We present the pulse arrival times and high-precision dispersion measure estimates for 14 millisecond pulsars observed simultaneously in the 300 $-$ 500 MHz and 1260 $-$ 1460 MHz frequency bands using the upgraded Giant Metrewave Radio Telescope. The data spans over a baseline of 3.5 years (2018-2021), and is the first official data release made available by the Indian Pulsar Timing Array collaboration. This data release presents a unique opportunity for investigating the interstellar medium effects at low radio frequencies and their impact on the timing precision of pulsar timing array experiments. In addition to the dispersion measure time series and pulse arrival times obtained using both narrowband and wideband timing techniques, we also present the dispersion measure structure function analysis for selected pulsars. Our ongoing investigations regarding the frequency dependence of dispersion measures have been discussed. Based on the preliminary analysis for five millisecond pulsars, we do not find any conclusive evidence of chromaticity in dispersion measures. Data from regular simultaneous two-frequency observations are presented for the first time in this work. This distinctive feature leads us to the highest precision dispersion measure estimates obtained so far for a subset of our sample. Simultaneous multi-band upgraded Giant Metrewave Radio Telescope observations in 300 $-$ 500 MHz and 1260 $-$ 1460 MHz are crucial for high-precision dispersion measure estimation and for the prospect of expanding the overall frequency coverage upon the combination of data from the various Pulsar Timing Array consortia in the near future. Parts of the data presented in this work are expected to be incorporated into the upcoming third data release of the International Pulsar Timing Array.

We introduce pinta, a pipeline for reducing the upgraded Giant Metre-wave Radio Telescope (uGMRT) raw pulsar timing data, developed for the Indian Pulsar Timing Array experiment. We provide a detailed description of the workflow and usage of pinta, as well as its computational performance and RFI mitigation characteristics. We also discuss a novel and independent determination of the relative time offsets between the different back-end modes of uGMRT and the interpretation of the uGMRT observation frequency settings and their agreement with results obtained from engineering tests. Further, we demonstrate the capability of pinta to generate data products which can produce high-precision TOAs using PSR J1909 $-$ 3744 as an example. These results are crucial for performing precision pulsar timing with the uGMRT.

In this paper, we present our study on multi-frequency scatter-broadening observations of a large sample of pulsars, made using the Ooty Radio Telescope (ORT) and the Giant Metrewave Radio Telescope (GMRT). For each pulsar, the scatter-broadening time scales (τsc) have been estimated at different observing frequencies and the dependence of τsc with the observing frequency, i.e., the frequency scaling index (α) has been obtained. We report estimates of α for a set of 39 pulsars, of which 31 are completely new and provide the first-time measurement on about 50% of the sample. This enhanced sample suggests that almost 65% of the pulsars have an α much lower than the conventional value of 4.4 for a Kolmogorov type turbulence spectrum, and a considerably large scattering strength. An increase in scattering strength is observed with the distance to the pulsar in the Galaxy.

Zinc potassium phosphate hexahydrate (ZnKPO4.6H2O) (abbreviated as ZPPH) single crystal is grown by reacting Potassium dihydrogen phosphate with Zinc Sulphate in equimolar ratio by slow evaporation. This compound crystallizes in the acentric orthorhombic symmetry class (space group Pmn21) and possesses photo induced optical second harmonic generation. The laser induced surface damage threshold for the grown crystal was measured as 1.7 × 1012 mJ/cm2 with Nd:YAG laser assembly which is of the same order as that of the reference KDP used in our experiment. The temperature dependent second harmonic generation studies were also carried out from room temperature to liquid helium temperature and the anomalies at low temperature qualifies this material as efficient low temperature optical switchers.

A short term survey to quantify the number of marine mammals incidentally caught, and interviews to gain perceptions of local fishers towards issues of by-catch, were conducted. A total of 44 cetaceans was recorded as incidental catches at Chennai, Kakinada and Mangalore fishing harbours during 80 days of observation. Six species of dolphins and one species of porpoise were recorded. The spinner dolphin Stenella longirostris was the most frequently caught (38.6%), followed by the finless porpoise Neophocaena phocaenoides (31.8%). Gill-nets and purse seines operated from motorized boats accounted for the entire by-catch. It is estimated that 9000–10,000 cetaceans are killed by gill-nets every year along the Indian coast. The intricacies and possibilities of reducing cetacean kills by gill-nets are discussed in this paper.

Using ethanol as a solvent p-aminoazobenzene (p-AAZB), an organic nonlinear optical crystal having good optical quality was grown by slow evaporation solution technique. Structural and optical properties were studied by applying XRD and UV-Vis spectroscopy. The measurement of the second harmonic generation was performed using the fundamental Nd:YAG 10 ns laser beam with wavelength 1.064 μm. Dependence of the second order susceptibilities for the two principal second order susceptibility tensor components d 14 and d 25 with the simultaneously applied dc- and UV-laser fields were investigated and discussed.