Institute Of Geodynamics Sabba S Stefanescu

Bucharest, Romania

Institute Of Geodynamics Sabba S Stefanescu

Bucharest, Romania
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Vaduvescu O.,Isaac Newton Group of Telescopes ING | Vaduvescu O.,Institute of Astrophysics of Canarias | Birlan M.,IMCCE | Tudorica A.,University of Bonn | And 47 more authors.
Planetary and Space Science | Year: 2013

We report follow-up observations of 477 program Near-Earth Asteroids (NEAs) using nine telescopes of the EURONEAR network having apertures between 0.3 and 4.2 m. Adding these NEAs to our previous results we now count 739 program NEAs followed-up by the EURONEAR network since 2006. The targets were selected using EURONEAR planning tools focusing on high priority objects. Analyzing the resulting orbital improvements suggests astrometric follow-up is most important days to weeks after discovery, with recovery at a new opposition also valuable. Additionally we observed 40 survey fields spanning three nights covering 11 square degrees near opposition, using the Wide Field Camera on the 2.5 m Isaac Newton Telescope (INT), resulting in 104 discovered main belt asteroids (MBAs) and another 626 unknown one-night objects. These fields, plus program NEA fields from the INT and from the wide field MOSAIC II camera on the Blanco 4 m telescope, generated around 12000 observations of 2000 minor planets (mostly MBAs) observed in 34 square degrees. We identify Near Earth Object (NEO) candidates among the unknown (single night) objects using three selection criteria. Testing these criteria on the (known) program NEAs shows that the best selection method is our Ïμ-μ model which checks solar elongation and sky motion and the MPC's NEO rating tool. Our new data show that on average 0.5 NEO candidates per square degree should be observable in a 2 m-class survey (in agreement with past results), while an average of 2.7 NEO candidates per square degree should be observable in a 4 m-class survey (although our Blanco statistics were affected by clouds). At opposition just over 100 MBAs (1.6 unknown to every 1 known) per square degree are detectable to R=22 in a 2 m survey based on the INT data (in accordance with other results), while our two best ecliptic Blanco fields away from opposition lead to 135 MBAs (2 unknown to every 1 known) to R=23. © 2013 Elsevier Ltd.

Vaduvescu O.,Isaac Newton Group of Telescopes | Vaduvescu O.,Institute of Astrophysics of Canarias | Popescu M.,IMCCE | Popescu M.,Polytechnic University of Bucharest | And 17 more authors.
Astronomische Nachrichten | Year: 2013

The ESO/MPG WFI and the INT WFC wide field archives comprising 330 000 images were mined to search for serendip-itous encounters of known Near Earth Asteroids (NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 as-teroids (44 PHAs and 108 other NEAs) were identified using the PRECOVERY software, their astrometry being measured on 761 images and sent to the Minor Planet Centre. Both recoveries and precoveries were reported, including prolonged orbital arcs for 18 precovered objects and 10 recoveries. We analyze all new opposition data by comparing the orbits fitted before and after including our contributions. We conclude the paper presenting "Mega-Precovery", a new online service focused on data mining of many instrument archives simultaneously for one or a few given asteroids. A total of 28 instrument archives have been made available for mining using this tool, adding together about 2.5 million images forming the "Mega-Archive" © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Paraschiv A.R.,University of Bucharest | Lacatus D.A.,University of Bucharest | Badescu T.,University of Bucharest | Lupu M.G.,University of Bucharest | And 5 more authors.
Solar Physics | Year: 2010

During the 2007 - 2008 minimum of solar activity, the internally occulted coronagraphs SECCHI-COR1 onboard the STEREO space mission recorded numerous jet-like ejections over a great range of latitudes. We have found more than 10000 white-light jets in the above-mentioned period. Sometimes they can be identified on the disk with bright points observed in ultraviolet images by EUVI. In this study we present a catalog consisting of jets observed by the SECCHI-COR1 instrument and their association with lower coronal activity (bright points, UV jets). Furthermore, their association with bright points in the context of previously proposed models is discussed. From the complete catalog we have selected 106 jets observed in both STEREO-A and STEREO-B images for which it is possible to derive their kinematics and point of origin. © 2010 Springer Science+Business Media B.V.

Szakacs A.,Sapientia University | Szakacs A.,Institute Of Geodynamics Sabba S Stefanescu | Pecskay Z.,Hungarian Academy of Sciences | Silye L.,Babes - Bolyai University | And 3 more authors.
Geologica Carpathica | Year: 2012

The Dej Tuff is an important stratigraphic marker in the Transylvanian Basin. However, its Early Badenian age is known only on biostratigraphical grounds so far. A number of radiometric dating techniques including K-Ar, Ar-Ar and fission-track have been used in order to constrain more precisely its age, allowing the calibration of the Transylvanian Basin's evolutionary models. Although individual dating methods could not provide a unique, reliable and accurate radiometric age, comparison and evaluation of multiple methods gives 14.8-15.1 Ma as the most likely formation age of the Dej Tuff.

Barbu M.,University of Bucharest | Faur L.,University of Bucharest | Visan M.,Institute Of Geodynamics Sabba S Stefanescu
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

The Carpathian-Pannonian region (situated in The Eastern and Central Europe) has a great importance in solving the problem regarding the connection of magmatism with the tectonic processes of the area. The region contains Neogene to Quaternary magmatic rocks of highly diverse composition - large volumes of calc-alkaline magmatic products and sporadic small volumes of alkaline magma. The samples were obtained using a portable drill and oriented using both a magnetic and solar compass. In laboratory we identified both the magnetic mineralogy based on field and temperature variation of the magnetic susceptibility and the structure of the natural remanent magnetization using both alternating field demagnetization and thermal demagnetization. Geographical distribution of magnetic polarity in the sampling area corroborated with the available K-Ar ages has allowed us to show that the main phase of eruption in the southern part of the Gurghiu Mountains took place during chron C3An, between 6.7 - 6.0 Ma.

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