15
15
Jun 27, 2018
06/18
by
Avinash Surendran; Mahesh P. Burse; A. N. Ramaprakash; Padmakar Parihar
texts
eye 15
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The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an Adaptive Optics (AO) system, the generation of the Deformable Mirror (DM) control voltages from the Wavefront Sensor (WFS) measurements is usually through the multiplication of the wavefront slopes with a predetermined reconstructor matrix. The ability to access...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1504.04168
100
100
Jul 20, 2013
07/13
by
Archana Soam; G. Maheswar; H. C. Bhatt; Chang Won Lee; A. N. Ramaprakash
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eye 100
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We present results of our $R-$band polarimetry of a cometary globule, LBN 437 (Gal96-15, $\ell$ $=$ 96$\degree$, \textit{b} $=-15\degree$), to study magnetic field geometry of the cloud. We estimated a distance of $360\pm65$ pc to LBN 437 (also one additional cloud, CB 238) using near-IR photometric method. Foreground contribution to the observed polarisation values was subtracted by making polarimetric observations of stars that are located in the direction of the cloud and with known...
Source: http://arxiv.org/abs/1304.1618v1
75
75
Sep 23, 2013
09/13
by
Mudit K. Srivastava; A. N. Ramaprakash; Mahesh P. Burse; Pravin A. Chordia; Kalpesh S. Chillal; Vilas B. Mestry; Hillol K. Das; Abhay A. Kohok
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eye 75
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Although the astronomy community is witnessing an era of large telescopes, smaller and medium sized telescopes still maintain their utility being larger in numbers. In order to obtain better scientific outputs it is necessary to incorporate modern and advanced technologies to the back-end instruments and to their interfaces with the telescopes through various control processes. However often tight financial constraints on the smaller and medium size observatories limit the scope and utility of...
Source: http://arxiv.org/abs/0904.3162v1
5
5.0
Jun 30, 2018
06/18
by
Christoph Baranec; Reed Riddle; Nicholas M. Law; A. N. Ramaprakash; Shriharsh Tendulkar; Kristina Hogstrom; Khanh Bui; Mahesh Burse; Pravin Chordia; Hillol Das; Richard Dekany; Shrinivas Kulkarni; Sujit Punnadi
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eye 5
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As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limits their availability for following up large numbers of targets. To address this need, we have engineered and...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1407.8179
61
61
Sep 21, 2013
09/13
by
Reed L. Riddle; Mahesh P. Burse; Nicholas M. Law; Shriharsh P. Tendulkar; Christoph Baranec; Alexander R. Rudy; Marland Sitt; Ankit Arya; Athanasios Papadopoulos; A. N. Ramaprakash; Richard G. Dekany
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Robo-AO is the first astronomical laser guide star adaptive optics (AO) system designed to operate completely independent of human supervision. A single computer commands the AO system, the laser guide star, visible and near-infrared science cameras (which double as tip-tip sensors), the telescope, and other instrument functions. Autonomous startup and shutdown sequences as well as concatenated visible observations were demonstrated in late 2011. The fully robotic software is currently...
Source: http://arxiv.org/abs/1301.6790v1
41
41
Sep 20, 2013
09/13
by
M. G. Hidas; Y. Tsapras; R. A. Street; A. N. Ramaprakash; D. Mislis; J. H. M. M Schmitt; I. Steele; S. C. C. Barros; D. Pollacco; A. Ayiomamitis; J. Antoniadis; A. Nitsos; J. H. Seiradakis; S. Urakawa
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eye 41
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We have used four telescopes at different longitudes to obtain near-continuous lightcurve coverage of the star HD 80606 as it was transited by its \sim 4-MJup planet. The observations were performed during the predicted transit windows around the 25th of October 2008 and the 14th of February 2009. Our data set is unique in that it simultaneously constrains the duration of the transit and the planet's period. Our Markov-Chain Monte Carlo analysis of the light curves, combined with constraints...
Source: http://arxiv.org/abs/1002.1052v2
5
5.0
Jun 30, 2018
06/18
by
Reed L. Riddle; Andrei Tokovinin; Brian D. Mason; William I. Hartkopf; Lewis C. Roberts,; Christoph Baranec; Nicholas M. Law; Khanh Bui; Mahesh P. Burse; H. K. Das; Richard G. Dekany; Shrinivas Kulkarni; Sujit Punnadi; A. N. Ramaprakash; Shriharsh P. Tendulkar
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eye 5
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We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the SDSS $i'$ band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with...
Topics: Instrumentation and Methods for Astrophysics, Astrophysics, Solar and Stellar Astrophysics
Source: http://arxiv.org/abs/1411.0682
43
43
Sep 22, 2013
09/13
by
S. C. Odewahn; S. G. Djorgovski; S. R. Kulkarni; M. Dickinson; D. A. Frail; A. N. Ramaprakash; J. S. Bloom; K. L. Adelberger; J. Halpern; D. J. Helfand; J. Bahcall; R. Goodrich; F. Frontera; M. Feroci; L. Piro; E. Costa
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eye 43
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We report on Hubble Space Telescope (HST) observations of the host galaxy of GRB 971214, about four months after the burst. The redshift of the proposed host galaxy at z=3.418, combined with optical and radio observations of the burst afterglow, implies the extremely large isotropic energy release from the burst in gamma-rays of approximately 3x10^53 ergs, some two orders of magnitude higher than the previously commonly assumed numbers. The positional offset between the optical transient...
Source: http://arxiv.org/abs/astro-ph/9807212v3
53
53
Sep 22, 2013
09/13
by
Emil Terziev; Nicholas M. Law; Iair Arcavi; Christoph Baranec; Joshua S. Bloom; Khanh Bui; Mahesh P. Burse; Pravin Chorida; H. K. Das; Richard G. Dekany; Adam L. Kraus; S. R. Kulkarni; Peter Nugent; Eran O. Ofek; Sujit Punnadi; A. N. Ramaprakash; Reed Riddle; Shriharsh P. Tendulkar
texts
eye 53
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The direct detection of binary systems in wide-field surveys is limited by the size of the stars' point-spread-functions (PSFs). A search for elongated objects can find closer companions, but is limited by the precision to which the PSF shape can be calibrated for individual stars. We have developed the BinaryFinder algorithm to search for close binaries by using precision measurements of PSF ellipticity across wide-field survey images. We show that the algorithm is capable of reliably...
Source: http://arxiv.org/abs/1210.4550v1
7
7.0
Jun 30, 2018
06/18
by
O. G. King; D. Blinov; D. Giannios; I. Papadakis; E. Angelakis; M. Balokovic; L. Fuhrmann; T. Hovatta; P. Khodade; S. Kiehlmann; N. Kylafis; A. Kus; I. Myserlis; D. Modi; G. Panopoulou; I. Papamastorakis; V. Pavlidou; B. Pazderska; E. Pazderski; T. J. Pearson; C. Rajarshi; A. N. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; J. A. Zensus
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eye 7
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We report the polarized optical light curve of a gamma-ray burst afterglow obtained using the RoboPol instrument. Observations began 655 seconds after the initial burst of gamma-rays from GRB131030A, and continued uninterrupted for 2 hours. The afterglow displayed a low, constant fractional linear polarization of $p = (2.1 \pm 1.6)\,\%$ throughout, which is similar to the interstellar polarization measured on nearby stars. The optical brightness decay is consistent with a forward-shock...
Topics: High Energy Astrophysical Phenomena, Astrophysics
Source: http://arxiv.org/abs/1409.2417
88
88
Jul 20, 2013
07/13
by
Philip S. Muirhead; Andrew Vanderburg; Avi Shporer; Juliette Becker; Jonathan J. Swift; James P. Lloyd; Jim Fuller; Ming Zhao; Sasha Hinkley; J. Sebastian Pineda; Michael Bottom; Andrew W. Howard; Kaspar von Braun; Tabetha S. Boyajian; Nicholas Law; Christoph Baranec; Reed Riddle; A. N. Ramaprakash; Shriharsh P. Tendulkar; Khanh Bui; Mahesh Burse; Pravin Chordia; Hillol Das; Richard Dekany; Sujit Punnadi; John Asher Johnson
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eye 88
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We report that Kepler Object of Interest 256 (KOI-256) is a mutually eclipsing post-common envelope binary (ePCEB), consisting of a cool white dwarf (M = 0.592 +/- 0.089 MSun, R = 0.01345 +/- 0.00091 RSun, Teff = 7100 +/- 700 K) and an active M3 dwarf (M = 0.51 +/- 0.16 MSun, R = 0.540 +/- 0.014 RSun, Teff = 3450 +/- 50 K) with an orbital period of 1.37865 +/- 0.00001 days. KOI-256 is listed as hosting a transiting planet-candidate by Borucki et al. and Batalha et al.; here we report that the...
Source: http://arxiv.org/abs/1304.1165v1
4
4.0
Jun 29, 2018
06/18
by
E. Angelakis; T. Hovatta; D. Blinov; V. Pavlidou; S. Kiehlmann; I. Myserlis; M. Boettcher; P. Mao; G. V. Panopoulou; I. Liodakis; O. G. King; M. Balokovic; A. Kus; N. Kylafis; A. Mahabal; A. Marecki; E. Paleologou; I. Papadakis; I. Papamastorakis; E. Pazderski; T. J. Pearson; S. Prabhudesai; A. N. Ramaprakash; A. C. S. Readhead; P. Reig; K. Tassis; M. Urry; J. A. Zensus
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eye 4
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We present average R-band optopolarimetric data, as well as variability parameters, from the first and second RoboPol observing season. We investigate whether gamma- ray--loud and gamma-ray--quiet blazars exhibit systematic differences in their optical polarization properties. We find that gamma-ray--loud blazars have a systematically higher polarization fraction (0.092) than gamma-ray--quiet blazars (0.031), with the hypothesis of the two samples being drawn from the same distribution of...
Topics: Astrophysics, High Energy Astrophysical Phenomena, Cosmology and Nongalactic Astrophysics
Source: http://arxiv.org/abs/1609.00640
38
38
Sep 24, 2013
09/13
by
Nicholas M. Law; Adam L. Kraus; Rachel Street; Benjamin J. Fulton; Lynne A. Hillenbrand; Avi Shporer; Tim Lister; Christoph Baranec; Joshua S. Bloom; Khanh Bui; Mahesh P. Burse; S. Bradley Cenko; H. K. Das; Jack. T. C. Davis; Richard G. Dekany; Alexei V. Filippenko; Mansi M. Kasliwal; S. R. Kulkarni; Peter Nugent; Eran O. Ofek; Dovi Poznanski; Robert M. Quimby; A. N. Ramaprakash; Reed Riddle; Jeffrey M. Silverman; Suresh Sivanandam; Shriharsh Tendulkar
texts
eye 38
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We present three new eclipsing white-dwarf / M-dwarf binary systems discovered during a search for transiting planets around M-dwarfs. Unlike most known eclipsing systems of this type, the optical and infrared emission is dominated by the M-dwarf components, and the systems have optical colors and discovery light curves consistent with being Jupiter-radius transiting planets around early M-dwarfs. We detail the PTF/M-dwarf transiting planet survey, part of the Palomar Transient Factory (PTF)....
Source: http://arxiv.org/abs/1112.1701v1
11
11
Jun 26, 2018
06/18
by
Lewis C. Roberts,; Brian D. Mason; Christopher R. Neyman; Yanqin Wu; Reed L. Riddle; J. Christopher Shelton; John Angione; Christoph Baranec; Antonin Bouchez; Khanh Bui; Rick Burruss; Mahesh Burse; Pravin Chordia; Ernest Croner; Hillol Das; Richard G. Dekany; Stephen Guiwits; David Hale; John Henning; Shrinivas Kulkarni Nicholas Law; Dan McKenna; Jennifer Milburn; Dean Palmer; Sujit Punnadi; A. N. Ramaprakash; Jennifer E. Roberts; Shriharsh P. Tendulkar; Thang Trinh; Mitchell Troy; Tuan Truong;...
texts
eye 11
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HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identified a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of filters with the aim of confirming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a...
Topics: Solar and Stellar Astrophysics, Astrophysics
Source: http://arxiv.org/abs/1502.06630
