi@astron.s.u-tokyo.ac.jp) : Theory of Asteroseismology. J Astrophys Astr 2005, 26(2-3), 139-60.

The increasing number of pulsating modes in a star leads to the increase of the amount of information derived from the pulsation. Probing the invisible interior of stars is a dream come true. Summarizes the fundamental properties of stellar pulsations and the excitation mechanisms, emphasizing several cases of recent progress.

45 ref

007713   Seetha S;Ashoka B N;Marar T M K (Space Astr Instrumentation Div, ISRO Satellite Centre, Airport Road, Bangalore 560 017, Email: seetha@isac.ernet.in) : Results from the whole earth telescope - indian contributions. J Astrophys Astr 2005, 26(2-3), 301-9.

5 illus, 32 ref

007712   Satosh Joshi (NO, Aryabhatta Research, Institute of Observational Sciences (ARIES), Manora Peak, Nainital 263 129, Email: santosh@aries.ernet.in) : The Nainital-cape survey: a search for variability in AP and Am stars. J Astrophys Astr 2005, 26(2-3), 193-201.

The "Nainital-Cape Survey" program for searching photometric variability in chemically peculiar (CP) stars was initiated in 1997 at ARIES, Nainital. The Am stars HD 98851, HD 102480, HD 13079 and HD 113878 were discovered to exhibit 8 Scuti type variability. Photometric variability was also discovered in HD 13038, for which the type of peculiarity and variability is not fully explained. The null results of this survey are also presented and discussed.

6 illus, 22 ref

007711   Samadi R;Goupil M J;Alecian E;Baudin F; Georgobiani D;Trampedach R;Stein R;Nordlund A (Observatoire de Paris, , 5 place J. Janssen, 92195 Meudon, France) : Excitation of solar-like oscillations: from PMS to MS stellar models. J Astrophys Astr 2005, 26(2-3), 171-84.

The amplitude of solar-like oscillations results from a balance between excitation and damping. As in the sun, the excitation is attributed to turbulent motions that stochastically excite the p modes in the uppermost part of the convective zone. Presented a model for the excitation mechanism. Comparisons between modeled amplitudes and helio and stellar seismic constraints are presented and the discrepancies discussed. Finally the possibility and the interest of detecting such stochastically excited modes in pre-main sequence stars are also discussed.

3 illus, 40 ref

007710   Sagar R;Mary D L (NO, Aryabhatta Research Institute of Observational Sciences, (ARIES), Manora Peak, Nainital 263 129, Email: sagar@aries.ernet.in) : Facilities at ARIES for the Nainital-Cape Survey. J Astrophys Astr 2005, 26(2-3), 339-47.

A collaborative programme searching for mmag pulsations in chemically peculiar stars in the northern hemisphere was initiated in 1997 between Nainital, India, and Cape Town, South Africa. It was therefore named as the Nainital-Cape Survey programme. The detection limits imposed by the observing conditions (including atmospheric noise and telescope size) at both Manora Peak and Devasthal sites are described. The scintillation noise on the best photometric nights is ≈ 0.1 to 0.2 mmag for these sites. Both places allow one to detect few mmag variation in bright stars (B ≤ 12 mag), and are therefore particularly well-suited for carrying out the proposed survey work. The main characteristics of the three-channel photometer developed at ARIES for carrying out the observations are also presented. This excellent instrument has been used extensively since 1999 at the f/13 Cassegrain focus of ARIES' 104cm telescope. In particular, it allowed the survey to result in the discovery of δ Scuti like pulsations in four Am stars, in one rapidly oscillating Ap star, and in a number of probable variables so far. The future prospects are then presented, which regard the acquisition of a high speed time series CCD photometer, a project to build a 3-metre class telescope at Devasthal, and collaborative observations with Indian and foreign astronomical sites.

4 illus, 25 ref

007709   Rao N K;Sriram S;Jayakumar K; (NO, Indian Institute of Astrophysics, Bangalore-560 034) : High resolution stellar spectroscopy with VBT echelle spectrometer. J Astrophys Astr 2005, 26(2-3), 331-8.

The optical design and performance of the recently commissioned fiber fed echelle spectrometer of 2.34 meter Vainu Bappu Telescope are described. The use of it for stellar spectroscopic studies is discussed.

6 illus, 8 ref

007708   Mukadam A S;Nather R E (Dep Astr, University of Washington, Seattle, WA 98195 1580, U.S.A., Email: anjum@astro.washington.edu) : Argos: an optimized time-series photometer. J Astrophys Astr 2005, 26(2-3), 321-30.

Designes a prime focus CCD photometer, Argos, optimized for high speed time-series measurements of blue variables for the 2.1 m telescope at McDonald Observatory. Lack of any intervening optics between the primary mirror and the CCD makes the instrument highly efficient. Measured an improvement in sensitivity by a factor of nine over the 3-channel PMT photometers used on the same telescope and for the same exposure time. The CCD frame transfer oper ation triggered by GPS synchronized pulses serves as an electronic shutter for the photometer. This minimizes the dead time between exposures, but more importantly, allows a precise control of the start and duration of the exposure. Expected the uncertainty in our timing to be less than 100 μs.

3 illus, 1 table, 39 ref

007707   Mkrtichian D E;Hatzes A P (ARCSE Sejong Univ Seoul 143 747 Korea Astr Obs, Odessa National University, Shevchenko Park, Odessa 65014, Ukraine, Email: david@arcsec.sejong.ac.kr) : HD 101065 the most peculiar star; first results from precise radial velocity study. J Astrophys Astr 2005, 26(2-3), 185-91.

Discusses the prospects for asteroseismology with spatial resolution and motivate studtes of the most chemically peculiar roAp star HD 101065. Presents the first results from a high-precision radial velocity (RV) study of HD 101065 based on data spanning four nights that were acquired using the HARPS echelle-spectrometer at the ESO 3.6 m telescope. The analysis of individual nights showed the amplitude and phase modulation of the dominant mode. The analysis of the whole data set showed the presence of multi-periodic oscillations with two groups of equally-spaced modes. Finds Δν = 65.2 μ and δν= 7.3μ for the large and the small spacing, respectively. HD 101065 is the only roAp star to show the existence of two groups of l = 0, 2 and l = 1, 3 excited modes.

4 illus, 21 ref

007706   Metcalfe T S (High Altitude Obs, NCAR, P.O. Box 3000, Boulder CO 80307, USA, Email: travis@hao.ucar.edu) : Lessons for Asteroseismology from White Dwarf Stars. J Astrophys Astr 2005, 26(2-3), 273-81.

The interpretation of pulsation data for sun-like stars is currently facing challenges quite similar to those faced by white dwarf modelers ten years ago. The observational requirements for uninterrupted long-term monitoring are beginning to be satisfied by successful multi-site campaigns and dedicated satellite missions. But exploration of the most important physical parameters in theoretical models has been fairly limited, making it difficult to establish a detailed best-fit model for a particular set of oscillation frequencies. Reviews the past development and the current state of white dwarf asteroseismology, with an emphasis on what this can tell us about the road to success for asteroseismology of other types of stars.

4 illus, 31 ref

007705   Mary D L (NO, Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital 263 129, Email: dmary@upso.ernet.in) : On the Analysis of Light Curves in Asteroseismology. J Astrophys Astr 2005, 26(2-3), 283-92.

Provides a detailed introduction to the main problems arising when analyzing light curves in asteroseismology. Attention is first paid to the signal model delivered by the pulsating stars and to the noise sources corrupting this model in photometric observations. The main pitfalls and ambiguities occurring in Fourier analysis are summarized and illustrated. Some classical, Least Squares (LS) based methods for spectrum analysis are analyzed and commented on from the point of view of ill-posed problems. The insight that can be gained from such analyses is discussed.

3 illus, 36 ref

007704   Kurtz D W (Cent Astrophys Univ Cent Lancashire, , Preston PR1 2HE, UK, Email: dwkurtz@uclan.ac.uk) : Asteroseismology: Past, Present and Future. J Astrophys Astr 2005, 26(2-3), 123-38.

Asteroseismology studies stars with a wide variety of interior and surface conditions. For two decades asteroseismic techniques have been applied to many pulsating stars across the HR diagram. Asteroseismology is now a booming field of research with stunning new discoveries; I highlight a personal selection of these in this review, many of which are discussed in more detail elsewhere in these proceedings. For many years the Nainital-Cape Survey for northern roAp stars has been running at ARIES, so I emphasise new spectroscopic results for roAp stars and point out the outstanding prospects for the planned ARIES 3-m telescope at Devastal. High precision spectroscopy has revolutionised the asteroseismic study of some types of stars - particularly solar-like oscillators and roAp stars - while photometry is still the best way to study the frequency spectra that are the basic data of asteroseismology. New telescopes, new photometers and space missions are revolutionising asteroseismic photometry. In addition to the ground-based potential of asteroseismic spectroscopy, India has the knowledge and capability for space-based asteroseismic photometry. The future for asteroseismology is bright indeed, especially for Indian astronomers.

7 illus, 39 ref

007703   Hojaev A S (Ulugh Beg Astr Inst, Center for Space Research, Uzbek Academy of Sciences, Tashkent, Uzbekistan, Email: ash@astrin.uzsci.net) : Upgradation of MOT and its relevance to WET campaigns. J Astrophys Astr 2005, 26(2-3), 311-19.

The Maidanak One-meter Telescope (MOT) is a Ritchey-Chretien telescope by Carl Zeiss, located atop Maidanak in Uzbekistan, where site parameters indicate excellent atmospheric seeing conditions. An effort to computerize the MOT, jointly made by an Uzbek, Taiwanese and Baltic consortium, is expected to complete in 2005. Monitoring the variability of star clusters will be among the first scientific projects to be carried out. Equipped with sensitive CCD cameras, the MOT, with its middle-Asia geographic location, will be a desirable addition to the Whole Earth Telescope (WET) network. Describes the upgrade engineering and instrumentation of the telescope and how the system can be used in future campaigns.

6 illus, 3 tables, 14 ref

007702   Hojaev A S (Ulugh Beg Astr Inst, Center for Space Research, Uzbek Academy of Sciences, Tashkent, Uzbekistan, Email: ash@astrin.uzsci.net) : Collaborative research of open star clusters. J Astrophys Astr 2005, 26(2-3), 293-9.

Preliminary results on observations of open clusters are presented. The project has been initiated in the framework of the Uzbek-Taiwan and Taiwan-Baltic collaboration, mainly to upgrade and make use of facilities at Maidanak Observatory. Presents detailed, multi-wavelength studies of the young cluster NGC 6823 and the associated complex nebulosity, to diagnose the young stellar population and star formation history in the region. In addition, 7 compact open clusters have been monitored for stellar variability. Showes now observations like these could feasibly be used to look for exoplanet transit events, Also expectes to join the Whole-Earth Telescope effort in future campaigns for asteroseismology.

3 illus, 3tables, 39 ref

007701   Handler G (Institut fur Astronomie, Universitat Wien, Turkenschanzstrasse 17, A 1180 Wien, Austria, Email: handler@astro.univie.ac.at) : Asteroseismology of δ Scuti and γ Dorados Stars. J Astrophys Astr 2005, 26(2-3), 240-7.

Gives an overview of past and present efforts to make seismology of δ Scuti and γ Doradus stars possible. Previous work has not led to the observational detection and identification of a sufficient number of pulsation modes for these pulsators for the construction of unique seismic models. However, recent efforts including large ground-based observational campaigns, work on pre-main sequence pulsators, asteroseismic satellite missions, theoretical advances on mode identification methods, and the discovery of a star showing simultaneous self-excited δ Scuti and γ Doradus oscillations suggest that are may be able to explore the interiors of these pulsators in the very near future.

4 illus, 23 ref

007700   Goupil M J;Dupret M A;Samadi R;Boehm R;Boehm T;Alecian E;Suarez J C;Lebreton Y;Catala C (LESIA UMR 8109, , Observatoire de Paris, 5 place J. Janssen, 92195 Meudon, France) : Asteroseismology of δ Scuti Stars: Problems and Prospects. J Astrophys Astr 2005, 26(2-3), 249-59.

Briefly outlines the state-of-the-art seismology of δ Scuti stars from a theoretical point of view: why is it so difficult a task? The recent theoretical advances in the field that these difficulties have influenced are also discussed.

2 illus, 46 ref

007699   Girish V (NO, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, Email: giri@tifr.res.in) : HD 12098 and other results from Nainital-cape survey. J Astrophys Astr 2005, 26(2-3), 203-11.

Nainital-Cape Survey was started with an aim to search for new rapidly oscillating Ap stars in the northern hemisphere. Discovered one new mono-periodic roAp star HD 12098. The frequency separation of HD 12098 suggests a rotation period of 5.5 days for the star. Summarized the observations of HD 12098 and briefly discussed the results of the multi-site observation campaign organized to resolve the ambiguity in the determination of the rotation period of HD 12098. Other interesting results like non-oscillating Ap stars discovered and two candidate stars in which roAp periodicity is seen but not confirmed are also discussed.

10 illus, 11 ref

007698   Fossat E (Laboratoire Universitaire d'Astrophysique de Nice, Universite de Nice, France, Email: Eric.Fossat@unice.fr) : The concordia station on the antarctic plateau: the best site on earth for the 21st century astronomers. J Astrophys Astr 2005, 26(2-3), 349-57.

On the Antarctic plateau, a joint project of French and Italian polar programmes is nearing completion: the Concordia station will be open for winter-over operation in 2005. The high altitude and high latitude of this site, the exceptionally cold, clear and stable atmosphere, its incredible astronomical seeing, the almost indefinitely flat snow surface and the not-so-difficult access make this site the most promising on Earth for future ground-based astronomical projects in various fields, including long term photometry, infrared high sensitivity imaging and high angular resolution and high contrast imaging.

5 illus, 7 ref

007697   Dorokhova T;Dorokhov N (Astr Obs, Odessa National University, Ukraine, Email: tnd@te.net.ua) : The Dushak-erekdag survey of roAp stars. J Astrophys Astr 2005, 26(2-3), 223-9.

The search of roAp stars at Mt. Dushak-Erekdag Observatory was started in 1992 using the 0.8 m Odessa telescope equipped with a two-star high-speed photometer. Observed more than a dozen stars so far and discovered HD 99563 as roAp star while BD + 8087 is suspected to have rapid oscillations. Negative results of observations for the search of rapid oscillations in four stars in NGC 752 are also discussed.

4 illus, 2 tables, 33 ref

007696   Cunha M S (Centro de Astrofisica da, Universidade do Porto, Rua das estrelas, 4150, Porto, Portugal, Email: mmcunha@astro.up.pt) : Asteroseismic theory of rapidly oscillating Ap stars. J Astrophys Astr 2005, 26(2-3), 213-21.

Reviews some of the important advances made over the last decade concerning theory of roAp stars.

5 illus, 17 ref

007695   Anita H M (NO, Tata lnstitute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, Email: antia@tifr.res.in) : Helioseismology. J Astrophys Astr 2005, 26(2-3), 161-9.

The sun being the nearest star, seismic observations with high spatial resolution are possible, thus providing accurate measurement of frequencies of about half million modes of solar oscillations covering a wide range of degree. With these data helioseismology has enabled us to study the solar interior in sufficient detail to infer the large-scale structure and rotation of the solar interior. With the availability of high quality helioseismic data over a good fraction of a solar cycle it is also possible to study temporal variations in solar structure and dynamics. Some of these problems and recent results are discussed.

4 illus, 49 ref

006604   Tikekar R;Thomas V O (Dep Math, Sardar Patel Univ, Vallabh, Vidyanagar-388 120) : A relativistic core-envelope model on pseudospheroidal space-time. Pramana J Phys 2005, 64(1), 5-15.

Core-envelope model for superdense matter distribution with the feature - core consisting of anisotropic fluid distribution and envelope with isotropic fluid dis tribution is reported on the background of pseudospheroidal space-time. The physical plausibility of the model is examined analytically and numerically.

2 illus, 12 ref

006603   Parry A O;Romero-Enrique J M (Dep Math, Imperial Coll, 180 Queen's Gate, London SW7 2BZ, UK) : Phase transitions, interfacial fluctuations and hidden symmetries for fluids near structured walls. Pramana J Phys 2005, 64(5), 709-25.

Fluids adsorbed at micro-patterned and geometrically structured substrates can exhibit novel phase transitions and interfacial fluctuation effects distinct from those characteristic of wetting at planar, homogeneous walls. Author review recent theoretical progress in this area paying particular attention to filling transitions pertinent to fluid adsorption near wedges, which have highlighted a deep connection between geometrical and contact angles. It show that filling transitions are not only characterized by large scale interfacial fluctuations leading to universal critical singularities but also reveal hidden symmetries with short-ranged critical wetting transitions and properties of dimensional reduction. Author propose a non-local interfacial model which fulfills all these properties and throws light on long-standing problems regarding theorder of the 3D short-range critical wetting transition.

4 illus, 33 ref

006602   Ajai (For Ld use Photogrammetry, Grp Space Applics Cent (ISRO), Ahmedabad- 380015) : Mapping from high resolution satellite images and global positioning systems. Natn Acad Sci Lett 2004, 27(9-10), 329-38.

Development in space based imaging and the sophisticated image processing techniques, during the past three decades, have revolutionized the field of cartography and mapping. Paper describes the recent advances in the Satellite Remote Sensing, Global Positioning System and GIS as well as their uses in the process of mapping. Studies on preparation of thematic as well as cartographic quality base maps using satellite images and GPS have been described.

6 illus, 2 tables, 6 ref

005472   Omar A;Dwarakanath K S (Raman Res Inst, , Sadashivanagar, Bangarlore-560 080, Email: aomar@upso.ernet.in) : Radio continuum and far-infrared emission from the galaxies in the eridanus group. J Astrophys Astr 2005, 26(1), 89-102.

The Eridanus galaxies follow the well-known radio-FIR correlation. The majority (70%) of these galaxies have their star formation rates below that of the Milky Way. The galaxies that have a significant excess of radio emission are identified as low luminosity AGNs based on their radio morphologies obtained from the GMRT observations. There are no powerful AGNs (L_20cm <62> 10²³ W Hz^-1) in the group. The two most far-infrared and radio luminous galaxies in the group have optical and Hi morphologies suggestive of recent tidal interactions. The Eridanus group also has two far-infrared luminous but radio-deficient galaxies. It is believed that these galaxies are observed within a few Myr of the onset of an intense star formation episode after being quiescent for at least a 100 Myr. The upper end of the radio luminosity distribution of the Eridanus galaxies (L₂₀ cm <126> 1022 W Hz^-1) is consistent with that of the field galaxies, other groups, and late-type galaxies in nearby clusters.

6 illus, 3 tables, 26 ref

005471   Omar A;Dwarakanath K S (Raman Res Inst, , Sadashivanagar, Bangalore-560 080, Email: aomar@upso.ernet.in) : The H₁ content of the eridanus group of galaxies. J Astrophys Astr 2005, 26(1), 71-87.

The Hi content of galaxies in the Eridanus group is studied using the GMRT observations and the HIPASS data. A significant Hi deficiency up to a factor of 2-3 is observed in galaxies in the high galaxy density regions. The Hi deficiency in galaxies is observed to be directly correlated to the local projected galaxy density, and inversely correlated to the line-of-sight radial velocity. Furthermore, galaxies with larger optical diameters are predominantly in the lower galaxy density regions. It is suggested that the Hi deficiency in Eridanus is due to tidal interactions. In some galaxies, evidences of tidal interactions are seen. An important implication is that significant evolution of galaxies can take place in the group environment. In the hierarchical way of formation of clusters via mergers of groups, a fraction of the observed Hi deficiency in clusters could have originated in groups. The co-existence of S0s and severely Hi deficient galaxies in the Eridanus group suggests that tidal interaction is likely to be an effective mechanism for transforming spirals to S0s.

7 illus, 2 tables, 35 ref

005470   Omar A;Dwarakanath K S (Raman Res Inst, , Sadashivanagar, Bangalore-560 080, Email: aomar@upso.ernet.in) : GMRT H₁ observations of the Eridanus group of galaxies. J Astrophys Astr 2005, 26(1), 1-70.

The GMRT Hi 21 cm-line observations of galaxies in the Eri-danus group are presented. The Eridanus group, at a distance of <126> 23 Mpc, is a loose group of <126>200 galaxies. The group extends to more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is <126>240 km s^-1. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E + SO) and 70% (Sp + Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for <126> 200 h. Hi emission was detected from 31 galaxies. The channel rms of <126> 1 mJy beam^-1 was achieved for most of the image-cubes made with 4 h of data. The corresponding Ht column density sensitivity (3σ) is <126> 1 x 10²⁰ cm^-2 for a velocity-width of <126> 13.4 km s^-1. The 3σ detection limit of Hi mass is <126> 1.2 x 10⁷ M for a line-width of 50 km s^-1. Total Hi images, Hi velocity fields, global Hi line profiles, Hi mass surface densities, Hi disk parameters and Hi rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. These data will be used to study the Hi and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and Hi lopsidedness in galaxies.

16 illus, 5 tables, 54 ref

005469   Gomez Pulido J A;Vega Rodriguez M A;Sanchez Perez J M (NO, , ) : Parametric identification of solar series based on an adaptive parallel methodology. J Astrophys Astr 2005, 26(1), 103-15.

Persents an adaptive parallel methodology to optimize the identification of time series through parametric models, applying it to the case of sunspot series. Employ high precision computation of system identification algorithms, and use recursive least squares processing and ARMAX (Autoregressive Moving Average Extensive) parametric modelling. This methodology could be very useful when the high precision mathematical modelling of dynamic complex systems is required. After explaining the proposed heuristics and the tuning of its parameters, shows the results found for several solar series using different implementations.

9 illus, 3 tables, 11 ref

004382   Vijay V;Biradar R S;Inamdar A B;Baji S;Pikle M (NO, Central Institute of Fisheries Education (ICAR), Versova, Mumbai-400 061, Email: rbiradar@hotmail.com) : Mangrove mapping and change detection around Mumbai (Bombay) using remotely sensed data. Indian J Mar Sci 2005, 34(3), 310-15.

Remote sensing technology was used to detect changes in the mangrove habitat around the Mumbai suburban region. For this purpose, cloud free satellite images on the scale of 1 : 50,000 from Indian Remote Sensing (IRS) satellite IRS-ID and IRS-IC were used. The total area of mangroves in Mumbai suburban region has been estimated to be 56.40 km² (including mud flats) with dense mangroves contributing 45.4% to the total. During 1990 to 2001, a total mangrove area of 36.54 km² was lost, indicating a 39.32% decrease in the area of mangroves. It has been observed that the quantitative degradation of mangrove vegetation is largely due to burgeoning population pressure, construction and development activities, conversion to agricultural land and fish farms besides the effect of industrial effluents. Avicennia marina was found to be the most dominant mangrove species. Measures have been suggested for conservation and management of mangroves of Mumbai on a sustainable basis.

1 illus, 5 tables, 14 ref

004381   Subramanian K (Inter-University Centre for Astronomy and Astrophysics, , Post Bag 4, Ganeshkhind, Pune-411 007) : The physics of CMBR anisotropies. Curr Sci 2005, 88(7), 1068-87.

The observed structures in the universe are thought to have arisen from gravitational instability acting on small fluctuations generated in the early universe. These spatial fluctuations are imprinted on the cosmic microwave background radiation (CMBR) as angular anisotropics. The physics which connects initial fluctuations in the early universe to the observed anisotropies is fairly well understood, since for most part it involves linear perturbation theory. This makes CMBR anisotropies one of the cleanest probes of the initial fluctuations, various cosmological parameters governing their evolution and also the geometry of the universe. Atuhors review here in a fairly pedagogical manner the physics of the CMBR anisotropies and explain the role they play in probing cosmological parameters, especially in the light of the latest observations from the WMAP satellite.

2 illus, 70 ref

004380   Sheth J V;Sahni V (Inter University Centre for Astronomy and Astrophysics, , Post Bag 4, Ganeshkhind, Pune-411 007, Email: varun@iucaa.ernet.in) : Exploring the geometry, topology and morphology of large scale structure using minkowski functionals. Curr Sci 2005, 88(7), 1101-16.

Modern redshift surveys such as the 2 degree field Galaxy Redshift Survey (2dFGRS) and the Sloan Digital Sky Survey (SDSS) reveal fully 3-dimensional distribution of 10^5-6 galaxies over a large cosmological volume = 0.1 -1 [h^-1 Gpc]³. It is well established that the galaxies in these surveys show strong clustering. To the eye, the galaxies are distributed along sheet-like and/or filamentary superclusters. The CfA Great Wall, Southern Great Wall and the recently discovered SDSS Great Wall are the most popular superclusters of this kind. The superclusters are interwoven with one another, leaving ≥70% of volume devoid of any visible matter. This volume is occupied by voids. One is motivated to test the theoretical predictions for the clustering of galaxies against rich datasets resulting from these redshift surveys. To this end, several workers have recently proposed and developed an approach to quantify the large scale structure (LSS) by studying the geometry and topology of the superclusters and voids. Concretely, this can be achieved by evaluating the Minkowski functionals (MFs) for LSS-datasets. The MF-based approach further provides an unbiased description of the shapes and sizes of the elements of LSS, i.e. the superclusters and voids. This eventually leads to a framework within which to quantify LSS and compare outputs from simulations with redshift surveys. In the review authors give a summary of the progress made in this direction. After reviewing the status of observations and of numerical simulations, authors comment upon the nature of bias which itself serves as a link between theoretical predictions and observations. Next authors introduce MFs and give sufficient motivation, for employing them in cosmology. Authors summarize the methods developed for efficient numerical estimation of MFs for cosmological datasets. Authors stress the discriminatory power of MFs and of the derived morphological statistics, the Shape-finders. Shapefinders are specifically important to study the shapes and sizes of the superclusters and voids. Several successes of Shagefinders are highlighted here. further note some of the important effects of scale-dependent bias which are brought out by an MF-based study of the mock catalogues of galaxies. Such effects, Authors note, should be accounted for before comparing theoretical models with observations.

12 illus, 101 ref

004379   Sethi S K (Raman Research Institute, , Bangalore-560 080, Email: sethi@rri.res.in) : High redshift intergalactic medium: probes and physical models. Curr Sci 2005, 88(7), 1117-24.

Recent years have seen major advances in understanding the state of the intergalactic medium (IGM) at high redshift. Some aspects of this understanding are reviewed here. In particular, authors discuss: (1) Different probes of IGM like Gunn-Peterson test, CMBR anisotropies, and neutral hydrogen emission from reionization, and (2) some models of reionization of the universe.

8 illus, 44 ref

004378   Ranjan R;Singh R K;Sikka S K;Kakodkar A (Bhabha Atomic Research Centre, , Trombay, Mumbai-400 085, Email: rksingh@magnum.barc.ernet.in) : Cratering and spall simulation of Pokhran-1 event with three-dimensional transient finite element analysis. Curr Sci 2005, 88(7), 1132-41.

Three-dimensional transient numerical simulation of coupled gas cavity and geological medium problem resulting from underground nuclear explosion events is complex due to the gas cavity growth, resulting into the large deformations and large strains of the geological medium and shock-induced high strain-rate dependence of the response. However, it is important to establish the effects of local inelastic and nonlinear behaviour due to crushing and cracking of the geological medium, on the shock-waves near the source and the seismic signals beyond the elastic radius. The study also helps simulate the shock-wave reflection effects from the free surface near the ground zero, mound growth, spall near the free surface and the subsequent free fall of the mound due to gravity effect resulting in crater formation. The impacting spalled rock layers give rise to secondary seismic signals in addition to the primary signals that are observed in the near field which in turn are known to influence the far-field seismic signals. The article describes the capabilities of a three-dimensional transient finite element code, SHOCK-3D, for the short-time cavity growth, shock-wave propagation, mound growth and its free fall along with the settlement of the mound observed after a longer duration for the composite layer medium. The code predictions are benchmarked for the near-source experimental observations of the first Indian nuclear explosion event of 1974, carried out at the Pokhran test site.

8 illus, 19 ref

004377   Padmanabhan T (Inter-University Centre for Astronomy and Astrophysics, , Post Bag 4, Ganeshkhind, Pune-411 007, Email: nabhan@iucaa.ernet.in) : Dark energy: the cosmological challenge of the millennium. Curr Sci 2005, 88(7), 1057-67.

Recent cosmological observations suggest that nearly seventy per cent of the energy density in the universe is unclustered and has negative pressure. Several conceptual issues related to the modelling of this component ('dark energy'), which is driving an accelerated expansion of the universe, are reviewed with special emphasis on the cosmological constant as the possible choice for the dark energy.

3 illus, 45 ref

004376   Kuznetsov S N;Kudela K;Myagkova I N; Podorolsky A N;Ryumin S P;Yushkov B Y (Skobeltsyn Institute of Nuclear Physics, Moscow State University, Moscow, Russia) : First experience with SONG-M measurements of board CORONAS-F satellite. Indian J Radio Space Phys 2004, 33(6), 353-7.

One of the experiments on CORONAS-F satellite is SONG-M devoted to the study of hard electromagnetic and neutron emissions from the sun. Paper Presents the first results of the observation of γ-ray emission obtained by the instrument SONG-M during the period August 2001-May 2002.

2 illus, 1 table, 14 ref

004375   Kane R P (Instituto Nacional de Pesquisas Espaciais, INPE, C.P. 515, 12245-970, Sao Jose dos Campos, SP, Brazil, Email: kane@deg.inpe.br) : Variations of solar indices during the sunspot maximum years (1999-2002) of cycle 23. Indian J Radio Space Phys 2004, 33(6), 358-66.

Comparison of the evolutions of daily and monthly values of several solar indices during 1999-2002 indicated that the daily values had large day-to-day fluctuations with peak spacings differing considerably from the 27-day solar rotation period. Plots of the percentage increases (trough-to-peak) versus temperature of the source regions of the various indices indicated a double-humped structure. The monthly values showed many peaks. The average spacing was ~3.5 months (~100 days). The 12-month moving averages showed considerable differences. Some indices reached a maximum near March 2000. Some of these decreased since then and continue to decrease at present; but some reached a minimum near January 2001 and remained steady there, or started increasing again to reach a probable maximum near June 2002. Some indices did not have a maximum in March 2000 and continued to increase till June 2002. Thus, the evolutions of the various solar indices during the sunspot maximum of cycle 23 (1999-2002) are substantially different from each other. Obviously, the dynamical upheavals in the photosphere reach upper levels of the solar atmosphere with varying intensities.

5 illus, 2 tables, 23 ref

004374   Bagla J S (Harish-Chandra Research Institute, , Chhatnag Road, Jhunsi, Allahabad-211 019, Email: jasjeet@mri.ernet.in) : Cosmological N-body simulation: techniques scope and status. Curr Sci 2005, 88(7), 1088-1100.

Cosmological N-body simulations have become an essential tool for studying formation of large scale structure. These simulations are computationally challenging even though the available computing power gets better every year. A number of efficient algorithms have been developed to run large simulations with better dynamic range and resolution. Authors discuss key algorithms in the review, focusing on techniques used and their efficacy. N-body simulations solve a model that is an approximation of the physical model to be simulated, authors discuss limitations arising from this approximation and techniques employed for solving equations. Apart from simulating models of structure formation, N-body simulations have also been used to study aspects of gravitational clustering. Simulating formation of galaxies requires us to take many physical process into account; reviewed numerical implementations of key processed.

2 illus, 215 ref

003393   Venkataraman V;Anandarao B G (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: vvenkat@prl.ernet.in) : A near-infrared photometric study of the massive star forming region IRAS 21413+5442. Bull Astr Soc India 2005, 33(2), 141-4.

Authors report initial results from the near-infrared continuum studies on the massive star forming region IRAS 21413+5442. The colour-colour diagram and colour-magnitude diagram were used to determine the evolutionary stage and type of the central object powering the compact HII region. Distance to the object is estimated from H band flux in combination with published radio continuum fluxes.

2 illus, 17 ref

003392   Tej A;Lancon A;Scholz M (NO, Tata Institute of Fundamental Research, Mumbai-400 005) : Interpretation of angular diameter measurements of mira variables : Role of water. Bull Astr Soc India 2005, 33(2), 103-8.

For stars with atmospheres as complex as those of Miras, determination of fundamental stellar parameters remains a challenge. Occurrence of water "shells" and their implication on the interpretation of the angular diameter measurements will be discussed in this talk. The role of a spectrophotometric index of water in estimating the continuum diameter will be highlighted.

2 illus, 10 ref