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SU Lyn, a star that ostensibly appears to be an unremarkable late M type giant, has recently been proposed to be a symbiotic star largely based on its hard X-ray properties. The star does not display, in low-resolution optical spectra, the high excitation lines typically seen in the spectra of symbiotic stars. In the present work, UV, optical, and near-infrared observations are presented, aimed at exploring and strengthening the proposed symbiotic classification for this star. Our Far-UV 1300-1800Å spectrum of SU Lyn, obtained with the ASTROSAT mission’s UVIT payload, shows emission lines of Si IV, C IV, OIII and N III in a spectrum typical of symbiotic stars. The UV spectrum robustly confirms SU Lyn’s symbiotic nature. The detection of high excitation lines in a high-resolution optical spectrum further consolidates its symbiotic nature. As is being recognized, the potential existence of other similar symbiotic systems could significantly impact the census of symbiotic stars in the galaxy.

The process of beaconing used to gather information about position of sensors consumes extra energy due to unnecessary transmissions. In this paper, we propose a position-based beaconless routing (PBR) algorithm for wireless sensor networks that finds the path from source sensor to destination sensor and reduces the unnecessary transmissions. The next forwarder selection and packet forwarding algorithms are presented. Mathematical analysis of distribution of sensors in forward area, expected distance between sender and next forwarder, and average number of successful hops is provided. PBR uses distance and angle based neighbor selection at each forwarding step. It should be noted that PBR does not require use of extensive broadcast to select next forwarder sensor. The proposed protocol is simulated on MATLAB platform. Simulation results show that PBR performs better than LAR1, MFR, and GEDIR in terms of number of transmissions, end-to-end delay and consequently the energy consumption.

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Mt. Abu Faint Object Spectrograph and Camera (MFOSC-P) is an in-house developed instrument for Physical Research Laboratory (PRL) 1.2m telescope at Mt. Abu India, commissioned in February 2019. Here we present the first science results derived from the low resolution spectroscopy program of a sample of M Dwarfs carried out during the commissioning run of MFOSC-P between February-June 2019. M dwarfs carry great significance for exoplanets searches in habitable zone and are among the promising candidates for the observatory's several ongoing observational campaigns. Determination of their accurate atmospheric properties and fundamental parameters is essential to constrain both their atmospheric and evolutionary models. In this study, we provide a low resolution (R∼500) spectroscopic catalogue of 80 bright M dwarfs (J<10) and classify them using their optical spectra. We have also performed the spectral synthesis and χ 2 minimisation techniques to determine their fundamental parameters viz. effective temperature and surface gravity by comparing the observed spectra with the most recent BT-Settl synthetic spectra. Spectral type of M dwarfs in our sample ranges from M0 to M5. The derived effective temperature and surface gravity are ranging from 4000 K to 3000 K and 4.5 to 5.5 dex, respectively. In most of the cases, the derived spectral types are in good agreement with previously assigned photometric classification.

We report results obtained from the optical and X-ray studies of the Be/X-ray binary 1A 0535+262/HD 245770 during the 2020 October giant X-ray outburst, using the 1.2 m telescope at Mount Abu Infrared observatory and AstroSat, respectively. The peak flux of the outburst was recorded to be ∼11 Crab in the 15–50 keV range, the highest ever observed from the pulsar. We performed optical observations in the 6000–7200 Å band before, during, and after the outburst to investigate the evolution of the circumstellar disc of the Be star between 2020 February and 2022 February. Our optical spectra exhibit prominent emission lines at 6563 Å (H i), 6678 Å (He i), and 7065 Å (He i). We found a significantly variable Hα line in the spectra. The single-peaked line profile appeared asymmetric with broad red- & blue-wings in the data before and during the outburst. The post-outburst observations, however, resulted in a double-peaked profile with asymmetry in the blue-wing. Our observations before the outburst confirmed a larger Be disc that decreased in size as the outburst progressed. Furthermore, the observed variabilities in the Hα line profile and parameters suggest the presence of a highly misaligned, precessing, and warped Be disc. AstroSat observation of the pulsar detected pulsations at ∼103.55 s in the light curve up to 110 keV. We found strongly energy-dependent pulse profiles with increasing contribution of the pulsing component in hard X-rays. The broadband spectral fitting in the 0.7-90.0 keV range confirmed the presence of the known cyclotron resonance scattering feature at ∼46.3 keV.

In recent years, we have seen unprecedented growth in the area of Online Social Networking (OSN) that is still keeping on day by day. Social networking websites such as Facebook, Google+, and Twitter are using widely by people to share personal and public information with friends, coworkers, colleagues, family and even with strangers .Facebook, one of the most popular social network sites, has million of active users and billions of pieces of content or data that use daily like web links, news stories, blog posts, notes, photo albums, etc. shared each month. To protect such kind for huge or big data or information need more secured and flexible access control model. There are so many access control policies are available for controlling online social network, but all social networking sites like Facebook or Twitter has their own access control mechanism that is not standard and still not more secured or flexible. To protect such kind of publically oriented user data need more dynamic access control model. In order to protect OSN, in this paper an innovative or dynamic access control framework for social networking systems using semantic web ontology has been proposed which addresses the protection of semantic-rich information in a knowledge base ontology