003391   Sreekumar P (NO, ISRO Satellite Centre, Bangalore-560 017, Email: pskumar@isac.ernet.in]) : ASTROSAT observations : complementary studies from ground. Bull Astr Soc India 2005, 33(2), 253-8.

Since the advent of the satellite era, X-ray astronomy and U V as-tronomy have advanced tremendously. The discovery of intense X-ray emission from accreting compact objects has permitted very detailed timing and spectral studies, leading to the important discovery of neutron stars and black holes as likely candidates driving these systems. Today, with the Rossi X-ray Timing Experiment (RXTE), Chandra x-ray Observatory (CXO) and XMM-Newton telescopes, X-ray astronomy provides the ideal tool to study regions of strong gravity, high magnetic field and high density in the Universe. Building on the success of earlier Indian piggyback space astronomy experiments, ASTROSAT is now being designed as India's first dedicated multiwavelength astronomy satellite to provide a broad-band space platform ranging from optical to hard X-ray. However, significant advancements in the ASTROSAT studies of many of the compact objects are expected from a wider multiwavelength observation platform including ground-based facilities at radio infrared optical amd TeV bands.

1 illus, 1 table, 3 ref

003390   Singh S K;Lalmani;Saini S;Gwal A K (Space Science Laboratory, Department of Physics and Electronics, Barka, , Bhopal-462 026, Email: sksingh_bpl@sancharnet.in) : First observations of extremely small dispersion whisters from Bhopal (L <126> 0.96), a low-latitude station. Curr Sci 2005, 89(5), 857-63.

First observations of extremely small dispersion (ESD) whistlers during night-time at low-latitude station, Bhopal (geomag. lat. 13<144> 47' N) are reported. The propagation mechanism of these ESD whistlers has been investigated in some detail. ESD whistler data presented have been collected during quiet period of 19-20 March 1999, which is a rare event. Results of the study of the characteristics of ESD whistlers are strongly indicative of non-ducted propagation for low-latitude night-time whistlers. It is proposed that these ESD whistlers are VLF waves radiated from the return stroke of the lightning discharge launched at the ionosphere with different initial wave normal angles. They are propagated upwards under either quasi-longitudinal conditions or as pro-longitudinal whistler modes with the dispersion of the order of 3 to 5 s^1/2, and are in complete contrast to the earlier findings of ducted propagation of low latitude night-time whistlers in the presence of equatorial anomaly. These ESD whistlers observed at Bhopal are found to obey the Eckersley law.

4 illus, 1 table, 59 ref

003389   Singh A K (NO, Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: asingal@prl.ernet.in ) : Radio astronomical imaging and phase information. Bull Astr Soc India 2005, 33(2), 245-52.

Some basic concepts in use for making astronomical observations at radio wavelengths are introduced. In particular the importance of phase information for imaging in radio astronomy is highlighted. Using simple examples it is demonstrated how phase information is much more essential than that even of amplitude for an image reconstruction from its Fourier components.

9 illus, 4 ref

003388   Sharma S;Sinha H S S (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: somkumar@prl.ernet.in) : Atmospheric soundings from Mount Abu. Bull Astr Soc India 2005, 33(2), 259-64.

An atmospheric science laboratory was set up at Gurushikhar, in the campus of PRL's Infrared observatory, in 1994. A variety of scientific instruments were housed in the atmospheric science laboratory to explore the Earth's ionosphere and neutral atmosphere. A powerful Nd-YAG laser based Lidar, a multi-wavelength all sky imaging system, Day-night-airglow photometer/spectrometer and a proton precession magnetometer are in operation along with a surface ozone sampler, a carbon mono-oxide analyzer and a UV radiometer (measures solar ultraviolet irradiance between 280 and 320 nm). The article highlights the neutral density and temperature measurements by the lidar as well as Atmospheric/Ionospheric parameters derived by other instruments.

5 illus, 13 ref

003387   Shah R R;Jog N S;Subhedar D V;Bobra A D; Rangooni H T;Mathur S N;Patwal P S;Rajpurohit G S;Jain J K (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: rajeshrs@prl.ernet.in) : The telescope control system at Mt. Abu infrared observatory. Bull Astr Soc India 2005, 33(2), 237-43.

The 1.2 m Mt. Abu telescope at Gurushikhar is operated by the Astronomy & Astrophysics Division of Physical Research Laboratory, Ahmedabad. The evolution of the telescope control system to its present form has been described. Along with the telescope, the auxiliary systems in the Gurushikhar Observatory also are upgraded from time to time and have been listed.

2 ref

003386   Sagar R;Misra K (NO, Aryabhatta Research Institute of Observational Sciences, Manora Peak, Nainital-263 129, Email: kuntal@aries.ernet.in) : Optical observations of GRB afterglows from India. Bull Astr Soc India 2005, 33(2), 209-17.

Optical observations of GRB afterglows provide information about GRB distances as well as their isotropic/non-isotropic nature of emission. More than 30 GRB fields have been probed by us during 1999 to 2003, out of which optical observations were obtained successfully for 14 GRB afterglows Important results derived from their light curves, spectral energy distribution and energetics are summarized. In general, early time flux decay constant (<126> 1.1)becomes steeper (<126> 2.4) at later times. Most of them are having relatively flat spectral index with values ranging from 0.7 to 1.0. Observations of these afterglows support the model ofnon-isotropic synchrotron emission from the center of the GRBs which reduces the budget of isotropic energy emission from <147> 10⁵³ ergs to <60> 10⁵² ergs, a value which is compatible with the current popular model of the origin of GRBs. Recent optical and radio observations of GRB030329 clearly indicates the association of Supernova with the GRB event.

3 illus, 2 tables, 39 ref

003385   Rawat A;Kembhavi A K (NO, Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune-411 007, Email: rawat@iucaa.ernet.in) : Morphological analysis of intermediate redshift galaxies using the HST/ACS GOODS survey. Bull Astr Soc India 2005, 33(2), 195-200.

Author have been involved in performing photometry and morphological analysis of a large, complete sample of galaxies in the intermediate redshift range using the high resolution images obtained by the Great Observatories Origins Deep Survey (GOODS) with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). Imaging data is available in 4 HST bands, viz. F435W, F606W, F775W and F850LP. The paper summarises the work that we have carried out so far and the future plans.

4 illus, 6 ref

003384   Rastogi S (Physics Department, D D U Gorakhpur University, Gorakhpur-273 009, Email: shantanu_r@hotmail.com) : Polycyclic aromatic hydrocarbons in interstellar medium. Bull Astr Soc India 2005, 33(2), 167-74.

Prolycyclic Aromatic Hydrocarbons (PAHs) are an important component of the Interstellar Medium (ISM). They are being used as probes for understanding of process and conditions of different astrophysical environments. The understanding of their IR spectra and its variations with PAH size and ionization state is useful in characterizing the ISM. Spectral features of model graphene sheets and also that of smaller PAH molecules are reported. The variation of intensity with charge state of the molecule shows that cations give a better correlation with observations. The relationship between changes in charge distribution with intensity changes upon ionization has been probed.

5 illus, 18 ref

003383   Mondal S (Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: soumen@prl.ernet.in) : Evidence of asymmetry in mira variable U Ori. Bull Astr Soc India 2005, 33(2), 97-102.

Near simultaneous, two high angular resolution observations by lunar occultation technique at the same wavelength (2.2 <109>m) but at different position angles (PA) result in two unique Uniform Disk (UD) angular diameters of Mira variable U Ori. UD angular diameter obtained from observations at Mt. Abu observatory is 11.9<145>0.3 milliarcsecond (mas) at PA 136<144> while from observations at TIRGO observatory UD value obtained is 15.14<145>0.05 mas at PA 75<144>. The source brightness profile derived from a model independent analysis shows an asymmetric spatial structure in both cases. Asymmetric structure of the source at higher spatial scale was also reported by several authors from OH and H₂O maser distribution at radio wavelengths; the source is more extended at PA of 30 - 60<144>. Furthermore, moderate level maximum optical intrinsic polarization of <126> 1-2 <37> at PA <155> 20<144> - 40<144> is also detected. All the evidences bring out the spatial asymmetry in U Ori.

2 illus, 1 table, 29 ref

003382   Lata S (Aryabhatta Research Institute of Observational Sciences, , Manora Peak, Naini Tal-263 129, Email: sneh@upso.ernet.in) : Mass function study of six open clusters Be 10, Be 67, To 5, Be 15, Be 71 and King 1. Bull Astr Soc India 2005, 33(2), 51-66.

The study have used the CCD data to determine the luminosity and mass function of six open clusters. Members of clusters are identified using photometric and statistical criteria. From these members, author has derived luminosity functions and determined the mass function slopes for the clusters under study. The mass function slopes for clusters Be 10, Be 67, To 5, Be 15, Be 71 and King 1 are 1.39<145>0.73, 3.41<145>0.98, 1.32<145>0.47, 1.35<145>0.46, 3.02<145>0.81 and 1.46<145>0.71 respectively. These slopes agree with the Salpeter value (x=1.35) within errors except for clusters Be 67 and Be 71 which have steeper slopes. The clusters Be 10, Be 67, To 5 and Be 15 show mass segregation while King 1 gives weak evidence of mass segregation and Be 71 does not show the effects of mass segregation. All the clusters under study are dynamically relaxed.

5 illus, 5 tables, 60 ref

003381   Khare P;Kulkarni V P;Lauroesch J T;Fall S M; York D G;Welty D E;Crotts A P S;Truran J W;Nakamura O (Physics Department, Utkal University, Bhubaneswar-751 004) : Evolution of metals and dust in the universe. Bull Astr Soc India 2005, 33(2), 219-24.

With the aim of determining the evolution of metals and dust in the universe, author have observed 8 Damped Lyman-alpha Absorbers (DLAs) with the Multiple Mirror Telescope and the Hubble Space Telescope at 0.1 <60> z <60> 1.5, including several absorbers discovered in the Sloan Digital Sky Survey. These measurements have more than doubled the sample of Zn and Cr measurements at z <60> 1.5 and added three measurements at z <60> 0.4, where none existed before. In contradiction with the predictions of most chemical evolution models, our data suggest that the global mean metallicity of DLAs, as measured by the gas phase abundance of Zn, at best evolves weakly with redshift over the range 0.09 <60> z <60> 3.9 and does not seem to rise to the solar level even at very low redshifts. The dust content, as determined by [Cr/Zn], does not show much change with redshift.

2 illus, 1 table, 8 ref

003380   Kembhavi A K;Barway S;Ravi Kumar C D (NO, Inter-University Centre for Astronomy and Astrophysics, Pune, Maharashtra, Email: akk@iucaa.ernet.in) : Lenticular and other galaxies. Bull Astr Soc India 2005, 33(2), 189-94.

Authors describe in the paper the surface photometry of a set of lenticular galaxies. Authors then consider important correlations between morphological parameters of the bulges of lenticulars and other types of galaxies.

3 illus, 12 ref

003379   Kameswara Rao N (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: nkrao@iiap.res.in) : Probing circumstellar dust formation through high resolution spectroscopy. Bull Astr Soc India 2005, 33(2), 159-65.

The existence of cool regions where dust can condense is explored in RCB stars at minimum.

4 illus, 20 ref

003378   Joshi U C;Ganesh S;Baliyan K S (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: joshi@prl.ernet.in ) : Polarimetric study of comets from Mt. Abu observatory. Bull Astr Soc India 2005, 33(2), 225-31.

The sunlight is scattered by the dust grains present in the coma and tail of comets which makes it visible. The scattered sunlight is characteristically polarized with degree of polarization generally depending upon the phase angle, wavelength of the incident light, shape and size distribution of the scattering particles and refractive indices of the particles. High precision pho-topolarimetric observations at several wavebands and phase angles were made on several bright comets during the last decade using the facilities at Mt. Abu observatory with the aim to study the characteristics of the dust grains in the comets. All these comets were bright comets and found to belong to high polarization class of comets. At low phase angles comets show significant negative polarization indicating the grains to be regolith consisting of monomers of sub micron size.

2 illus, 26 ref

003377   Jog C J (Department of Physics, Indian Institute of Science, Bangalore-560 012, Email: cjjog@iisc.ernet.in) : Advanced mergers of galaxies: Luminosity profiles and dynamics. Bull Astr Soc India 2005, 33(2), 201-8.

Author have analyzed the near-IR K_s-band data from the 2MASS archival database for a large sample of twenty-seven galaxies that show signs of interaction but have a single nucleus. Surprisingly, half of these advanced mergers of galaxies show luminosity profiles which have an outer exponential fall-off with radius, as in a spiral galaxy (Chitre and Jog 2002). The kinematical data for two of these, Arp 224 and Arp 214, available from the HYPERCAT database were used and these show kinematics similar to elliptical galaxies with the random motion dominating the rotation (Jog and Chitre 2002). The origin of the mixed properties shown by these mergers is a puzzle. To understand these systems, we have recently studied the dynamics of mergers via N-body simulations for unequal-mass mergers covering a new range of galaxy mass ratios 4:1-10:1 (Bournaud, Combes, and Jog 2004). Author show that such mergers naturally result in remnants that have the mixed properties as we have observed from the 2MASS data analysis. The transition between elliptical and disk-like remnants is found to occur over a narrow range of galaxy mass ratios 3:1-4.5:1 (Bournaud, Jog and Combes 2005).

3 illus, 12 ref

003376   Hasan P (NO, IUCAA, Post Bag 4, Ganeshkhind, Pune-411 007, Email: priya@iucaa.ernet.in) : Near infrared photometry of the young clusters NGC 1960, NGC 2453 and NGC 2384. Bull Astr Soc India 2005, 33(2), 151-7.

Gives a brief description of the observations and analysis of the young star clusters NGC 1960, NGC 2453 and NGC 2384 observed in the near infrared bands at the Mt Abu Infrared Observatory, Gurushikhar in February 2000. Estimates of distance and age for these clusters for the first time using JHK data have been obtained. The colour-magnitude diagrams of these clusters have been extended to the fainter end as far as possible. The observed data was found to agree reasonably well with that obtained by 2MASS. A more detailed paper will be published elsewhere.

3 illus, 2 tables, 14 ref

003375   Gupta Y;Mitra ;Green D A;Acharyya A (National Centre for Radio Astrophysics, Tata Institute of Fundamental Research, Pune University Campus, Pune-411 007, Email: ygupta@ncra.tifr.res.in) : The discovery of PSR J1833-1034: the pulsar associated with the supernova remnant G21.5-0.9. Curr Sci 2005, 89(5), 853-6.

Authors has reported the discovery of a young pulsar associated with the supernova remnant G21.5-0.9, using the Giant Metrewave Radio Telescope (GMRT) located near Pune, India. Discovered at a frequency of 610 MHz, PSR J1833-1034 has a period of 61.86 ms and a period derivative of 2.0 x 10^-13, making it similar to other known young pulsars. The characteristic age of the pulsar is <155> 4900 yrs, somewhat higher than estimates for the age of the remnant, but not incompatible with it. The pulsar has a spin-down luminosity of 3.3 X 10³⁷ erg s^-1, which is the second highest amongst all the known galactic pulsars.

1 illus, 1 table, 24 ref

003374   Gupta R;Ashok N M;Singh H P;Ranade A C (IUCAA, , Post Bag 4, Ganeshkhind, Pune-411 007, Email: rag@iucaa.ernet.in) : A near-IR stellar spectral library in the H band using the Mt. Abu telescope. Bull Astr Soc India 2005, 33(2), 175-79.

Author present an H band near-infrared (NIR) spectral library of 135 solar type stars covering spectral types 05-M3 and luminosity classes I-V as per MK classification. The observations were carried out with 1.2 meter Gurushikhar Infrared Telescope (GIRT), at Mt. Abu, India using a NICMOS3 HgCdTe 256 x 256 NIR array based spectrometer. The spectra have a moderate resolution of 1000 (about 16 Angustrum) at the H band and have been continuum shape corrected to their respective effective temperatures. A detailed paper describing all the aspects of this spectral library has been published in Ranade et. al. (2004).

3 illus, 5 ref

003373   Ghosh S K (NO, Tata Institute of Fundamental Research, Mumbai-400 005, Email: swarna@tifr.res.in) : Star formation studies at TIFR. Bull Astr Soc India 2005, 33(2), 133-9.

Studies of Galactic star forming regions being carried out at TIFR, is summarized. The techniques and typical results from these studies have been described briefly, which include : the balloon borne far infrared mapping in broad photometric bands (150 & 210 <109>m) as well as spectroscopic imaging in the fine structure [C II] line at 158 <109>m; near infrared imaging in broad and narrow bands using the Mt. Abu Infrared Telescope & Himalayan Chandra Telescope; high resolution radio interferometric imaging in the 330-1400 MHz bands using GMRT; and use of data products from international space missions like Midcourse Space Experiment (MSX).

7 illus, 9 ref

003372   George K;Chandrasekhar T (Physical Research Laboratory, , Ahmedabad-380 009, Email: koshyg@prl.ernet.in) : Infrared spectroscopy of Jovian aurorae. Bull Astr Soc India 2005, 33(2), 233-6.

Authors reports on the detection at Mt. Abu of H⁺₃ molecular ion emissions in the near infrared spectra of the northern auroral zone of Jupiter. These H⁺₃ transitions are of rotational-vibrational origin and are due to the dynamics of Jovian auroral ionosphere located mainly at high Jovian latitudes, which confirms their magnetospheric origin. The main overtone transition at 2.093 <109>m and several other transitions including that of H₂ have been detected.

2 illus, 2 tables, 5 ref

003371   Ganesh S;Joshi U C;Baliyan K S;Omont A;Simon G (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: shashi@prl.res.in) : Multiwavelength study of the inner regions of the Milky Way Galaxy. Bull Astr Soc India 2005, 33(2), 145-50.

The inner regions of the Milky Way have received a lot of attention in recent years. Multiwavelength observations have been made at varying spatial, temporal and spectral resolutions. Author have studied the inner regions of the Milky Way using data from the Infrared Space Observatory at mid infrared wavelengths, DENIS and 2MASS at near infrared wavelengths, etc. Author summarize results obtained from the studies. It discusses in particular the M16 star forming region for which complementary near infrared observations were made using the PRL NICMOS array on the 1.2 m telescope at the Mt Abu IR Observatory.

2 illus, 3 ref

003370   Chandrasekhar T (Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: chandra@prl.ernet.in) : Lunar occultations in the near infrared: Achievements and new challenges. Bull Astr Soc India 2005, 33(2), 87-96.

A brief review of the lunar occultation program in the near infrared for high angular resolution study of bright IR sources carried out at PRL in the last decade is presented. The development of the two channel Fast IR photometer is described. Major results pertaining to circumstellar dust structures surrounding occulted objects like IRC+10216 and WR104 are outlined. The challenges for the future in observing lunar occultations in the L band and in the use of IR arrays for occultation work are discussed.

7 illus, 18 ref

003369   Chakrabarti S K (NO, S N Bose National Center for Basic Sciences, JD Block, Salt Lake, Kolkata-700 098, Email: chakraba@bose.res.in) : A recent multi-wavelength campaign to observe the microquasar SS433. Bull Astr Soc India 2005, 33(2), 109-15.

Author presents a summary of the recent multiwavelength campaign made in September-October, 2002, to observe SS 433. Author used the Giant Meter Radio Telescope (GMRT) for radio observation, 1.2 meter Physical Research Laboratory Infra-red telescope at Mt Abu for IR, 1 meter Telescope at the State Observatory, Nainital for Optical photometry, 2.3 meter optical telescope at the Vainu Bappu observatory for spectrum and Rossi X-ray Timing Explorer (RXTE) Target of Opportunity (TOO) for X-ray observations. Sharp variations in intensity in time-scales of a few minutes in X-rays, IR and radio wavelengths have been discovered. It has been also discover a delay of about two days between IR and Radio. Double Fe line profiles which corresponded to red and blue components of the relativistic jet have been found in X-ray data. Author presents the broadband spectrum averaged over the campaign duration.

3 illus, 14 ref

003368   Banerjee D P K (Physical Research Laboratory, , Ahmedabad-380 009, Email: orion@prl.ernet.in) : Studies of the peculiar nova V4332 Sgr. Bull Astr Soc India 2005, 33(2), 81-6.

Author discuss about recent observations of the interesting but enigmatic nova-like variable V4332 Sgr. The object shows a remarkably rich near-infrared and optical spectrum with several unusual spectral features generally not seen in classical novae. Results support the emerging consensus that V4332 Sgr, and its possible analog V838 Mon, constitute a new class of eruptive variables. Results indicate that a cold circumstellar disc containing gas, dust and water ice surrounds the object. Though the cause of the outburst in these objects is not completely understood, we propose a plausible planetary-capture scenario to explain the eruption of V4332 Sgr.

4 illus, 17 ref

003367   Baliyan K S;Joshi U C;Ganesh S (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: baliyan@prl.ernet.in) : Monitoring of AGNs for variability from MIRO. Bull Astr Soc India 2005, 33(2), 181-8.

As a long term programme, a sample of blazars is being monitored from Mt Abu Infrared Observatory (MIRO). Blazars are the radio-loud AGNs with polarized, highly luminous and rapidly variable non-thermal continuum emission ranging from radio to <103> rays, from a relativistic jet. The emission shows variability at several time scales. Radio through <103>-ray spectral energy distribution (SED) of blazars exhibits two broad humps- first at UV/optical, considered to be due to synchrotron emission from the relativistic electrons, and second one in the region extending from X-ray to <103>-rays whose origin is less understood. Long term multi-wavelength monitoring of the blazars for variability is the key to obtain information on the geometry of the jets and the physical processes responsible for the high energy emissions. Here author report monitoring of several blazars using 1.2 m IR telescope and discuss recent results on some of them. In particular, PKS0716+714 and 3C66A have shown intense activity and continued in bright phase during 2003-04, drawing worldwide attention for a co-ordinated monitoring campaign.

2 illus, 26 ref

003366   Ashok N M (Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: ashok@prl.ernet.in) : Infrared study of the first identified helium nova V445 puppis. Bull Astr Soc India 2005, 33(2), 75-9.

The eruptive variable V445 Puppis has been proposed by author as the first observed Helium nova. The absence of hydrogen lines in the early optical spectra showed the peculiar nature of this object. Author has observed V445 Pup for three months following its discovery at near infrared wavelengths. Observations confirm the absence of hydrogen lines in V445 Pup and exhibit several prominent emission features. Based on the identification of several CI lines in J and H bands we suggested that V445 Pup is a prospective candidate for theoretically hypothesized Helium nova. Subsequently Kato and Hachisu (2003) have done modeling of its low amplitude light curve in the context of helium nova outburst and show that the observed low amplitude light curve of V445 Pup is reproduced by thermonuclear runaway in helium rich material on a massive white dwarf in a close binary system.

2 illus, 14 ref

003365   Anandarao B G (NO, Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: anand@prl.ernet.in) : Near-infrared photometric and spectroscopic studies on star forming regions. Bull Astr Soc India 2005, 33(2), 125-31.

Author have initiated a programme to study near-infrared photometry and spectroscopy of low and high mass star forming regions and young stellar objects using the HgCdTe 256x256 array camera/spectrograph at the 1.2 m telescope. Author describe here some of the significant results obtained under this programme on (i) a low mass T Tauri type pre-main sequence(PMS) star; (ii) an intermediate mass star forming region; and (iii) two high mass star forming regions.

2 illus, 23 ref

003364   Anandarao B G (Astronomy & Astrophysics Division, Physical Research Laboratory, Ahmedabad-380 009, Email: anand@prl.ernet.in) : Imaging fabry-perot spectrometric studies of velocity fields in gaseous nebulae. Bull Astr Soc India 2005, 33(2), 117-23.

In order to study the spatio-kinematics of extended gaseous nebulae such as the HII regions associated with giant molecular clouds and planetary nebulae, author had designed and built an Imaging Fabry-Perot Spectrometer for the 1.2m Mt Abu Telescope. Describes here some of the significant scientific results that came out of these studies in the past one decade at Mt Abu.

2 illus, 23 ref

002213   Zade M;Ray S S;Dutta S;Panigrahy S (Agro-Ecology and Mgmt Div ARG/RESIPA Space Applics Cent, Indian Space Res Organisation, Ahmedabad-380 015, Email: ssray@sac.isro.org) : Analysis of runoff pattern for all major basins of India derived using remote sensing data. Curr Sci 2005, 88(8), 1301-5.

An attempt has been made to quantify and analyse intra-and inter-basin runoff potential for all basins of India using multi-date remote sensing data, curve number approach and normal rainfall data of 376 stations. Analysis showed that the highest runoff depth (1812 mm) was observed in the Brahmaputra basin (including Barak and other rivers) and the lowest (210 mm) in the Luni and rivers of Saurashtra basin. The Brahmputra basin, occupying only 8% of the geographical area of the country, provided around 19% of total runoff. In almost all basins, 90% runoff occurs during the five-month period starting from June. The runoff in the Brahmaputra, Narmada and Mahanadi basins responded well to rainfall, i.e. high runoff coefficient, whereas low runoff coefficient was found in the Cauvery basin.

3 illus, 1 table, 10 ref

002212   Tiwari C M;Tiwari D P;Shrivastava P K (Dep of Phys, A P S Univ, Rewa-486 003) : Anomalous behaviour of cosmic ray diurnal anisotropy during descending phase of the solar cycle-22. Curr Sci 2005, 88(8), 1275-8.

Large anomalies have been detected in the characteristics of daily variation of cosmic rays during 1993 and 1994. The years 1993 and 1994, which fall in the descending phase of solar activity cycle-22, show the period of anomalous variation of diurnal waves particularly in the diurnal time of maximum. In 1992, the diurnal pase shifted to later hours at first, but anomalously recovered in 1993 and 1994, and then again shifted to early hours continuously since 1994 to 1997. The recovery of phase in 1993 and 1994 is quite significant and anomalous, and is not associated with any anomalous change in diurnal amplitude, which remains constant. Dependence of diurnal vector on the variation of Ap values are studied.

4 illus, 16 ref

001081   Tiwari C M;Tiwari D P;Agrawal S P (Dep of Phys, A P S Univ, Rewa-486 003) : Relationship of first two harmonics of cosmic ray daily variation with solar activity. Indian J Radio Space Phys 2004, 33(2), 95-8.

Systematic correlative studies have been performed since long to establish the relationship of cosmic ray anisotropy with solar activity parameters, and the studies are extended for the recent periods. In the analysis, yearly averages of sunspot number R_z have been used to correlate with the yearly average amplitudes and phases of the first two harmonics of the daily variation of cosmic rays derived from the data of stations Kiel and Tokyo, representative of low and high cut-off rigidity respectively. Significant positive correlations, both for the diurnal amplitude and phase, have been observed. Similarly, positive correlations with sunspot numbers are also noticed in case of semi-diurnal phase for both the stations. However, the semi-diurnal amplitudes of the daily variation of cosmic rays show small negative correlation with R_z.

4 illus, 12 ref

001080   Renuka G;Raji R;Sindhu;Venugopal C (Dep of Phys, Univ of Kerala, Kariavattom-695 581) : Relation between shear-zone thickness, boundary layer instability and plasmoids in geomagnetosphere. Indian J Radio Space Phys 2004, 33(2), 99-103.

A study of the dependence of shear-zone thickness on the growth rate and frequency of Kelvin- Helmholtz instability (KHI) in the shear-zone between low latitude boundary layer (LLBL) and central plasma sheet (CPS) is carried out. It is found that the growth rate and frequency are maximum for a shear-zone of minimum thickness. The amplitude of plasma sheet (PS) oscillation is found to be positive as the PS thickness increases and is maximum when PS thickness is 2R_E (1R_E= 6378 km) for a shear-zone of minimum thickness. This perturbation generates tearing mode instability (TMI) which leads to the formation of plasmoids.

2 illus, 2 tables, 11 ref

001079   Rahaman F;Chakraborty S;Begam N;Hossain M;Das S (Dep of Math, Jadavpur Univ, Calcutta-700 032) : Bianchi type VI_o string cosmology in lyra geometry. Bull Calcutta Mathl Soc 2005, 97(1), 49-58.

Some cosmological solutions for massive strings are obtained in Bianchi-VI_o space time within the framework of Lyra geometry. The physical behaviour of this model has also been discussed.

13 ref

001078   Mulgi S N;Vani R M;Hunagund P V;Hadalgi P M (Dep of Appl Electron, Gulbarga Univ, Gulbarga-585 106) : A compact broadband gap-coupled microstrip antenna. Indian J Radio Space Phys 2004, 33(2), 139-41.

A method for improving the bandwidth of microstrip antenna by incorporating a common parasitic element, which is gap-coupled to the radiating edges of rectangular patches, is described. This technique makes the proposed antenna structure compact in size with a bandwidth of around 22%. The theoretical bandwidth and input impedance for the proposed configuration are also evaluated. Experimental and theoretical results are found to be in good agreement.

5 illus, 2 tables, 10 ref

001077   Lakshmanan M (Dep of Phys, Cent for Nonlinear Dynamics Bharathidasan Univ, Tiruchirapalli-620 024, Email: lakshman@cnld.bdu.ac.in) : Nonlinear dynamics: Challenges and perspectives. Pramana J Phys 2005, 64(4), 617-32.

The study of nonlinear dynamics has been an active area of research since 1960s, after certain path-breaking discoveries, leading to the concepts of solitons, integrability, bifurcations, chaos and spatio-temporal patterns, to name a few. Several new techniques and methods have been developed to understand nonlinear systems at different levels. Along with these, a multitude of potential applications,,of nonlinear dynamics have also been enunciated. In spite of these developments, several challenges, some of them fundamental and others on the efficacy of these methods in developing cutting edge technologies, remain to be tackled. A brief personal perspective of these issues is presented.

2 tables, 29 ref

001076   Das B N;Arun Gayen (Dep of Electron and Electl Communs Engng, Indian Inst of Technol, Kharagpur-721 302) : Potential and field distribution inside an axially split cylinder. Indian J Radio Space Phys 2004, 33(2), 130-8.

The paper presents a method of evaluation of potential and field distribution inside an axially split cylinder, one part of which is insulated and other maintained at ground potential. The Laplace's equation expressed in cylindrical polar co-ordinates is solved assuming no axial variation, and using boundary condition for the potential. The radial and angular components of the field intensity are found using the appropriate derivative operator in the cylindrical co-ordinate system. The condition under which the radial field is maximum, is derived in terms of angular widths of the conductors. If the radial field intensity exceeds the breakdown limit, the resulting breakdown of the gas leads to plasma generation inside the structure.

4 illus, 3 tables, 7 ref

001075   Chopra R;Verma V K;Sharma P K (Punjab Remote Sens Cent, , Ludhiana) : Application of remote sensing to establish a relationship between geomorphology and flood prone areas in Sangrur district, Punjab. Bull Indian Geol Ass 2004, 37(1-2), 67-72.

The ability of space technology to provide basic information in space, time and frequency domains has been proved to be very useful in providing permanent records by mapping and monitoring of natural resources and managing flood dynamics. Multidate satellite remote sensing data have been used to analyse landforms in Sangrur district. In July 1993, floods were at their devastating worst in Punjab for the second time since September 1988. In the study an attempt has been made to establish a relationship between geomorphology and flood prone areas in Sangrur district.

3 illus, 8 ref

001074   Calla O P N;Baruah A;Das B;Mishra K P;Kalita M;Haque S S (Int Cent for Radio Sci, OM NIWAS, A-23, Shastri Nagar, Jodhpur-342 003) : Variability of dielectric constant of dry soil with its physical constituents at microwave frequencies and validation of the CVCG model. Indian J Radio Space Phys 2004, 33(2), 125-9.

In the designing of active and passive sensor for microwave remote sensing of soil, its electrical parameters like scattering coefficient and emissivity play a vital role. One of the important parameters on which these two depend is the value of the dielectric constant that again varies with the physical constituents of the soil. In the paper, an attempt has been made to study the variability of the dielectric constant of dry soil with its physical constituents. The soil samples are taken from different parts of northern India and variations of dielectric constant as observed in the X-band are presented here. The CVCG model, generated to compute the dielectric constant for dry soil from its physical constituents has also been validated.

3 illus, 3 tables, 6 ref

001073   Balakrishnan R (The Inst of Math Sci, C I T campus, Chennai-600 113, Email: radha@imsc.res.in) : Space curves, anholonomy and nonlinearity. Pramana J Phys 2005, 64(4), 607-15.

Using classical differential geometry, authour discusses the phenomenon of anholonomy that gets associated with a static and a moving curve. Author has obtain the expressions for the respective geometric phases in the two cases and interpret them. Author shows that there is a close connection between anholonomy and nonlinearity in a wide class of nonlinear systems.

25 ref

023083   Subramaniam A;Mathew B;Kartha S S (NO, Indian Institute of Astrophysics, Bangalore-560 034, Email: purni@iiap.res.in) : Star formation in the region of young open cluster - NGC 225. Bull Astr Soc India 2006, 34(4), 315-25.

NGC 225 is believed to be a 120 Myr old open cluster located at <126> 650 pc. Eight stars with H_α emission are found to be located around the cluster, of which two are probable Herbig Be stars, indicating a very young age for the cluster. To explore whether the Herbig Be stars, which are pre-main sequence (PMS) stars are part of this cluster, cluster parameters were re-estimated using optical (UBV) pg and 2MASS JHK photometry. Combined the above data to detect the presence of any possible PMS stars in the cluster region. Among the identified 28 proper motion members, 15 stars were found to have near-infrared (NIR) excess indicating that they are PMS stars. Also, most of the upper MS stars were found to show NIR excess suggesting that the brighter proper motion member stars have not yet reached the MS. PMS isochrones were used to estimate the age of stars with NIR excess and is found to be between 0.5-10 Myr. Thus, the cluster NGC 225 is a very young cluster, younger than 10 Myr and its age is not 120 Myr as previously believed. It was proposed that a recent star formation has resulted in the formation of NGC 225, two Herbig Be stars, stars with H_α emission, dust lanes and nebulosity in the vicinity of the cluster.

5 illus, 17 ref

023082   Parthasarathy M;Branch D;Baron E;Jeffery D J (Indian Institute of Astrophysics, , Koramangala, Bangalore) : On the progenitor of supernova 1987A. Bull Astr Soc India 2006, 34(4), 385-91.

A previously unpublished ultralow-dispersion spectrum of Sand-uleak -69 202, the stellar progenitor of SN 1987A, is presented and the uncertain presupernova evolution of Sanduleak -69 202 is discussed.

2 illus, 35 ref

023081   Joshi B C;Ramakrishna S (National Centre for Radio Astrophysics (TIFR), , Pune-411 007) : A software baseband receiver for pulsar astronomy at GMRT. Bull Astr Soc India 2006, 34(4), 401-12.

A variety of pulsar studies, ranging from high precision astrometry to tests for theories of gravity, require high time resolution data. Few such observations at more than two frequencies below 1 GHz are available. Giant Meterwave Radio Telescope (GMRT) has the unique capability to provide such multi-frequency pulsar data at low observation frequencies, but the quality and time resolution of pulsar radio signals is degraded due to dispersion in the interstellar medium at these frequencies. Such degradation is usually taken care of (by employing specialized digital hardware, which implement coherent dedispersion algorithm. In recent years, a new alternative is provided by the availability of cheap computer hardware. In this approach, the required signal processing is implemented in software using commercially off-the-shelf available computing hardware. This makes such a receiver flexible and upgradeable unlike a hardware implementation. The salient features and the modes of operation of a high time resolution pulsar instrument for GMRT based on this approach is described in this paper. The capability of the instrument is demonstrated by illustrations of test observations. Obtained the average profile of PSR B1937+21 at 235 MHz for the first time and this profile indicates a scattering timescale of about 300 μ. Lastly, the possible future extensions of this concept are discussed.

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023080   Hahn G;Mottola S;Sen A K;Harris A W;Kuhrt E; Mueller M (NO, Institute of Planetary Research, German Aerospace Center, (DLR) Rutherford Strabe 2, D-12489, Berlin, Germany) : Photometry of karin family asteroids. Bull Astr Soc India 2006, 34(4), 393-9.

Performes photometric observations in the V-band of two asteroids belonging to the Karin asteroid family, (11728) Einer and (93690) 2000 VE₂₁, using the 2-m Himalayan Chandra Telescope, Hanle and 2k x 4k pixels CCD imager. Obtaines measurements during two nights (November 25 and 26, 2005) which enabled information on the rotational periods and the lightcurve amplitudes of the asteroids to be derived. Also derived the absolute magnitudes H, improving previously published values. These observations were performed to complement the IR observations obtained for a set of Karin family asteroids with the Spitzer space telescope.

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023079   Green D A;Clemens M S;Alexander P;Cullen H; Nikolic B (Mullard Radio Astronomy Observatory, Cavendish Laboratory, , 19 J.J. Thomson Avenue, Cambridge CB3 OHE, United Kingdom) : Giant metrewave radio telescope limits oncool HI in galaxy groups. Bull Astr Soc India 2006, 34(4), 375-83.

Presents Giant Metrewave Radio Telescope 21-cm HI observations towards a sample of compact radio sources behind galaxy groups, to search for cool HI. The results-from high dynamic range spectra for 8 lines-of-sight through 7 galaxy groups-do not show any evidence for absorption by cool HI. At a resolution of 20 km s^-1, the optical depth upper limits obtained were between 0.0075 and 0.035 (3σ); these correspond to upper limits of a few times 10²³ m^-2 for the column density of any cool HI along these lines of sight (assuming a spin temperature of 100 K).

2 tables, 1 illus, 29 ref

022116   Yagoub M M (Geography Program, Humanities and Social Sciences College, United Arab Emirates Univ, Al AIn, P. O. Box 17771, UAE, Email: myagoub@uaeu.ac.ae) : Application of remote sensing and geographic information systems (GIS) to population studies in the gulf: a case of Al Ain city (UAE). J Indian Soc Remote Sens 2006, 34(1), 7-21.

Studies population distribution in Al Ain city in Eastern United Arab Emirates (UAE) through integration of remote sensing and Geographic Information System (GIS). The remote sensing data used in this study included high spatial resolution (1 m) IKONOS imagery of February 17, 2001. For the population related studies IKONOS data offers number of advantages over other satellite images, e.g. it has high spatial resolution, it covers a larger area per image, it cost less per km², and available on a more regular basis. Such characteristics provide a mechanism by which population estimates can be updated with high accuracy and better rate of frequency. The average difference between the population recorded in the 2001 and that estimated from IKONOS images for A 1 Ain city is found to be equal to 5%. GIS is used for modelling the relationship among population variables and shows result obtained. Empirical model analyses results of this study show that the overall density of the city is consistent with location theories, i.e., declining population density from the Central Business District (CBD). The trend of higher-income people living in peripheries of cities is evident worldwide as it is in Al Ain.

7 table, 6 illus, 34 ref

022115   Trimble V (Physics and Astronomy Dep, University of California, Irvine CA 92697-4575, USA) : The other backgrounds. Bull Astr Soc India 2006, 34(2), 167-87.

Significance of the cosmic microwave background or CMB (3K, thermal, relict, black body, isotropic, etc) radiation in confirming a hot big bang model of the early Universe and in setting precise values of many of the parameters of that model is widely known and has recently been enhanced by the results of three years of operation of the Wilkinson Microwave Anisotropy Probe (WMAP). There are, how-ever, also backgrounds of astrophysical and cosmological significance consisting of photons of other wavelengths, other forms of radiation, particles, and fields. Several predate the discovery of the CMB, while others are relatively recent discoveries. Explores the history of their predictions and discoveries and their cosmological and astrophysical implications as currently understood.

2 tables, 162 ref

022114   Limaye S;Warell J;Bhatt B C;Fry P M;Yound E F (Space Science and Engineering Centre, Univeristy of Wisconsin, Madison, WI 53706, US) : Multi-observatory observations of night-side of venus at 2.3 micron - atmospheric circulation from tracking of cloud features. Bull Astr Soc India 2006, 34(2), 189-201.

Observation of venus were made during 3 May to 11 May 2004 (117.4° - 125.7° phase angle) 3 July to 10 July, 2004 (132.5° - 125.1° phase angle) from the 1.2-metre Mt. Abu Telescope at Gurushikhar, Himalayan Chandra Telescope at Mt. Saraswati, Hanle and the Nordic Optical Telescope at La Palma, Canary Islands and the NASA/Infra Red Telescope Facility (IRTF) at Mauna Kea, Hawaii in J and K bands. While the sunlit crescent portion was saturated in the detector, the night-side shows discrete cloud features. These features are seen to evolve over time and are markers of the the atmospheric flow at or below km altitude above the surface. By combining multi-site observations, authors able to make measurements of zonal cloud velocities over baselines that are several hours long and get a better idea of the evolution of the features over time.

6 illus, 20 ref

022113   Karthikeyan B;Balachandra Kumar K; Rajamanickam N;Bagare S P (Physics Research Centre, VHNSN College, Virudhunagar 626 001) : Astrophysical molecule C N : vibronic transition probability parameters. Bull Astr Soc India 2006, 34(2), 203-9.

Astrophysical applications are broadened by the emerging consensus on the vibration-electronic (vibronic) transition probability parameters such as Fanck - Condon (FC) factors & r - centroids of some molecular species like CN, which could be useful in the identification of molecular lines and in the estimation of relative abundance of the species in various celestial bodies especially in the interstellar medium. Such important parameters, that is FC factors and r - centroids, have been computed by a reliable numerical integration procedure for the bands of E²∑⁺-X²∑⁺, D²∏_i-A²∏_i, E²∑⁺-A²∏_i, F²Δ_r-A²∏_i and J²Δ-A²JJ_i, systems of astrophysical molecule CN, using a suitable potential. for E - X system, the improved values of FC factors from the revised molecular constants are given along with the already reported values.