Rahul Biswas
A5020032349- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Pulsars and Gravitational Waves Research
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Scientific Research and Discoveries
- Oil Palm Production and Sustainability
- Distributed and Parallel Computing Systems
- Radio Astronomy Observations and Technology
- Spectroscopy and Chemometric Analyses
- Coastal wetland ecosystem dynamics
- Land Use and Ecosystem Services
- Vaccine Coverage and Hesitancy
- COVID-19 and Mental Health
- History and Developments in Astronomy
- Child Nutrition and Water Access
- Medical Device Sterilization and Disinfection
- HIV/AIDS Research and Interventions
- Urban Agriculture and Sustainability
- Conservation, Biodiversity, and Resource Management
- COVID-19 Pandemic Impacts
Medical College and Hospital, Kolkata
2025
Jackson State University
2025
R. G. Kar Medical College and Hospital
2017-2024
Stockholm University
2017-2024
KPC Medical College and Hospital
2002-2024
Tata Memorial Hospital
2024
West Bengal State Council of Technical Education
2024
AlbaNova
2018-2023
Khulna University
2018-2023
University of Washington
2015-2020
(Abridged) We describe here the most ambitious survey currently planned in optical, Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST have unique capability faint time domain. The design is driven four main themes: probing dark energy matter, taking an inventory Solar System, exploring transient optical sky, mapping Milky Way. wide-field ground-based system sited at Cerro Pach\'{o}n northern Chile. telescope 8.4 m...
Aims. We present cosmological constraints from a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z< 0.1), all three seasons (0.05 <z< 0.4), years (0.2 1), it totals 740 spectroscopically confirmed supernovae with high-quality light curves.
The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides 47 deg2 field of view and 8 s readout time, yielding more than an order magnitude improvement in speed relative to its predecessor survey, Factory. We describe design implementation observing system. ZTF data system at Infrared Processing Analysis Center near-real-time reduction identify moving varying objects. outline analysis...
A survey that can cover the sky in optical bands over wide fields to faint magnitudes with a fast cadence will enable many of exciting science opportunities next decade. The Large Synoptic Survey Telescope (LSST) have an effective aperture 6.7 meters and imaging camera field view 9.6 deg^2, be devoted ten-year 20,000 deg^2 south +15 deg. Each pointing imaged 2000 times fifteen second exposures six broad from 0.35 1.1 microns, total point-source depth r~27.5. LSST Science Book describes basic...
The Zwicky Transient Facility (ZTF), a public-private enterprise, is new time domain survey employing dedicated camera on the Palomar 48-inch Schmidt telescope with 47 deg$^2$ field of view and 8 second readout time. It well positioned in development astronomy, offering operations at 10% scale style Large Synoptic Survey Telescope (LSST) single 1-m class telescope. public surveys will cover observable northern sky every three nights g r filters visible Galactic plane night r. Alerts...
Abstract We present a public catalog of transients from the Zwicky Transient Facility (ZTF) Bright Survey, magnitude-limited ( m < 19 mag in either g or r filter) survey for extragalactic ZTF stream. introduce cuts on coverage, sky visibility around peak light, and other properties unconnected to nature transient, show that resulting statistical sample is spectroscopically 97% complete at <18 mag, 93% <18.5 75% <19 mag. summarize fundamental this population, identifying distinct...
We show that the number of observed voids in galaxy redshift surveys is a sensitive function equation state dark energy. Using Fisher matrix formalism we find error ellipses $w_0-w_a$ plane when energy assumed to be form $w_{CPL}(z)=w_0 +w_a z/(1+z)$. forecast with ESA Euclid satellite and NASA WFIRST mission, taking into account updated details reach accurate estimates their power. The theoretical model for based on matches between abundances simulations analytical prediction. To take...
The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field, ground-based survey system that will image the sky in six optical bands from 320 to 1050 nm, uniformly covering approximately $18,000$deg$^2$ of over 800 times. LSST currently under construction on Cerro Pachón Chile, and expected enter operations 2022. Once operational, explore wide range astrophysical questions, discovering "killer" asteroids examining nature Dark Energy. generate average 15 TB data per night,...
We present RAPID (Real-time Automated Photometric IDentification), a novel time-series classification tool capable of automatically identifying transients from within day the initial alert, to full lifetime light curve. Using deep recurrent neural network with Gated Recurrent Units (GRUs), we first method specifically designed provide early classifications astronomical data, typing 12 different transient classes. Our classifier can process curves any phase coverage, and it does not rely on...
We present the cosmological analysis of 752 photometrically-classified Type Ia Supernovae (SNe Ia) obtained from full Sloan Digital Sky Survey II (SDSS-II) Supernova (SN) Survey, supplemented with host-galaxy spectroscopy SDSS-III Baryon Oscillation Spectroscopic (BOSS). Our photometric-classification method is based on SN typing technique Sako et al. (2011), aided by host galaxy redshifts (0.05<z<0.55). SNANA simulations our methodology estimate that we have a efficiency 70.8%, only 3.9%...
The Zwicky Transient Facility is a large optical survey in multiple filters producing hundreds of thousands transient alerts per night. We describe here various machine learning (ML) implementations and plans to make the maximal use data set by taking advantage temporal nature data, further combining it with other sets. start initial steps separating bogus candidates from real ones, stars galaxies, go on classification objects into classes. Besides usual methods (e.g., based features...
Abstract We describe the simulated sky survey underlying second data challenge (DC2) carried out in preparation for analysis of Vera C. Rubin Observatory Legacy Survey Space and Time (LSST) by LSST Dark Energy Science Collaboration (LSST DESC). Significant connections across multiple science domains will be a hallmark LSST; DC2 program represents unique modeling effort that stresses this interconnectivity way has not been attempted before. This encompasses full end-to-end approach: starting...
Abstract Next-generation surveys like the Legacy Survey of Space and Time (LSST) on Vera C. Rubin Observatory (Rubin) will generate orders magnitude more discoveries transients variable stars than previous surveys. To prepare for this data deluge, we developed Photometric LSST Astronomical Time-series Classification Challenge (PLAsTiCC), a competition that aimed to catalyze development robust classifiers under LSST-like conditions nonrepresentative training set large photometric test...
ABSTRACT Strongly lensed supernovae are rare and valuable probes of cosmology astrophysics. Upcoming wide-field time-domain surveys, such as the Vera C. Rubin Observatory’s Legacy Survey Space Time (LSST), expected to discover an order-of-magnitude more than have previously been observed. In this work, we investigate cosmological prospects type Ia (SNIa) in LSST by quantifying annual number detections, impact stellar microlensing, follow-up feasibility, how best separate unlensed SNIa. We...
Ground and space-based sky surveys enable powerful cosmological probes based on measurements of galaxy properties the distribution galaxies in Universe. These include weak lensing, baryon acoustic oscillations, abundance clusters, redshift space distortions; they are essential to improving our knowledge nature dark energy. On theory modeling front, large-scale simulations cosmic structure formation play an important role interpreting observations challenging task extracting physics at needed...
Abstract The Vera Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to process ∼10 6 transient detections per night. For precision measurements cosmological parameters rates, it critical understand the detection efficiency, magnitude limits, artifact contamination levels, biases in selection photometry. Here we rigorously test LSST Difference Image Analysis (DIA) pipeline using simulated images from Dark Energy Science Collaboration Data Challenge (DC2) simulation for...
The third observing run by LVC has brought the discovery of many compact binary coalescences. Following detection first neutron star merger in this (LIGO/Virgo S190425z), we performed a dedicated follow-up campaign with Zwicky Transient Facility (ZTF) and Palomar Gattini-IR telescopes. initial skymap single-detector gravitational wave (GW) trigger spanned most sky observable from Observatory. Covering 8000 deg$^2$ over next two nights, corresponding to 46\% integrated probability, ZTF system...
We describe the simulated data sample for "Photometric LSST Astronomical Time Series Classification Challenge" (PLAsTiCC), a publicly available challenge to classify transient and variable events that will be observed by Large Synoptic Survey Telescope (LSST), new facility expected start in early 2020s. The was hosted Kaggle, ran from 2018 September 28 December 17, included 1,094 teams competing prizes. Here we provide details of 18 source models, which were not revealed until after...
ABSTRACT We present the goals, strategy, and first results of high-cadence Galactic plane survey using Zwicky Transient Facility (ZTF). The goal is to unveil population short-period variable stars, including binaries, stellar pulsators with periods less than a few hours. Between 2018 June 2019 January, we observed 64 ZTF fields resulting in 2990 deg2 high density ZTF-r band along plane. Each field was continuously for 1.5 6 h cadence 40 sec. Most have between 200 400 observations obtained...
A BSTRACT Context: Patient satisfaction is a crucial indicator of service quality in the healthcare system. There limited information regarding level sexual minority groups people living with HIV (PLHIV) treatment services. Aims: This comparative study assessed client among general (male and female) patients group antiretroviral delivery at ART center. Settings Design: cross-sectional analytical mixed-method approach was conducted from September 2023 to May 2024 center Barasat Government...
Following Kamionkowski (2008), a quadratic estimator of the rotation plane polarization cosmic microwave background (CMB) is constructed. This statistic can estimate spatially varying angle $\ensuremath{\alpha}(n)$. We use this to quantify prospects detecting such field with forthcoming experiments. For PLANCK and CMBPol experiments, we find that containing product $E$ $B$ components most sensitive. The variance $EB$ $N(L)$ roughly independent multipole $L$ only weakly dependent on...
The Akaike information criterion (AIC) has been used as a statistical to compare the appropriateness of different dark energy candidate models underlying particular data set. Under suitable conditions, AIC is an indirect estimate Kullback-Leibler divergence D(T//A) model A with respect truth T. Thus, smaller ranked better model, since it discrepancy In this paper, we explore impact errors in estimating during comparison. Using parametric bootstrap technique, study distribution differences...