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Browsing IIAP Publications by Title

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  • Valence universal multireference coupled cluster calculations of the properties of indium in its ground and excited states 
    Madhulita Das; Chaudhuri, R. K; Chattopadhyay, S; Mahapatra, U. S (IOP Publishing, 2011-03)
    In view of its importance in high precision spectroscopy, the valence universal multireference coupled cluster (VU-MRCC) method with four-component relativistic spinors has been applied to compute ionization potential (IP) ...
  • Validation of estimated cloud fraction from MERRA-2 and AIRS data using ground based observation over IAO, Hanle 
    Shantikumar, S. N; Narendra, A; Bhatt, B. C; Prabhu, T. P; Anupama, G. C; Angchuk, D; Jorphail, S (Elsevier B.V, 2020-08-15)
    We report for validation of cloud fraction estimated from high-resolution (hourly) data from MERRA-2 and AIRS instrument aboard NASA’s Aqua satellite during its ascending and descending orbits with hourly ground-based ...
  • Validation of water vapor retrieval from Moderate Resolution Imaging Spectro-radiometer (MODIS) in near infrared channels using GPS data over IAO-Hanle, in the trans-Himalayan region 
    Shantikumar, N. S; Jade, S; Shrungeshwara, T. S; Song, H.-J (Elsevier B.V, 2016-01)
    Integrated precipitable water vapor (PWV) retrieved from Moderate Resolution Imaging Spectro-radiometer (MODIS) in near-infrared channels is examined with the PWV estimated from the Global Positioning System (GPS) data and ...
  • Variability and the Size–Luminosity Relation of the Intermediate-mass AGN in NGC 4395 
    Cho, Hojin; Woo, Jong-Hak; Hodges-Kluck, E; Son, Donghoon; Shin, Jaejin; Gallo, Elena; Bae, Hyun-Jin; Brink, T. G; Cho, Wanjin; Filippenko, A. V; Horst, J. C; Ilic, Dragana; Joner, M. D; Kang, Daeun; Kang, Wonseok; Kaspi, Shai; Kim, Taewoo; Kovacevic, A. B; Kumar, S; Le, Huynh Anh N; Nadzhip, A. E; Nunez, F. P; Metlov, V. G; Oknyansky, V. L; Park, Songyoun; Popovic, L. C; Rakshit, S; Schramm, M; Shatsky, N. I; Spencer, M; Sung, E.-H; Sung, H.-i; Tatarnikov, A. M; Vince, O (IOP Publishing, 2020-04-01)
    We present a variability study of the lowest-luminosity Seyfert 1 nucleus of the galaxy NGC 4395 based on photometric monitoring campaigns in 2017 and 2018. Using 22 ground-based and space telescopes, we monitored NGC ...
  • The variability of HD 76536 
    Shylaja, B. S (Kluwer Academic Publishers, 1990-02)
    The spectrophotometric and photometric observations of the WC star HD 76536 are reported. The flux and the magnitude variations appear to be periodic. The possibilities of a compact binary are discussed.
  • Variability of sunspot cycle QBO and total ozone over high altitude Western Himalayan regions 
    Shantikumar, N. S (Elsevier B.V., 2011-10)
    Long-term trend of total column ozone at high altitude region in Ladakh is studied, using a total ozone mapping spectrometer and an ozone monitoring instrument during 1979–2008. In the region, total ozone exhibits seasonality ...
  • Variability of the solar chromospheric network over the solar cycle 
    Kariyappa, R; Sivaraman, K. R (Springer, 1994-06)
    From a large sample of the Kodaikanal spectroheliograms in the Ca II K line we have studied the variations in the intensity of the network elements over two solar cycles and have estimated their contribution to the overall ...
  • Variable circumstellar activity of V351 Orionis 
    Choudhury, R; Bhatt, H. C; Pandey, G (EDP Sciences, 2011-02)
    Context. Emission and absorption line profiles which are formed in the interaction of pre-main sequence stars and their circumstellar environment are found to be variable at various timescales. Aims. We investigate the ...
  • Variable mass accretion and failed wind explain changing-look phenomena in NGC 1365 
    Mondal, Santanu; Adhikari, T. P; Hryniewicz, K; Stalin, C. S; Pandey, Ashwani (EDP Sciences, 2022-06)
    Changing-look active galactic nuclei (CLAGNs) show a complex nature in their X-ray spectral shape and line-of-sight column-density variation. The physical mechanisms responsible for these variations are unclear. Here, we ...
  • THE VARIABLE STAR POPULATION IN THE GLOBULAR CLUSTER NGC 6934 
    Yepez, M. A; Ferro, A. A; Muneer, S; Giridhar, S (Instituto de Astronomia, 2018-04)
    We report an analysis of new V and I CCD time-series photometry of the globular cluster NGC 6934. Through the Fourier decomposition of the RR Lyrae light curves the mean values of [Fe/H] and the distance of the cluster ...
  • Variable stars in M37 
    Dar, A. A; Parihar, P. S; Saleh, P; Malik, M. A (IOP Publishing, 2018-12)
    The CCD photometric observations of open star cluster M37 (NGC 2099) were carried out up to a limiting magnitude of V ~ 20 in both B and V filters to search for variable stars using a 2k × 4k CCD and the 1.3 m telescope ...
  • Variable stars in NGC 4147 revisited: RR Lyrae stars new CCD VI photometry and physical parameters 
    Arellano Ferro, A; Rojas Galindo, F. C; Muneer, S; Giridhar, S (Universidad Nacional Autonoma De Mexico, 2018-10)
    We have calculated the physical parameters of the RR Lyrae stars in the globular cluster NGC 4147 via the Fourier decomposition of their light curves, using new data and well-established semi-empirical calibrations and ...
  • Variable stars in Palomar 13; an evaporating globular cluster 
    Yepez, M. A; Ferro, A. A; Schoeder, K. P; Muneer, S; Giridhar, S; Allen, C (Elsevier B.V, 2019-08)
    We present new CCD VI photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H] = −1.65, and a distance of 23.67 ± ...
  • Variable Stars in Palomar 13; an Evaporating Globular Cluster 
    Yepez, M. A; Ferro, A. Arellano; Schröder, K. P.; Muneer, S; Giridhar, Sunetra; Allen, Christine (Astronomical Society of the Pacific, 2021-06)
    We present new CCD VI photometry of the globular cluster Pal 13. Fourier decomposition of the light curves of RRab stars lead to estimations of [Fe/H]ZW = -1.65±0.15, and a distance to the cluster of 23.67±0.57 kpc. A ...
  • Variable Stars in the Globular Cluster NGC 288: [Fe/H] and Distance 
    Ferro, A. A; Bramich, D.M; Giridhar, S; Jaimes, R. F; Kains, N; Kuppuswamy, K (Copernicus Foundation for Polish Astronomy, 2013-12)
    A search for variable stars in the globular cluster NGC 288 was carried out using a time-series of CCD images in the V and I filters. The photometry of all stellar sources in the field of view of our images, down to V≈19 ...
  • Variable stars in the globular cluster NGC 7492. New discoveries and physical parameter determination 
    Figuera Jaimes, R; Arellano Ferro, A; Bramich, D. M; Giridhar, S; Kuppuswamy, K (EDP Sciences, 2013-08)
    Aims. We have performed a photometric V,R,I CCD time-series analysis with a baseline of about eight years of the outer-halo globular cluster NGC 7492 with the aim of searching for new variables and using these (and the ...
  • A "variable" stellar object in a variable blue nebula V-V 1-7 
    Kameswara Rao, N; Gilra, D. P (The Observatory, 1981-08)
  • Variables in Globular Cluster NGC 5024 
    Safonova, M; Stalin, C. S (IOP Publishing, 2011-12)
    We present the results of a commissioning campaign to observe Galactic globular clusters for the search of microlensing events. The central 10' × 10' region of the globular cluster NGC 5024 was monitored using the 2 m ...
  • The variation in area of hydrogen absorption markings with longitude 
    Salaruddin, M (Government Observatory, Madras, 1932-04-19)
  • Variation in continuum brightness and equivalent widths of lines in sunspot penumbrae 
    Bhatnagar, A (Springer - Verlag, 1966)
    Variations in the continuum brightness and in the equivalent widths of lines have been observed in the sunspot penumbral spectra. Darker regions in the continuum of the penumbrae show widening of lines, while the brighter ...

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