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Browsing by Author "Sagar, R"

Browsing by Author "Sagar, R"

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  • The 3.6 metre Devasthal optical telescope: from inception to realization 
    Sagar, R; Kumar, Brijesh; Omar, A (Indian Academy of Sciences, 2019-08-10)
    India’s largest 3.6 metre Devasthal Optical Telescope (DOT) was commissioned in 2016, though the idea of building it germinated way back in 1976. This article provides research accounts as well as glimpses of its nearly ...
  • 3.6-m Devasthal Optical Telescope Project: Completion and first results 
    Kumar, Brijesh; Omar, A; Maheswar, G; Pandey, A. K; Sagar, R; Uddin, W; Sanwal, B. B; Bangia, T; Kumar, T. S; Yadav, S; Sahu, S; Pant, J; Reddy, B. K; Gupta, A. C; Chand, H; Pandey, J. C; Joshi, M. K; Jaiswar, M; Nanjappa, N; Purushottam; Yadav, R. K. S; Sharma, S; Pandey, S. B; Joshi, S; Joshi, Y. C; Lata, S; Mehdi, B. J; Misra, K; Singh, M (Societe Royale des Sciences de Liege, 2018-04)
    We present an update on the 3.6-m aperture optical telescope, which has been installed at Devasthal in the year 2016. In this paper, a brief overview of installation activities at site and first results are presented. The ...
  • The 4-m International Liquid Mirror Telescope 
    Surdej, J; Hickson, P; Borra, E; Swings, J; Habraken, S; Akhunov, T; Bartczak, P; Chand, H; De Becker, M; Delchambre, L; Finet, F; Kumar, B; Pandey, A; Pospieszalska, A; Pradhan, B; Sagar, R; Wertz, O; De Cat, P; Denis, S; de Ville, J; Jaiswar, M. K; Lampens, P; Nanjappa, N; Tortolani, J (Societe Royale des Sciences de Liege, 2018-04)
    The 4-m International Liquid Mirror Telescope (ILMT) is presently (March-June 2017) being erected on the ARIES site in Devasthal (Uttarakhand). We describe and illustrate in the present paper its different components. ...
  • An Analysis of Proper Motion and Membership Probability in Open Clusters 
    Sagar, R (Astronomical Society of Indian, 1987-12)
    An analysis of the proper motion data and membership probability has been carried out for nine open clusters. The effects of observational errors on the parameters characterzing the frequency distributions of cluster and ...
  • ARIES, Nainital: a strategically important location for climate change studies in the Central Gangetic Himalayan region 
    Sagar, R; Dumka, U. C; Naja, M; Singh, N; Phanikumar, D. V (Indian Academy of Sciences, 2015-08-25)
    ARIES, acronym for Aryabhatta Research Institute of Observational Sciences, located in the Central Gangetic Himalayan (CGH) region is emerging as one of the unique sites for climate change studies. The long-term, in situ, ...
  • Atmospheric extinction at Devasthal, Naini Tal 
    Mohan, V; Uddin, W; Sagar, R; Gupta, S. K (Astronomical Society of India, 1999)
    The atmospheric extinction coefficients in Johnson U, B, V, R and I photometric passbands are determined for the first time at Devasthal, Naini Tal during 1998 and 1999. A solid state stellar photometer mounted on a 52-cm ...
  • Binary star clusters in galaxies : Our galaxy 
    Subramaniam, A; Gorti, U; Sagar, R; Bhatt, H. C (Astronomical Society of India, 2000)
  • BVRI CCD photometric standards in the field of GRB 990123 
    Nilakshi; Yadav, R. K. S; Mohan, V; Pandey, A. K; Sagar, R (Astronomical Society of India, 1999)
    The CCD magnitudes in Johnson BV and Cousins RI photometric passbands are determined for 18 stars in the field of GRB 990123. These mesurements can be used in carrying out precise CCD photometry of the optical transient ...
  • CCD imaging of gamma ray burster fields 
    Bhargavi, S. G; Cowsik, R; Pati, A. K; Sagar, R (Astronomical Society of India, 1998)
  • CCD photometry in VRI bands of the galactic cluster NGC 2818 
    Surendiranath, R; Kameswara Rao, N; Sagar, R; Nathan, J. S; Ghosh, K. K (Indian Academy of Sciences, 1990-06)
    The open cluster NGC 2818 containing a planetary nebula has been observed in VRI bands using the CCD system at prime focus of the 2.3 meter Vainu Bappu Telescope. The study extending to stars V of 21 magnitude established ...
  • CCD Photometry of NGC 2453 
    Mallik, D. C. V; Sagar, R; Pati, A. K (International Astronomical Union, 1993)
  • CCD photometry of the distant southern globular cluster NGC 5824 
    Cannon, R. D; Sagar, R; Hawkins, M. R. S (Royal Astronomical Society, 1990-03)
    A V, (B-V) C-M diagram for the distant globular cluster NGC 5824 is obtained from CCD observations of 285 stars reaching V = 20.5. Assuming a reddening of E(B-V) = 0.13, the color of the giant branch at the level of the ...
  • CCD photometry of the distant young open cluster NGC 7510 
    Sagar, R; Griffiths, W. K (Royal Astronomical Society, 1991-06)
    CCD observations in B, V, and I passbands have been used to generate deep V, (B-V), and V,(V-I) color-magnitude diagrams for the open cluster NGC 7510. The sample consists of 592 stars reaching down to V = 21 mag. There ...
  • CCD photometry of the galactic open star clusters. I - King 10 
    Mohan, V; Pandey, A. K; Paliwal, D. C; Sagar, R; Mahra, H. S (Astronomical Society of India, 1992)
    CCD photometry of the open cluster King 10 has been carried out in the UBVRI photometric passbands down to V of about 19.5 mag. The reddening for the cluster region is found to be variable. A distance of 3.2 kpc has been ...
  • CCD photometry of the galactic star clusters Be 15, Be 71 and King 1 
    Lata, S; Mohan, V; Sagar, R (Astronomical Society of India, 2004-12)
    We present UBV RI CCD photometry of three open star clusters Be 15, Be 71 and King 1 for the fist time. Base on these data, optical colour magnitude diagrams (CMDs) for the stars in the clusters down to V = 22 mag are ...
  • CCD photometry of the unstudied galactic star clusters Be 10, Be 67 and To 5 
    Lata, S; Mohan, V; Pandey, A. K; Sagar, R (Astronomical Society of India, 2004-03)
    We present the broad band Johnson U BV and Cousins RI CCD photometric observations for open clusters Be 10, Be 67 and To 5. So far no photometric study of these clusters is published. The colour-magnitude diagrams indicate ...
  • Changing look AGN Mrk 590: broad-line region and black hole mass from photometric reverberation mapping 
    Amit Kumar Mandal; Schramm, Malte; Rakshit, Suvendu; Stalin, C. S; Vijarnwannaluk, Bovornpratch; Rujopakarn, Wiphu; Poshyachinda, Saran; Kouprianov, Vladimir V; Haislip, Joshua B; Reichar, Daniel E; Sagar, R; Mathew, Blesson (Oxford University Press on behalf of Royal Astronomical Society, 2021-12)
    We present the results of photometric reverberation mapping observations on the changing look active galactic nucleus Mrk 590 at z = 0.026. The observations were carried out from 2018 July to December using broad-band B-, ...
  • A comparative study of the intra-night optical variability of powerful AGNs 
    Stalin, C. S; Gopal-Krishna; Sagar, R; Wiita, P. J (Astronomical Society of India, 2002-09)
    In order to address a currently much debated issue, we are carrying out a systematic search for intra-night optical micro-variability in major classes of powerful (M'II ~ -23.0 mag) active galactic nuclei (AGNs). Our ...
  • A complete photometric study of the open cluster NGC 7790 containing Cepheid variables 
    Gupta, A. C; Subramaniam, A; Sagar, R; Griffiths, W. K (EDP Sciences, 2000-09)
    CCD photometry of the northern open star cluster NGC 7790 has been carried out in BVI photometric passbands down to V ~ 21 mag for 1150 stars of which for ~ 700 stars, the data is obtained for the first time. We derive the ...
  • Comprehensive multiwavelength modelling of the afterglow of GRB 050525A 
    Resmi, L; Misra, K; Johannesson, G; Castro-Tirado, A. J; Gorosabel, J; Jelınek, M; Bhattacharya, D; Kubanek, P; Anupama, G. C; Sota, A; Sahu, D. K; de Ugarte Postigo, A; Pandey, S. B; Sanchez-Ramırez, R; Bremer, M; Sagar, R (Wiley-Blackwell, 2012-11)
    The Swift era has posed a challenge to the standard blast-wave model of gamma-ray burst (GRB) afterglows. The key observational features expected within the model are rarely observed, such as the achromatic steepening ...

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