Refine your search
Collections
Journals
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Bhattacharya, D.
- Cadmium-Zinc-Telluride Imager On-Board Astrosat:A Multi-Faceted Hard X-Ray Instrument
Abstract Views :233 |
PDF Views:87
Authors
Affiliations
1 Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IN
2 Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, IN
3 Physical Research Laboratory, Ahmedabad 380 009, IN
4 Vikram Sarabhai Space Centre, Thiruvananthapuram 695 024, IN
1 Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IN
2 Inter-University Centre for Astronomy and Astrophysics, Pune 411 007, IN
3 Physical Research Laboratory, Ahmedabad 380 009, IN
4 Vikram Sarabhai Space Centre, Thiruvananthapuram 695 024, IN
Source
Current Science, Vol 113, No 04 (2017), Pagination: 595-598Abstract
The AstroSat satellite is designed to make multi-waveband observations of astronomical sources and the Cadmium-Zinc-Telluride Imager (CZTI) instrument of AstroSat covers the hard X-ray band. CZTI has a large area position-sensitive hard X-ray detector equipped with a coded aperture mask, thus enabling simultaneous background measurements. Ability to record simultaneous detection of ionizing interactions in multiple detector elements is a special feature of the instrument, and this is exploited to provide polarization information in the 100-380 keV region. CZTI provides sensitive spectroscopic measurements in the 20-100 keV region, and acts as an all-sky hard X-ray monitor and polarimeter above 100 keV. During the first year of operation, CZTI has recorded several gamma-ray bursts, measured the phase-resolved hard X-ray polarization of the Crab pulsar, and the hard X-ray spectra of many bright galactic X-ray binaries. The excellent timing capability of the instrument has been demonstrated with simultaneous observation of the Crab pulsar with radio telescopes like Gaint Metrewave Radio Telescope and Ooty Radio Telescope.Keywords
All-Sky Hard X-Ray Monitor, Gamma-Ray Bursts, Neutron Stars, X-Ray Polarization.Full Text
References
- Singh, K. P. et al., AstroSat mission. In Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series: Space Telescopes and Instrumentation 2014: UV to Gamma Ray, at Montreal, 2014, vol. 9144, 91441S (p. 15).
- Bhalerao, V. et al., The Cadmium–Zinc–Telluride Imager on AstroSat. JAA, 2017, 38, 31.
- Bhalerao, V., Bhattacharya, D., Rao, A. R. and Vadawale, S., GRB151006A: AstroSat CZTI detection. GRB Coordinates Network, 2015, 18422, 1.
- Rao, A. R. et al., AstroSat CZT Imager observations of GRB151006A: timing, spectroscopy, and polarization study. ApJ, 2016, 833, 86.
- Bhalerao, V. et al., LIGO/Virgo G211117: AstroSat CZTI upper limits. GRB Coordinates Network, 2016, 19401, 1.
- Bhalerao, V., Bhattacharya, D., Rao, A. R. and Vadawale, S., GRB170105A: AstroSat CZTI localisation. GRB Coordinates Network, 2016, 20412, 1.
- Chattopadhyay, T., Vadawale, S. V., Rao, A. R., Sreekumar, S., and Bhattacharya, D., Prospects of hard X-ray polarimetry with AstroSat–CZTI. Exp. Astron., 2014, 37, 555.
- Vadawale, S. V. et al., Hard X-ray polarimetry with AstroSat–CZTI. Astron. Astrophys., 2015, 578, A73.
- Buhler, R. and Blandford, R., The surprising Crab pulsar and its nebula: a review. Rep. Prog. Phys., 2014, 77(6), 066901.
- Lyne, A. G., Pritchard, R. S. and Graham-Smith, F., Twenty-three years of Crab pulsar rotational history. MNRAS, 1993, 265, 1003.
- Multi-Colour Hues of the Universe Observed with AstroSat
Abstract Views :219 |
PDF Views:81
Authors
Affiliations
1 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IN
2 Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007, IN
1 Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400 005, IN
2 Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007, IN
Source
Current Science, Vol 113, No 04 (2017), Pagination: 602-609Abstract
India's space astronomy observatory AstroSat was launched on 28 September 2015, carrying instruments to observe cosmic sources over a large spectral band, from optical/UV to hard X-rays. The mission, with all its payloads, has been operating successfully since its launch. After an initial period of performance verification and calibration, the satellite is now in full science operation. This article gives a brief introduction about the capabilities of the mission and presents some of the early science results.Keywords
Active Galaxies, Cosmic Sources, Multi-Wavelength Astronomy, Multi-Colour Hues, Supernova Remnants.Full Text
References
- Singh, K. P. et al., ASTROSAT mission. In Proceedings of SPIE, Space Telescopes and Instrumentation 2014: UV to Gamma Ray (eds Takahashi, T., den Herder, J.-W. A. and Bautz, M.), 2014, vol. 9144, pp. 91441S-1 to S-15 Montreal; doi: 10.1117/12.2062667.
- Bhalerao, V. et al., The cadmium zinc telluride imager on AstroSat. JApA, 2017, 38, 31–40.
- Ramadevi, M. C. et al., Early in-orbit performance of scanning sky monitor onboard AstroSat. J. Astrophys. Astr, 2017, 38, 32–34.
- Singh, K. P. et al., In-orbit performance of SXT aboard AstroSat. In Proceedings of SPIE, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray (eds den Herder, J.-W. A., Takahashi, T. and Bautz, M.), 2016, vol. 9905, pp. 99051E-1 to E-10; doi:10.1117/12.2235309.
- Singh, K. P. et al., Soft X-ray focusing telescope aboard AstroSat: design, characteristics and performance. J. Astrophys. Astr., 2017, 38, 29.
- Subramaniam, A. et al., In-orbit performance of UVIT on ASTROSAT. In Proceedings of SPIE, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray (eds den Herder, J.-W. A., Takahashi, T. and Bautz, M.), 2016, vol. 9905, pp. 99051F-1 to F-10; doi:10.1117/12.2235271 (arxiv: 1608.01073).
- Tandon, S. N. et al., In-orbit performance of UVIT and first results. J. Astophys. Astr., 2017, 38, 28.
- Vadawale, S. V. et al., In-orbit performance AstroSat CZTI. In Proceedings of SPIE, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray (eds den Herder, J.-W. A., Takahashi, T. and Bautz, M.), 2016, vol. 9905, pp. 99051G-1 to G-11.
- Yadav, J. S. et al., In Proceedings of SPIE Space Telescopes and Instrumentation 2016a: Ultraviolet to Gamma Ray (eds den Herder, J.-W. A., Takahashi, T. and Bautz, M.), 2016, vol. 9905, pp. 99051D; doi:10.1117/12.2231857.
- Subramaniam, A. et al., A hot companion to a blue straggler in NGC 188 as revealed by the ultra-violet imaging telescope (UVIT) on AstroSat. ApJL, 2016, 833, L27–L31.
- Tandon, S. N., Ghosh, S. K., Hutchings, J., Stalin, S. and Subramaniam, A., Ultraviolet Imaging Telescope (UVIT) on AstroSat. Curr. Sci., 2017, 113(4), 583–586.
- Chattopadhyay, T., Vadawale, S. V., Rao, A. R., Sreekumar, S. and Bhattacharya, D., Prospects of hard X-ray polarimetry with Astrosat-CZTI. Experiment. Astr., 2014, 37, 555–577.
- Rao, A. R. et al., AstroSat CZT imager observations of GRB 151006A: timing, spectroscopy, and polarization study. ApJ, 2016, 833, 86–95.
- Yadav, J. S. et al., AstroSat/LAXPC reveals the high-energy variability of GRS 1915+105 in the X class. ApJ, 2016, 833, 27–35.
- Misra, R. et al., AstroSat/LAXPC observation of Cygnus X-1 in the hard state. ApJ, 2017, 835, 195–200.
- Singh, K. P., Dewangan, G. C., Chandra, S., Bhattacharayya, S., Chitnis, V., Stewart, G. C. and Westergaard, N. J., Soft X-ray focusing telescope aboard AstroSat: early results. Curr. Sci., 2017, 113(4), 587–590.
- Buhler, R. and Blandford, R., The surprising Crab pulsar and its nebula: a review. Rep. Prog. Phys., 2014, 77, 066901 (pp. 15).
- Fabian, A. C., Willingale, R., Pye, J. P., Murray, S. S. and Fabianno, G., The X-ray structure and mass of the Cassiopeia A supernova remnant. MNRAS, 1980, 193, 175–188.
- Favata, F. et al., The broad-band X-ray spectrum of the CAS A supernova remnant as seen by the BeppoSAX observatory. A&A, 1997, 324, L49–L52.
- Fesen, R. A., Kwitter, K. B. and Downes, R. A., H-alpha images of the Cygnus Loop – a new look at shock-wave dynamics in an old supernova remnant. AJ, 1992, 104, 719–724.
- Levenson, N. A., Graham, J. R. and Snowden, S. L., The Cygnus loop: a soft-shelled supernova remnant. ApJ, 1999, 526, 874–880.
- Unusually High Frequency of Cross-Pollination Between Rice Landraces Shiuli and Kharah with Coincident Flower-Opening Times
Abstract Views :208 |
PDF Views:89
Authors
Debal Deb
1,
D. Bhattacharya
1
Affiliations
1 Centre for Interdisciplinary Studies, 186A Kalikapur Canal Road, Kolkata 700 099, IN
1 Centre for Interdisciplinary Studies, 186A Kalikapur Canal Road, Kolkata 700 099, IN
Source
Current Science, Vol 121, No 1 (2021), Pagination: 121-126Abstract
Cross-pollination in cultivated rice (Oryza sativa L.) is rarely reported to exceed 2%. This low cross-pollination frequency (CPF) is conducive to success-fully maintaining the purity of rice landraces for many generations. We were therefore surprised to notice a dramatic loss of genetic purity in some of the pure line landraces in many farmers’ fields. Having ruled out the possibility of mixing of seeds from dif-ferent varieties, we surmised this rapid loss of genetic purity to be due to a somewhat higher degree of cross-pollination, and conducted a carefully designed expe-riment with suitably chosen pairs of landraces. We report here an unusually high (>81%) CPF seen in a pair of landraces whose flower opening times (FOTs) were coincident. Our control experiment on a pair of landraces with non-overlapping FOTs failed to detect any cross-pollination. This preliminary report sug-gests that the crucial importance of FOT diversity in landraces in determining CPF has not been recognized in designs of previous reports of crossing experiments, resulting in a severe underestimation of CPF in cultivated rice under natural conditions.Keywords
Cross-Pollination Frequency, Flower Opening and Closing Times, Genetic Purity, Pollen Viability, Rice Landraces.Full Text
References
- Endo, T., Sato, H., Yamaguchi, M., Kataoka, T., Nakagomi, K., Ito, T. and Mori, K., Estimate of outcrossing rates in a rice plant (Oryza sativa L.) under field conditions using a purple grain rice cultivar, Okunomurasiki. Breed. Sci., 2009, 59, 195–202.
- da Silva, E. F., da Silva, L. M. and Montalván, R., Crossing rate and distance in upland rice. Bragantia, 2005, 64(2), 197–201.
- Reaño, R. and Pham, J. L., Does cross-pollination occur during seed regeneration at the International Rice Genebank? Intern. Rice Res. Notes, 1998, 23, 5–6.
- Jodon, N. E., Occurrence and importance of natural crossing in rice. Rice J., 1959, 62(8), 8–10.
- Robert, E. H., Craufurd, R. Q. and Cochet, F. L., Estimation of percentage of natural cross-pollination: experiment on rice. Nature, 1961, 190, 1084–1085.
- Sahadevan, P. C. and Namboodiri, K. M. N., Natural crossing in rice. Proc. Indian Acad. Sci., Sect. B, 1963, 58, 176–185.
- Beachell, H. M., Adair, C. R., Jodon, N. E., Davis, L. L. and Jones, J. W., Extent of natural crossing in rice. J. Am. Soc. Agron, 1938, 30, 743–653.
- Coste, R., El Arroz: Colección Agricultura Tropical, Editorial Blume, Barcelona, Spain, 1969, 2nd edn, pp. 35–72.
- Somaratne, L. H. M. Y. K., Abayawickrama, A. S. M. T., Wickramasinghe, I. P. and Samarasinghe, W. L. G., Estimating outcrossing rate of Bg 379-2 using morphological markers and confirmation by molecular markers. Rice Sci., 2012, 19(2), 166–168.
- Messeguer, J., Fogher, C., Guiderdoni, E., Marfà, V., Català, M. M., Baldi, G. and Melé, E., Field assessments of gene flow from transgenic to cultivated rice Oryza sativa L. using a herbicide resistance gene as tracer marker. Theor. Appl. Genet., 2001, 103, 1151–1159.
- Messeguer, J., Marfà, V., Català, M. M., Guiderdoni, E. and Melé, E. A., Field study of pollen-mediated gene flow from Mediterranean GM rice to conventional rice and the red rice weed. Mol. Breed., 2004, 13, 103–112.
- Rong, J. et al., Dramatic reduction of crop-to-crop gene flow within a short distance from transgenic rice fields. New Phytol., 2007, 173, 346–353.
- Bae, H.-K. et al., Evaluation of gene flow from GM to non-GM rice. Plant Breed. Biotech., 2013, 1(2), 162–170.
- Langevin, S. A., Clay, K. and Grace, J. B., The incidence and effect of hybridization between cultivated rice and its related weed red rice (Oryza sativa L.). Evolution, 1990, 44, 1000–1008.
- Song, Z. P., Lu, B.-R., Zhu, Y. G. and Chen, J. K., Gene flow from cultivated rice to the wild species Oryza rufipogon under experimental field conditions. New Phytol., 2003, 157, 657–665.
- Wang, F. et al., A large-scale field study of transgene flow from cultivated rice (Oryza sativa) to common wild rice (O. rufipogon) and barnyard grass (Echinochloa crus-galli). Plant Biotechnol. J., 2006, 4, 667–676.
- Moldenhauer, K. A. K. and Gibbons, J. H., Rice morphology and development. In Rice: Origin, History, Technology and Production (eds Smith, C. W. and Dilday, R. H.), Wiley, Hoboken, NJ, USA, 2003, pp. 103–127.
- OGTR, The Biology and Ecology of Rice (Oryza sativa L.) in Australia, Office of the Gene Technology Regulator, Woden, Australia, 2005.
- Deb, D., Flowering asynchrony can maintain genetic purity in rice landraces. Curr. Sci., 2006, 91, 155–157.
- GoI, Biology of Oryza sativa L. (Rice), Department of Biotechnology, Ministry of Science and Technology, and Ministry of Environment and Forests, Government of India, 2011; http://biosafety.icar.gov.in/biology-of-oryza-sativa-l-rice
- Kobayasi, K., Masui, H., Atsuta, Y., Matsui, T., Yoshimoto, M. and Hasegawa, T., Flower opening time in rice –cultivar difference and effect of weather factors. In Proceedings of MARCO Symposium 2009: challenges for Agro-Environmental Research in monsoon Asia, (CD-ROM), National Institute for Agro-Environmental Sciences, Tsukuba, Japan, 2009.
- Kobayasi, K., Matsui, T., Yoshimoto, M. and Hasegawa, T., Effects of temperature, solar radiation, and vapor-pressure deficit on flower opening time in rice. Plant Prod. Sci., 2010, 13(1), 21–28.
- Bioversity International, International Rice Res. Institute and the Africa Rice Center. Descriptors for Wild and Cultivated Rice (Oryza spp.) Bioversity International, Rome, Italy, 2007.